Thalassemia: Clinical Guidelines

List of Abbreviations

LIC – Liver Iron Concentration

MCH – mean corpuscular hemoglobin

MCV – Mean Corpuscular Volume

ALT – alanine aminotransferase

AST – aspartate aminotransferase

BCB – Brilliant Cresyl Blue Stain

HIV – human immunodeficiency virus

HPLC – high-performance liquid chromatography

GGT – Gamma-Glutamyl Transferase

HSC – Hematopoietic Stem Cells

DNA – deoxyribonucleic acid

MRI – magnetic resonance imaging

MSE – medical and social expertise

UIBC – unsaturated iron-binding capacity

HPFH – Hereditary Persistence of Fetal Hemoglobin

TS – transferrin saturation

CBC – complete blood count (differential)

UA – urinalysis

TIBC – Total Iron-Binding Capacity

PCR – polymerase chain reaction

GVHD – graft-versus-host disease

HSCT – hematopoietic stem cell transplantation

TDT – Transfusion-Dependent Thalassemia

NTDT – Non-Transfusion-Dependent Thalassemia

TSH – thyroid-stimulating hormone

LFT – Liver Function Test

FSH – follicle-stimulating hormone

CMV — cytomegalovirus

ECG – electrocardiogram

EMH – Extramedullary Hematopoiesis

WLRBC – Leukocyte- and Platelet-Depleted Red Blood Cell Mass

Terms and Definitions

Agranulocytosis – neutrophil count less than 0.5×10⁹/L

Anemia – decrease in hemoglobin concentration

Autosomal recessive inheritance – a pattern of inheritance in which a genetically determined disease manifests if and only if the "defective" gene is inherited from both parents and is not located on sex chromosomes (X and Y)

Alpha-globin – one of the two proteins required for hemoglobin formation

Beta-globin – one of the two proteins required for adult hemoglobin formation

Biopsy – removal of a small tissue sample for diagnostic purposes

Vaccine prophylaxis – administration of vaccines to prevent infections

Donor erythrocytes – erythrocyte-containing components of donor blood (packed red blood cells, red blood cell suspension, washed erythrocytes, WLRBC)

Neutropenia – decreased number of neutrophils in peripheral blood

Normochromic anemia – anemia with normal erythrocyte MCH

X-ray densitometry – measurement of bone mineral density

Reticulocytopenia – decreased number of reticulocytes in peripheral blood

Thrombocytosis – increased number of platelets in peripheral blood

Thrombocytopenia – decreased number of platelets in peripheral blood

Chelator is a substance that forms a stable, nontoxic compound with a metal (in this case, iron) capable of being eliminated from the body

Chelation therapy is the therapeutic use of chelators

Erythroblastopenia – a decrease in the number of erythroblasts in the bone marrow

1. Brief information on the disease or condition

1.1 Definition of the disease or condition

Thalassemias represent a heterogeneous group of hemoglobin disorders characterized by partially or completely suppressed synthesis of normal hemoglobin due to impaired synthesis of one or more globin chains. Several types of thalassemia have been described, named after the affected globin chain. The most common and clinically significant are α-, δβ-, and β-thalassemias [1–3].

1.2 Etiology and pathogenesis of the disease or condition (group of diseases or conditions)

A normal hemoglobin (Hb) molecule consists of a pair of symmetric dimers formed by the association of one α-globin chain with one non-α-globin chain. All human Hbs contain two α or α-like (ζ) chains and two non-α (ε, ^Gγ, ^Aγ, δ, or β) chains. The structure of hemoglobin ensures its rapid saturation with oxygen in the pulmonary alveoli and controlled oxygen transport to tissues. The synthesis of globin chains is switched on sequentially during ontogenesis with the formation of normal hemoglobin:

a) "embryonic" hemoglobin, which is detected from 3 to 10 weeks of fetal maturation and consists of ζ2ε2, α2ε2, and ζ2γ2 tetramers;

б) "fetal" hemoglobin (HbF α2γ2), which is the primary oxygen carrier in the fetus;

в) "adult" hemoglobin (HbA α2β2), which replaces HbF immediately after birth;

г) minor component of "adult" hemoglobin – HbA2 (α2δ2).

Under normal conditions, adult erythrocytes contain approximately 98% HbA, 2% HbA2, and trace amounts of HbF.

The synthesis of various globin chains is regulated by two gene clusters: the α-globin cluster is located on the tip of the short arm of chromosome 16; the β-globin cluster on the short arm of chromosome 11.

During the first five weeks of intrauterine development, hematopoiesis is carried out by primitive erythroblasts of the yolk sac. At the sixth week of gestation, erythropoiesis shifts to the liver. At the same time, the synthesis of ζ-globin chains decreases, while the synthesis of α-globin chains is activated and persists throughout subsequent intrauterine and postnatal development. In the postnatal period, globin chain synthesis occurs in bone marrow erythroblasts.

When the balance of globin chain synthesis is disrupted due to reduced production of α- or β-globin or increased synthesis of α-globin, thalassemia (α-thalassemia or β-thalassemia) develops [1–4].

Currently, depending on the severity of the clinical course and the need for transfusion therapy, these thalassemia syndromes can be divided based on phenotype into two main groups: 1. Transfusion-Dependent Thalassemias (TDT), 2. Non-Transfusion-Dependent Thalassemias (NTDT).

1.3 Epidemiology of the Disease or Condition

Data on the global epidemiology of thalassemia, especially NTDT, are scarce [5]. Globally, about 68,000 children are born with various thalassemia syndromes every year [6–8]. β-Thalassemia is widespread, with 80 to 90 million carriers worldwide (1.5% of the global population). Approximately half of these carriers originate from Southeast Asia [9]. About 23,000 children are born with transfusion-dependent β-thalassemia, with a smaller number having the NTDT form of β-thalassemia [3,6,8]. In the Russian Federation, according to the registry of the National Medical Research Center for Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev of the Russian Ministry of Health, as of January 2024, there are 163 patients under 21 years of age registered with the major form, 66 patients with the intermedia form of β-thalassemia, 496 individuals with the minor form of β-thalassemia, and 56 individuals with various forms of α-thalassemia [10].

1.4 Features of Coding the Disease or Condition

D56.0 – Alpha thalassemia

D56.1 – Beta thalassemia

D56.2 – Delta-beta thalassemia

D56.3 – Thalassemia trait

D56.4 – Hereditary persistence of fetal hemoglobin (HPFH)

D56.8 – Other thalassemias

D56.9 – Thalassemia, unspecified

1.5 Classification of the disease or condition

1. α-Thalassemia – a hemolytic anemia caused by a deficiency in α-globin synthesis resulting from the loss or damage of one or more α-globin genes. Decreased synthesis of α-chains leads to the accumulation of free γ- and β-globin chains and the formation of tetramers from them – γ₄ (Hb Bart’s) and unstable β₄ (Hb H), followed by accelerated erythrocyte destruction. These tetramers have a very high affinity for oxygen and cannot perform oxygen transport function. The clinical presentation of severe α-thalassemia is the consequence of a combination of hypochromic anemia, hemolysis, and defective oxygen transport due to varying amounts of physiologically ineffective Hb in erythrocytes. As a result, the degree of tissue hypoxia is significantly greater than would be expected from the existing degree of anemia.

Clinically, $\alpha$-thalassemia is divided into four groups: silent carrier state, $\alpha$-thalassemia minor, hemoglobin H (HbH) disease, and $\alpha$-thalassemia with fetal hydrops. The severity of the phenotypic manifestations of $\alpha$-thalassemia is directly proportional to the reduction in $\alpha$-globin synthesis.

• Silent carrier state – loss of a single $\alpha$-globin gene (-$\alpha$/$\alpha\alpha$). Phenotypically, silent $\alpha$-thalassemia carriers are difficult to distinguish from healthy individuals. MCV is typically in the range of 78–80 fL, while MCH may be at the lower limit of normal. All other hematological parameters correspond to reference values. Some silent carriers may even have normal MCV values within the range of 80–85 fL. In the neonatal period, some of them have small amounts of Hb Bart’s in the blood (less than 2%), which disappears within the first months of life.

• $\alpha$-Thalassemia minor is a condition that develops upon the loss of two $\alpha$-globin genes (-$\alpha$/-$\alpha$, --/$\alpha\alpha$, -$\alpha$/$\alpha$^T$\alpha$, and $\alpha$^T$\alpha$/$\alpha$^T$\alpha$). These patients generally have no clinical manifestations. Laboratory blood tests reveal microcytosis with an MCV in the range of 70–75 fL, hypochromia with an MCH in the range of 18–22 pg, an increased red blood cell count, an imbalance in the $\alpha$/$\beta$ biosynthetic ratio (around 0.6), and a relative Hb ₂ level at the lower limit of normal. Some individuals, particularly children, may have mild anemia, which, in the presence of mild microcytosis with hypochromia, often leads to a misdiagnosis of iron deficiency anemia. All newborns with this condition have 5–10% Hb Bart’s in their blood, which disappears within the first months of life.

• Hemoglobin H disease is a moderately severe hemolytic condition accompanied by increased fatigue, general discomfort, and splenomegaly. It results from the loss of three out of the four $\alpha$-globin genes (--/-$\alpha$, --/$\alpha$^T$\alpha$, or $\alpha$^T$\alpha$/ $\alpha$^T$\alpha$). The severity of this condition can vary significantly. Most patients (genotype --/-$\alpha$ or --/$\alpha$^T$\alpha$) are non-transfusion-dependent and require red blood cell transfusions primarily during intercurrent illnesses, surgical procedures, or pregnancy. The rest, with the $\alpha$^T$\alpha$/ $\alpha$^T$\alpha$ genotype, are transfusion-dependent from birth. Hematological findings include mild to moderately severe anemia with microcytosis and hypochromia. Red blood cell morphology is significantly altered, showing basophilic stippling, target cells, and teardrop cells (dacrocytes). Brilliant cresyl blue staining reveals Hb H precipitates as multiple punctate inclusions that transform into large aggregates after splenectomy. In vitro chain biosynthesis demonstrates a significant reduction in the $\alpha$/$\beta$ ratio (~0.3).

• $\alpha$-Thalassemia with fetal hydrops develops upon the loss of all four $\alpha$-globin genes (--/--), is incompatible with life, and leads to stillbirth with hydrops fetalis. The predominant hemoglobin in these fetuses is Hb Bart's ($\gamma$₄). Residual synthesis of the embryonic $\zeta$-globin chain ensures the formation of trace amounts of the Hb tetramer (Hb Portland) in the fetus during the second half of pregnancy. More than 50% of newborns are stillborn at various gestational ages, and the remainder die within the first hours of life.

2. $\beta$-Thalassemia

Three clinical syndromes are associated with differences in severity and are historically termed $\beta$-thalassemia major, $\beta$-thalassemia minor, and $\beta$-thalassemia intermedia. The severity of the clinical picture of $\beta$-thalassemia is directly proportional to the degree of globin chain imbalance and depends mainly on the residual production of $\beta$-globin chains. Two other factors can exert a positive influence on chain imbalance: increased production of $\gamma$-globin chains and decreased synthesis of $\alpha$-globin chains due to the co-inheritance of $\alpha$-thalassemia.

• $\beta$-Thalassemia major: typical clinical and hematological features of the disease appear at 3–6 months of age, following the switch to adult globin synthesis, and manifest as severe hypochromic, microcytic hemolytic anemia requiring regular blood transfusions to maintain adequate hemoglobin levels. In children not receiving red blood cell replacement therapy, severe anemia leads to early mortality at 3–4 years of age ($\beta$⁰-thal) or 8–12 years of age ($\beta$⁺-thal). Clinical manifestations also include progressive enlargement of the liver and spleen, typical changes in flat bones due to bone marrow expansion, and pathological fractures of tubular bones. Secondary hypersplenism, leading to thrombocytopenia, leukopenia, and accelerated destruction of transfused red blood cells, further complicates the clinical picture. Growth and pubertal retardation become noticeable by age 10. The course of the disease in inadequately treated patients is complicated by iron overload resulting from transfusions and increased intestinal iron absorption. Hematologically, $\beta$-thalassemia major, in addition to profound anemia, features typical red blood cell morphological changes such as hypochromia, microcytosis, anisopoikilocytosis, polychromasia, fragmentation, basophilic stippling, and numerous normoblasts in the peripheral blood. The reticulocyte count is usually low due to massive destruction of erythroid precursors in the bone marrow. The bone marrow is hypercellular, with marked erythroid hyperplasia and poorly hemoglobinized normoblasts.

  Without replacement therapy, the mean hemoglobin concentration is 50–60 g/L in $\beta$⁰-thalassemia homozygotes and slightly higher—around 70 g/L—in $\beta$⁺-thalassemia homozygotes. The relative content of Hb A₂ varies within wide ranges, and Hb F is always elevated, accounting for up to 98% of total hemoglobin.

• Minor form of b‑thalassemia. Heterozygotes for b⁺‑thalassemia are generally asymptomatic, with Hb at the lower limit of normal, while heterozygotes for b⁰‑thalassemia have grade 1 anemia. Erythrocyte indices MCV and MCH are reduced to typical values of 60–70 fL (normal 85–92 fL) and 20–25 pg (normal 27–32 pg), respectively. Hematological characteristics also include microcytosis, hypochromia, anisopoikilocytosis with target cells and basophilic stippling of peripheral blood erythrocytes, and mild erythroid hyperplasia in the bone marrow. Splenomegaly is rare and usually very slight. The diagnostic test is the quantitative assessment of hemoglobin type ratios (hemoglobin fractions): Hb A₂, which is typically 2 times higher than normal (normal 2–3.5%), and Hb F is slightly elevated in half of cases up to £5%. In vitro biosynthesis of globin chains reveals a deficiency of b chains, with an a/b ratio of 1.5–2.0 (normal 0.9–1.1). Extremely rarely, b⁺⁺‑thalassemia heterozygotes may have normal values of Hb F, Hb A₂, MCV, and MCH.

• $\beta$-Thalassemia intermedia encompasses the entire spectrum of clinical syndromes with a severity intermediate between $\beta$-thalassemia major and minor. Patients with $\beta$-thalassemia intermedia are usually able to maintain hemoglobin levels in the range of 65–90 g/L, exhibit hepatosplenomegaly and typical "thalassemic" skeletal deformities of the flat bones, and may not require regular red blood cell transfusions.

3. Hb Lepore and $\delta\beta$-Thalassemia

Hybrid-chain hemoglobins are classified as quantitative hemoglobinopathies, a prominent representative of which is Hb Lepore. During non-homologous crossing-over, two abnormal chromosomes are formed: the Lepore chromosome with a $\sim$7 kb deletion, which carries a $\delta\beta$ hybrid gene instead of the normal $\delta$ and $\beta$ genes, and the anti-Lepore chromosome, which carries normal $\delta$ and $\beta$ genes along with a fused $\beta\delta$ gene between them. The homozygous state for Hb Lepore can lead to moderate or severe transfusion-dependent thalassemia syndromes.

The characteristics of the main forms of thalassemia according to the genetic defect are presented in Table 1.

Table 1. Clinical and genetic characteristics of thalassemia types

β⁺⁺ – β-globin chain production is slightly decreased; β⁺ – β-globin chain production is significantly decreased; β⁰ – β-globin chain production is completely absent.

1.6 Clinical presentation of the disease or condition

Clinical manifestations of α-thalassemia appear from birth, and in severe cases—Hb Bart's hydrops fetalis—intrauterinely. Patients with minimally altered α-thalassemia have minimal clinical manifestations, such as pallor and increased fatigue, only during intercurrent illnesses.

Hemoglobin H disease clinically presents with minimal signs of hemolysis accompanied by increased fatigue, general malaise, and splenomegaly. At the same time, the degree of tissue hypoxia does not correspond to the degree of hemoglobin reduction, since part of the hemoglobin (namely Hb H) in these patients does not participate in gas transport. The severity of anemia can vary from moderate to severe depending on the α-thalassemia genotype.

Clinical manifestations of β-thalassemia major usually appear at 3–6 months of age, when severe microcytic anemia, mild jaundice, and hepatosplenomegaly develop. Patients with this condition grow poorly, and skin pallor progresses. Such patients may experience feeding difficulties, irritability, recurrent episodes of fever due to a hypermetabolic state or intercurrent infection, and progressive abdominal distension due to enlargement of the spleen and liver. In some regions with limited medical resources, the clinical picture in untreated patients or those receiving insufficient red blood cell transfusions is characterized by growth retardation, pallor, jaundice, poorly developed musculature, genu valgum, hepatosplenomegaly, leg ulcers, tumor-like masses due to EMH, and skeletal changes due to bone marrow expansion. Skeletal changes include long bone deformities of the legs and typical craniofacial bone deformities: thalidomide facies (square skull, prominent cheekbones, flattened nasal bridge, maxillary hypertrophy with protruding upper teeth).

β-thalassemia intermedia can be observed in patients whose clinical signs of the disease appear at a later age, developing the same manifestations but in a milder form. In the most severe cases, symptoms in patients appear between 2 and 6 years of age. Although such patients can survive without regular replacement blood transfusions, they exhibit growth and developmental delay. Erythroid hyperplasia and extramedullary hematopoiesis (EMH) are common. The consequences include characteristic facial bone deformity, osteoporosis and pathological long bone fractures, and the formation of erythropoietic tissue masses primarily affecting the spleen and liver, located paraspinally and near the flat bones of the skull and pelvis. Leg ulcers frequently occur. Patients with β-thalassemia intermedia develop iron overload due to increased intestinal iron absorption.

The clinical picture of Hb Lepore and δβ-thalassemia is similar to that of β-thalassemia intermedia.

The clinical picture of Hb E/β-thalassemia varies from mild, resembling β-thalassemia minor, to severe, resembling β-thalassemia major. To assess the severity of Hb E/β-thalassemia, a special rating scale is used, presented in Appendix G1.

2. Diagnostics, medical indications and contraindications for diagnostic methods

Criteria for establishing the diagnosis/condition:

1. Presence of hypochromia, erythrocyte microcytosis (decreased MCH, MCV)

   Absence of iron deficiency proven by biochemical iron metabolism parameters (serum iron, blood ferritin level study, total iron-binding capacity of serum, blood serum transferrin level study, transferrin iron saturation study—within reference values)

2. Alteration of hemoglobin fractions:

   - β-thalassemia: increased HbF and HbA₂ fractions;

   - α-thalassemia: absence of HbF, decreased HbA₂, possible presence of HbH or HbBart’s

   - δβ-thalassemia and Hb Lepore: increased HbF and HbA₂

   - Hb E/β-thalassemia: increased HbF and HbA₂.

Criteria for dividing thalassemia into transfusion-dependent (TDT) and non-transfusion-dependent (NTDT) forms are presented in Appendix G2.

2.1 Complaints and Anamnesis

Comments: The main complaints are related to the manifestations of anemia: pallor of the skin and mucous membranes, weakness, and fatigue. If the disease is not detected in the neonatal period, a child with severe thalassemia will likely exhibit physical developmental delay, poor appetite, and other nonspecific symptoms of anemia, which may be accompanied by enlargement of the spleen and liver.

• All patients with suspected thalassemia are recommended to undergo a thorough family history taking, including inquiries about family members (children or adults) with a similar disease and the age of onset of the first symptoms, in order to timely establish a diagnosis and assess the patient's condition [3, 12–14]. (CLE 5, LCE C)

• If preliminary screening results are not available, it is recommended to examine the patient's parents to rule out thalassemia trait due to the genetic nature of the disease (quantitative assessment of hemoglobin type ratios (hemoglobin fractions)) [3, 12–14]. (CLE 5, LCE C)

2.2 Physical Examination

• All patients with suspected thalassemia are recommended to undergo a physical examination in order to timely establish a diagnosis and assess the patient's condition [3, 12–14]. (CLE 5, LCE C)

Comments: General examination implies assessing general physical condition, measuring height and weight, head circumference, presence of secondary sexual characteristics appropriate for age, presence of nonspecific signs of anemia, enlargement of the spleen and liver, and any signs of bone mass expansion or facial skeleton appearance changes.

Physical development is poor. Growth retardation occurs almost universally in patients with thalassemia major. Significant growth deceleration is observed in height, sitting height, weight, as well as shoulder and hip width. After 4 years of age, the growth rate noticeably decreases relative to normal values. Bone age is often delayed after 6–7 years of age. Growth retardation becomes severe due to impairment of the pubertal growth spurt. Key factors contributing to growth deceleration in patients with thalassemia include chronic anemia, transfusion iron overload, and chelation toxicity [14].

• When providing care to patients with thalassemia, it is recommended to carefully monitor spleen enlargement symptoms and size during physical examination for the timely detection of splenomegaly and correction of treatment tactics [3, 12–14]. (CLE 5, LCE C)

Comments: Splenomegaly is accompanied by symptoms such as pain in the upper left quadrant of the abdomen or early satiety, and hypersplenism phenomena. Severe splenomegaly leads to the risk of potential splenic rupture.

Leukopenia or thrombocytopenia due to hypersplenism leads to clinical problems (e.g., recurrent bacterial infection or bleeding). Splenomegaly resulting from inadequate replacement transfusion therapy may be reversible.

2.3 Laboratory Diagnostics

To confirm the diagnosis, it is necessary to evaluate clinical manifestations and laboratory test data:

• All patients with suspected thalassemia are recommended to undergo a complete blood count (CBC) with differential (using an automated hematology analyzer) and blood smear review to analyze abnormalities in erythrocyte, platelet, and leukocyte morphology (blood smear microscopy) for differential diagnosis and confirmation of the diagnosis [3, 12–14]. (CLE 5, LCE C)

Comments: Patients with thalassemia typically present with a decreased mean corpuscular hemoglobin (MCH) and a decreased mean corpuscular volume (MCV). Blood smear reveals microcytosis, hypochromia, anisocytosis, poikilocytosis (spiculated teardrop and elongated cells), target cells, and normoblasts. The number of normoblasts (nucleated red blood cells) correlates with the severity of anemia and increases significantly following splenectomy. Overall, these morphological abnormalities and red blood cell characteristics are similar across various forms of thalassemia, including co-inherited abnormal hemoglobins, such as HbE/β-thalassemia [3, 14, 15]. The severity of morphological changes depends on the severity of the thalassemia. Transfusion-dependent thalassemia is characterized by a profound decrease in total blood hemoglobin concentration (<70 g/L), MCV >50 and <70 fL, and MCH >12 and <20 pg. Non-transfusion-dependent thalassemia is characterized by a total blood hemoglobin level above 70 g/L, MCV ranging from 50 to 70 fL, and MCH ranging from 16 to 24 pg.

• All patients with suspected thalassemia are recommended to undergo quantitative assessment of hemoglobin fractions (hemoglobin typing) by electrophoresis (capillary electrophoresis) or high-performance liquid chromatography (HPLC) to establish and differentiate the diagnosis [3, 12–14, 165]. (LEL 5, GOR C)

Comments: The use of capillary electrophoresis increases diagnostic specificity. Although the cost of testing has decreased, it is not yet a universally available practice [2, 3].

• All patients with suspected thalassemia are recommended to undergo molecular genetic testing of globin genes (detection of point mutations in the globin gene combined with molecular genetic testing for globin gene deletions/insertions) to establish the diagnosis and determine the prognosis of the disease [12, 14, 16–21, 165]. (LEL 3, GOR B)

Comments: due to the extremely high frequency of combined globin gene abnormalities, it is advisable to test both a-globin genes and the b-globin gene using various methods to detect both point mutations and deletions/insertions of varying lengths, which will allow for an accurate assessment of the disease prognosis.

2.4 Instrumental Diagnostics

• All patients with thalassemia who have laboratory markers of tissue iron overload are recommended to undergo T2*-weighted magnetic resonance imaging (MRI) of the abdomen (liver) for the timely diagnosis of complications related to blood transfusion therapy [23]. (LEL 1, GOR B)

• All patients with thalassemia who have laboratory markers of tissue iron overload are recommended to undergo cardiac T2*-weighted magnetic resonance imaging (MRI) for the timely diagnosis of complications related to blood transfusion therapy [22]. (LEL 2, GOR C)

• All patients with diagnosed thalassemia are recommended to undergo an ultrasound examination of the liver and spleen for the timely detection of hepatomegaly and splenomegaly, as well as to adjust treatment tactics [14, 24]. (LEL 5, GOR C)

Comments: Patients older than 18 years with a newly diagnosed thalassemia and those with a previously established diagnosis transitioning to adult care require a comprehensive abdominal ultrasound for the timely diagnosis of organomegaly and extramedullary hematopoiesis sites. Splenomegaly is accompanied by symptoms such as upper abdominal pain, early satiety, and hypersplenism. Severe splenomegaly carries the risk of potential splenic rupture.

Leukopenia or thrombocytopenia secondary to hypersplenism leads to clinical issues (e.g., recurrent bacterial infections or bleeding). Splenomegaly resulting from inadequate transfusion therapy may be reversible.

• It is recommended that all adult patients (18 years and older) with newly diagnosed thalassemia and patients with a previously established diagnosis transitioning to the adult cohort undergo MRI or CT imaging for the timely detection of paravertebral sites of extramedullary hematopoiesis requiring reduction to prevent neurological complications caused by nerve trunk and spinal nerve root compression [168, 169] (LEL 4, GOR C).

• It is recommended that all adult thalassemia patients with suspected liver fibrosis/cirrhosis undergo liver elastography, as well as contrast-enhanced abdominal MRI or contrast-enhanced computed tomography of the abdomen for the timely diagnosis of liver cirrhosis, portal hypertension, and exclusion of hepatocellular carcinoma [165, 170] (LEL 5, GOR C).

2.5 Other Procedures

Screening for hemoglobinopathies

• To detect thalassemia carriers within the healthcare system, population screening is recommended [3, 13–15, 25–41]. (LEL 1, GOR B)

Comments: Identification of a carrier parent, usually the mother, followed by partner testing allows for the identification of couples at risk of having an affected child. Based on counseling, they can make an informed choice regarding prenatal diagnosis and pregnancy termination due to fetal abnormalities. The effective delivery of this service has led to a significant reduction in the number of newborns with these disorders in several countries [3, 13–15, 25–41].

In most cases, children with thalassemia major are identified using the same screening test, and early diagnosis can reduce morbidity associated with late complications of thalassemia [27–32].

The approach to thalassemia screening depends on the local frequency of specific mutations, available resources, and cultural and religious characteristics. Public awareness and education, expanded family screening, premarital screening and genetic counseling, prenatal diagnosis, and family planning are among the strategies commonly used in screening programs [14, 15].

• In regions with a high prevalence of thalassemia, universal newborn screening for both α- and β-thalassemia disorders is recommended to initiate early therapy and prevent complications [12–14]. (LEL 5, GOR C)

• All adult patients with thalassemia who have undergone a splenectomy and/or have a history of thrombotic complications are recommended to undergo a coagulation profile (activated partial thromboplastin time, prothrombin time in blood or plasma, plasma fibrinogen level, thromboelastometry) and molecular markers of hereditary thrombophilia (prothrombin G20210A polymorphism in the coagulation factor II gene, G1691A mutation in the coagulation factor V gene (Leiden mutation), methylenetetrahydrofolate reductase C677T polymorphism) for the timely diagnosis and correction of hypercoagulable syndrome to prevent thromboembolic complications [171, 172] (LEL 4, GOR C).

Diagnosis of disease and therapy complications

3. Treatment, including drug and non-drug therapies, diet therapy, and pain management

As with other chronic diseases requiring lifelong and substantial medical interventions, patient well-being is affected not only by technical aspects but also by the methods of care delivery. Patient-centered care is one of the most critical factors, and healthcare organizations should pay special attention to minimizing the negative impact of medical care on patients' education, work, and family life, enabling them to lead as active and normal a lifestyle as possible. Such medical care can significantly improve survival by enhancing adherence to complex treatment regimens [68–71].

3.1 Non-pharmacological therapy

It should be emphasized that the clinical phenotype of thalassemia cannot be accurately predicted at early stages, and the patient must be monitored for clinical signs indicating the need to initiate transfusions, as well as for transfusion-related complications.

• All patients with thalassemia are recommended to follow a healthy lifestyle: a balanced diet, physical activity, and the avoidance of bad habits (smoking, alcohol, use of toxic substances) [3, 12–15, 43, 44, 72, 73]. (LoE 3, GoR B)

Comments: patients with minor β-thalassemia, minimally manifested α-thalassemia, and healthy thalassemia carriers do not require treatment; a healthy lifestyle will allow the body to independently compensate for the genetic defect. Patients with severe clinical forms of thalassemia require not only a healthy lifestyle but also specialized treatment [74–77].

• For all patients with any form of thalassemia at any age, physical activity (recreational exercise, sports without competition) is recommended to maintain skeletal bone mineralization to the maximum extent possible, especially in moderate-to-severe clinical forms of thalassemia [12–14, 72, 78–81]. (LoE 3, GoR B)

3.2 Transfusion and Chelation Therapy

• In patients with non-transfusion-dependent thalassemia (NTDT) forms (intermediate β-thalassemia and other clinically similar forms of thalassemia), transfusion therapy is recommended when hemoglobin drops below 60 g/L, in the presence of concomitant infections, during surgical procedures, during pregnancy, in case of pronounced growth retardation, pulmonary hypertension, heart failure, a tendency toward thrombosis, or the development of severe bone deformities [3, 12–15]. (LoE 5, GoR C)

• In patients with an established (laboratory-confirmed, including molecular-genetic) diagnosis of transfusion-dependent thalassemia (TDT) forms (major β-thalassemia, severe hemoglobinopathy H, and severe E/β-thalassemia), it is recommended to initiate replacement therapy with leukodepleted (leukoreduced) packed red blood cells with individual donor matching [3, 12–15, 165]:

  - Hb less than 70 g/L in 2 measurements, with an interval between measurements of more than 2 weeks (excluding all other predisposing factors such as infections);

  - Hb >70 g/L, but marked by: significant symptoms of anemia, facial bone changes, growth retardation, pathological fractures, extramedullary hematopoiesis (LoE 5, GoR C).

Comments: the decision to initiate regular transfusions is made by the attending physician at a federal-level medical organization specializing in the care of patients with thalassemia, or following a consultation with them (for a list of such medical organizations, see Section 6. Organization of Medical Care). The goal of regular donor red blood cell transfusions is to ensure normal growth and development of the patient, effective suppression of intra- and extramedullary erythropoiesis, and good working capacity [165].

• Patients with TDT forms of thalassemia are strongly recommended to receive lifelong regular transfusions of leukodepleted packed red blood cells with individual donor matching, usually performed every two to five weeks, to maintain pre-transfusion blood hemoglobin above 90–105 g/L. Such a transfusion regimen promotes normal growth, ensures normal physical activity, adequately suppresses excessive bone marrow activity in most patients, and minimizes iron accumulation [12–14, 24, 165]. (LoE 5, GoR C)

Comments: a higher pre-transfusion blood hemoglobin level of 110–120 g/L may be advisable for patients with cardiovascular disease or other pathological conditions, as well as for those in whom adequate suppression of excessive bone marrow activity has not been achieved. Although shorter intervals between transfusions may reduce patients' overall transfusion requirements, other factors such as work schedules, school timetables, and other aspects of the patients' lifestyle must be taken into account when choosing intervals.

• For programmed replacement therapy, it is recommended to use individually matched, leukodepleted, and irradiated packed red blood cells to reduce the risk of various post-transfusion reactions (complications) (fever, CMV infection, alloimmunization) [12–15, 82–88, 165]. (LoE 5, GoR C)

• It is recommended to use a normotransfusion regimen for programmed replacement therapy with packed red blood cells, i.e., the post-transfusion Hb level should not exceed 130 g/L. The volume of transfused packed red blood cells is 20–30 mL/kg, with a frequency of every 2–5 weeks [12–15, 165]. (LoE 5, GoR C)

• Before the first red blood cell transfusion, it is recommended to perform the following tests to minimize the risks of alloimmune complications, detect hepatitis B and C and HIV infection, and assess the degree of iron overload due to increased intestinal iron absorption in prolonged severe anemia [12–14, 91–93, 165]:

  - determination of major ABO blood groups, Rhesus D antigen (Rh factor), and determination of subgroups and other minor blood groups A-1, A-2, D, Cc, E, Kell, Kidd, Duffy (complete extended red blood cell phenotype and genotype [C, c, D, E, e, K, k, Jka, Jkb, Fya, Fyb, Kpa, Kpb, MNS, Lewis]);

  - general (clinical) blood test and serum ferritin level testing;

  - tests for hepatitis B, C, and HIV: determination of antibodies to hepatitis B surface antigen (HBsAg) in blood; determination of antibodies to hepatitis C virus in blood; determination of IgM and IgG antibodies to human immunodeficiency virus HIV-1 in blood; determination of IgM and IgG antibodies to human immunodeficiency virus HIV-2 in blood. (LoE 5, GoR C)

Comments: it is assumed that β-globin and α-globin genotyping has already been performed during diagnosis. If not, it should be performed, whenever possible, before the first transfusion.

• During replacement transfusion therapy, to evaluate the efficacy and safety of therapy and ensure its timely adjustment, it is recommended to monitor the patient's condition by performing the following tests [12–14, 91–95, 164-166]:

  - complete (clinical) blood count with platelet and normoblast counts before each transfusion;

  - direct antiglobulin test (direct Coombs test) and indirect antiglobulin test (indirect Coombs test) before each transfusion, with determination of red blood cell antibody specificity (if detected);

  - determination of major ABO blood groups, Rhesus D antigen (Rh factor), and determination of subgroups and other minor blood groups A-1, A-2, D, Cc, E, Kell, Duffy, Kidd – once a year;

  - serum iron testing, total iron-binding capacity (TIBC/UIBC) testing, transferrin saturation testing, and serum ferritin level testing – once every 6–12 months. (LoE 5, GoR C).

3.3 Pharmacotherapy

Comments: Red blood cell transfusion therapy must be accompanied by adequate chelation therapy to prevent severe organ damage [1, 3, 98–102]. It is recommended to discontinue chelation therapy only when the upper limit of the age-adjusted normal serum ferritin level is reached, provided that replacement transfusion therapy is discontinued and iron content in the liver and myocardium, assessed by T2* MRI, has normalized (for the liver, the atomic absorption method for determining iron content in the dry weight of a liver biopsy specimen is also acceptable) [3, 12–14, 72].

• For the prevention and treatment of chronic post-transfusional iron overload in adults and children aged 2 years and older, the following chelation therapy options are recommended [164-166]:

  - Deferasirox**:

  • initial dose for the dispersible tablet formulation is 20 mg/kg/day orally daily, then increased in steps of 5 mg/kg/day up to a maximum dose of 40 mg/kg/day or decreased depending on serum ferritin concentration; if the serum ferritin level is less than 500 mcg/L, the dose is reduced to 125-250 mg/mg/day;

  • initial dose for the film-coated tablet formulation is 14 mg/kg/day orally daily, then increased or decreased in steps of 3.5 mg/kg/day depending on serum ferritin; maximum dose is 28 mg/kg/day; if the serum ferritin level is less than 500 mcg/L, the dose is reduced to 90-180 mg/day [103–106]. (LEL 1, GOR A)

• During chelation therapy, to assess treatment efficacy and safety and for timely dose adjustment, patient monitoring with the following tests is recommended [1, 3, 12–15, 97, 164-166]:

  - determination of serum iron, total iron-binding capacity (TIBC/UIBC), transferrin saturation, and blood ferritin level – every 3 months during titration of the chelating agent (V03AC Iron-chelating agents), then every 6–12 months;

  - assessment of proteinuria (urine protein determination) – before starting therapy, weekly during the dose titration or escalation phase;

  - assessment of nephron function via creatinine clearance (Rehberg's test) – before starting chelation therapy, every 3 months during the dose titration phase, then every 6–12 months; deferasirox** is contraindicated in patients with GFR <40 mL/min.

  - general clinical biochemical blood test with assessment of liver and kidney function – before starting chelation therapy, every 2 weeks during the dose titration or escalation phase, then every 1–3 months;

  - T2* MRI of the liver and myocardium – once a year;

  - Pure-tone audiometry before starting therapy and once every 12 months.

  (LEL 5, GOR C);

• Patients with transfusion-dependent thalassemia in the presence of paraspinal extramedullary hematopoiesis foci are recommended cytoreductive therapy with #hydroxycarbamide** at a dose of 7.5 to 20 mg/kg/day [165]. (LEL 5, GOR C)

Comment: the effect of #hydroxycarbamide** is mediated by stimulating fetal hemoglobin synthesis and reducing the imbalance between alpha and non-alpha globin chains, which leads to increased efficacy and decreased intensity of erythropoiesis. The additional cytoreductive effect of #hydroxycarbamide** leads to a reduction in the volume of extramedullary hematopoietic foci.

• For the treatment of adult patients with transfusion-dependent thalassemia when it is impossible to maintain the transfusion regimen required to achieve target hemoglobin concentrations (due to alloimmunization from multiple blood transfusions, Coombs-positive hemolytic anemia, including in splenectomized patients), luspatercept therapy is recommended at an initial dose of 1 mg/kg every 3 weeks; if no response is observed within 6 weeks, increase the dose to 1.25 mg/kg (do not increase the dose above the maximum dose of 1.25 mg/kg once every 3 weeks) [107–110, 164-166]. (LEL 2, GOR B)

Comment: The efficacy and safety of luspatercept in adult patients with transfusion-dependent beta-thalassemia were studied in the randomized, double-blind Phase 3 BELIEVE trial [109]. The efficacy and safety of luspatercept in adult patients with non-transfusion-dependent beta-thalassemia were studied in the randomized, double-blind Phase 2 BEYOND trial [110].

Given the limited practical experience with luspatercept in Russia, initiation of therapy and dose adjustment should be performed exclusively in one of the federal centers.

Initial results of studies on the efficacy and safety of luspatercept in children aged 12 years and older have demonstrated an efficacy and safety profile similar to that of adult patients [111].

3.4 Splenectomy

Comments: patients with intermediate and major forms of b-thalassemia may require a splenectomy. However, adequately managed treatment after diagnosis can prevent the development of hypersplenism and, accordingly, reduce the need for splenectomy [114, 164].

For patients receiving effective chelation therapy, despite an increased need for transfusion therapy, splenectomy may not be mandatory. Although the total body iron burden decreases after splenectomy, iron is redistributed and accumulates in the liver, heart, and other organs, and unless effective chelation protocols are implemented, the iron concentration in these organs will increase and may lead to life-threatening organ dysfunction [115, 116].

Before deciding on a splenectomy in such a situation, the patient should be switched to an adequate blood transfusion program for several months, followed by a re-evaluation of their condition.

• Splenectomy is not recommended in children under 5 years of age due to the increased risk of sepsis [12–14, 117]. (LEL 5, GOR C)

• Vaccine prophylaxis. Before splenectomy, all pediatric patients are recommended to receive full vaccination in accordance with the National Immunization Schedule, as well as against pneumococcal, meningococcal, and Haemophilus influenzae type b infections [164-166]. (LEL 5, GOR C)

3.5 Hematopoietic Stem Cell Transplantation

• Hematopoietic stem cell transplantation (HSCT, hematopoietic cell transfusion) is recommended for patients at an early age or prior to the development of iron overload-related complications. However, the final decision should be based on an assessment of the relative benefits and risks of HSCT versus conventional therapy, requiring physicians, patients, and their families to weigh the outcomes and potential risks of each treatment modality [13, 14, 118, 164-166]. (LEL 3, GOR B)

Comments: The source of hematopoietic stem cells can be either bone marrow or peripheral blood. HSCT from HLA-identical siblings is increasingly used in the treatment of hemoglobinopathies. Since 1981, extensive clinical experience has been gained from more than 1,500 HSCT procedures performed at various centers worldwide. Over this period, a number of factors—the use of cyclosporine**, the introduction of desensitization protocols, the improvement of conditioning regimens (treosulfan**) and complication prophylaxis, more effective treatment of cytomegalovirus infection, improved aseptic techniques, and the development of systemic antibiotic therapy—have led to outstanding achievements in HSCT outcomes [118–122].

Three classes of patients were identified based on the risk factors described below, which were found to have a significant impact on transplantation outcomes:

- inadequate chelation therapy;

- presence of liver fibrosis;

- hepatomegaly [123].

Class I patients do not have the above characteristics, Class II patients have one or two characteristics, and Class III patients have all three characteristics.

Among pediatric patients with thalassemia classified as Class I who underwent HSCT in the early stages of the disease, the probability of overall and event-free survival is 93% and 91%, respectively, with a 2% risk of rejection and an 8% risk of transplantation-related mortality.

Class II patients have an 87% probability of overall survival and an 83% chance of event-free survival, with a 3% risk of rejection and a 15% risk of non-rejection-related mortality, whereas Class III patients have a 79% probability of overall survival and a 58% chance of event-free survival, with a 28% risk of rejection and a 19% risk of non-rejection-related mortality (Centers performing transplantation in patients with similar characteristics report comparable results [124]).

In the case of Class III patients, administering a regimen containing less than 200 mg/kg of cyclophosphamide** significantly reduces transplantation-related mortality, but at the same time increases the risk of graft rejection.

Among adult patients (over 16 years of age), the probability of overall survival after HSCT is 66%, with a 62% probability of cure, a 35% chance of HSCT-related death, and a 5% probability of returning to the pre-transplant thalassemic state.

HLA-matched sibling donors

The overall applicability of HSCT is limited by the availability of a related HLA-matched donor. There is a 1 in 4 chance that any given sibling will be HLA-identical, and the probability that a patient with thalassemia will have an HLA-identical sibling donor varies depending on family size.

Transplantation from matched unrelated donors

Unfortunately, the number of complications accompanying HSCT using matched unrelated donors is generally higher than with related matched donors. The use of modern HSCT protocols can reduce the number of complications to an acceptable level, provided the patient received adequate therapy prior to the decision to undergo transplantation (i.e., the patient belongs to Class I).

Mixed chimerism

The persistence of residual host hematopoietic cells, commonly referred to as mixed chimerism, is frequently observed after HSCT for $\beta$-thalassemia [124]. Reducing the dose of busulfan** or cyclophosphamide** in conditioning regimens leads to high levels of mixed chimerism, which is a risk factor for graft rejection. None of the patients with full donor chimerism experienced graft rejection, whereas 29% of patients with mixed chimerism rejected the graft within two years post-HSCT. Despite this, long-term (more than 2 years) stable mixed chimerism has been observed following successful HSCT for thalassemia.

Preparation for HSCT: desensitization therapy, maximally effective chelation therapy to reduce HSCT toxicity.

3.5 Cord Blood Hematopoietic Stem Cell Transplantation

• Umbilical cord blood hematopoietic stem cell transplantation is recommended only for young patients with low body weight due to the limited number of CD34+ cells in harvested cord blood [13, 125–128]. (LoE 4, GoR C)

Comments: recently, significant attention has been paid to the use of stem cells derived from umbilical cord blood at birth. There are several potential advantages to this source of hematopoietic stem cells (HSCs). First, HSCs can be easily obtained at birth, often in sufficient volume for transplantation—avoiding the need for donor HSC harvesting at a later age. Second, it has been suggested that graft-versus-host disease (GvHD) may be less severe when HSCs are derived from umbilical cord blood. Third, regular collection of cord blood cells during all births will provide a broader donor pool for HSCT. In many cases, the number of harvested hematopoietic stem cells is insufficient for engraftment in an adult recipient.

3.6 Pain Management

• Patients with thalassemia are recommended non-pharmacological prevention of bone pain syndrome through an active lifestyle and, if necessary, pharmacological therapy [73]. (LoE 4, GoR C)

3.7. Diet therapy

Diet therapy is not provided.

4. Medical Rehabilitation and Sanatorium-Resort Treatment

4.1 Psychosocial Rehabilitation in Thalassemia

As a chronic, lifelong, and life-limiting disease, thalassemia is accompanied by numerous and severe challenges [129]. Along with the somatic symptoms of thalassemia and its impact on family, relationships, emotional well-being, and quality of life, a child or adult with thalassemia must cope with invasive, complex, and costly procedures, frequent visits to medical organizations, and lifelong dependence on physicians.

• It is recommended that all patients with thalassemia be provided with access to specialized psychological support services; if psychological difficulties are suspected, an initial appointment (testing, consultation) with a medical psychologist should be conducted (only after discussing and agreeing upon this matter with the patient) [13, 69, 72, 130–132, 164–166]. (LoE 2, GoR B)

• To improve psychological well-being and treatment adherence, group psychotherapy—participation in specialized support groups—is recommended for all patients with thalassemia [12–14]. (LoE 5, GoR C)

• It is recommended to involve patients and their families in the selection and adaptation of treatment regimens whenever possible, in order to improve psychological well-being, treatment adherence, and efficacy [12–14]. (LoE 5, GoR C)

Comments: Changes to treatment should always be preceded by a comprehensive discussion, and the rationale and underlying reasons must be explained in detail. Therapy must take into account the patient's developmental level, family structure, cultural perceptions of illness and treatment, social context, and daily needs. Patients should have access to information about treatment options, including relative advantages or disadvantages and potential consequences of non-adherence to the prescribed treatment regimen (patient information is provided in Appendix B). To vividly demonstrate the importance of treatment adherence to patients, they should be involved in monitoring their own progress, such as ferritin levels and quantitative tissue iron assessment results using imaging methods. In some cases, during the initial stages of adapting to a new treatment regimen, it is advisable to increase the frequency of examinations [129, 133–135].

Comments: following the transition, it is advisable to ensure regular follow-up examinations for adult patients (see 5.2 Dispensary monitoring) to ensure that patients receive optimal medical and psychosocial care [136].

4.2 Medical Rehabilitation

• To improve quality of life, medical rehabilitation is recommended for all patients with thalassemia in accordance with rehabilitation principles for existing disease complications and the scope of treatment received [137–144]. (LoE 5, GoR C)

4.3 Sanatorium-Resort Treatment

• Sanatorium-resort treatment is recommended for all patients with thalassemia to improve their quality of life and promote recovery, in accordance with sanatorium-resort treatment principles for existing disease complications and the scope of treatment received [141, 145, 146]. (LoE 5, GoR C)

5. Prevention and Dispensary Observation

5.1 Prevention of Complications

• Vaccination at least against viral hepatitis B, pneumococcal infection, Haemophilus influenzae type b, meningococcal infection, and influenza in accordance with the National Immunization Schedule is recommended to prevent infectious complications, including long-term ones [14]. (LoE 5, GoR C)

• Continuous monitoring of complications in patients with thalassemia is recommended to improve patient survival [12–14]. (LoE 5, GoR C)

Comments: Constant monitoring of complications and their timely treatment, whenever possible, goes hand in hand with organizing regular transfusions and lifelong iron chelation therapy.

• To reduce the risk of infectious complications, it is recommended to monitor the degree of iron overload and administer adequate chelation therapy [12–14, 147–149]. (Coded as Level of Evidence 5, Grade of Recommendation C)

Comments: hepatic iron overload should be assessed using a non-invasive strategy based on the combined use of blood ferritin levels and liver MRI T2* data [150–153] (see 5.2 Dispensary follow-up).

5.2 Dispensary monitoring

• Starting from 3 months of age and until the clinical phenotype is established, visits to a hematologist or pediatric oncologist-hematologist are recommended at least once a month. Any feeding issues, infections, episodes of poor health, and developmental delays must be monitored. The examination includes assessment of growth, bone mass accumulation (including head circumference measurement), and hepatosplenomegaly. Total blood hemoglobin levels should be checked at least once a month [3, 12–15, 72]. (Coded as Level of Evidence 5, Grade of Recommendation C)

Comments: following diagnosis, patients must undergo regular examinations locally and maintain contact with the specialized Federal Center.

• In order to timely detect and correct complications of the disease and therapy, it is recommended to follow the schedule of specialist consultations and diagnostic procedures within the framework of the patient's dispensary follow-up, as presented in Appendix A3.2 [3, 12–15, 72]. (Coded as Level of Evidence 5, Grade of Recommendation C)

6. Organization of Medical Care

After confirmation of the diagnosis and selection of treatment tactics, the patient is transferred to the local hematologist or pediatric oncologist-hematologist for dispensary follow-up. It is also necessary to consider consulting the patient at one of the Federal Centers providing specialized care for patients with thalassemia.

Therapy is administered long-term/lifelong. Patients and their family members must be thoroughly informed about the nature of the disease, potential complications of the disease itself and the therapy administered, and instructed in personal hygiene rules.

Indications for hospital admission to a medical organization:

1) Scheduled hospitalization in a day or 24-hour inpatient facility for planned red blood cell suspension transfusion.

2) Scheduled hospitalization in a 24-hour inpatient facility for hematopoietic stem cell transplantation after a decision on this procedure has been made.

3) Planned hospitalization in a day hospital for iron overload examination if outpatient examination is impossible (e.g., performing T2* MRI under general anesthesia).

Although most thalassemia therapy is performed on a planned basis, there are conditions that require emergency hospitalization.

Indications for emergency hospitalization in a 24-hour inpatient facility:

1) Heart failure, cardiac arrhythmias

2) Sepsis, including post-splenectomy

3) Venous thromboembolism

4) Osteoporotic fracture

5) Cholelithiasis

6) Decompensation of chronic liver failure – cirrhosis, viral hepatitis

Indications for patient discharge from a medical organization

1) stabilization of the condition;

2) improvement of general well-being;

3) increase in blood hemoglobin concentration up to 115–125 g/L.

7. Additional Information

Cardiac Complications in Thalassemia

In the absence of effective chelation therapy, many patients experience iron-induced myocardial disorders leading to heart failure, arrhythmias, progressive congestive heart failure, or sudden death [150, 154]. The mainstay of cardiac therapy must be aggressive chelation therapy to rapidly counteract iron toxicity and progressively remove excess iron deposits [155].

Iron overload-related cardiac dysfunction typically develops over several years [156]. Unfortunately, cardiac iron clearance is an extremely slow process, often requiring 3 or more years [157]. Thus, preventing myocardial iron accumulation and early recognition of preclinical disease (using T2* MRI) have a much higher chance of success than waiting for ECG changes, clinical signs of cardiac dysfunction, or clinical symptoms [158, 159].

The Liver in Thalassemia

Normally, about 1/3 of the body's iron stores (ferritin and hemosiderin) are located in the liver. About 98% of hepatic iron is found in hepatocytes, which account for up to 80% of the total liver mass; the remaining 1.5–2% of total hepatic iron is found in reticuloendothelial cells, endothelial cells, bile duct cells, and fibroblasts. Progressive accumulation of iron stores is accompanied by cellular toxicity. Iron also has a direct effect on collagen synthesis and/or degradation and changes in microsomal enzymes.

The liver plays a central role in iron homeostasis. In patients with thalassemia in the absence of confounding factors, the threshold liver iron concentration for the development of fibrosis is approximately 16 mg/g dry liver weight [150]. The hepatic iron content is determined both by T2* MRI and histological examination of a biopsy specimen, with the non-invasive method being preferred.

Endocrine disorders

Endocrine disorders are among the most common complications of β-thalassemia. Despite the early initiation of appropriate chelation therapy, problems such as growth retardation, delayed puberty, impaired carbohydrate metabolism, hypothyroidism, hypoparathyroidism, and reproductive dysfunction may persist [160–162]. Patients with thalassemia require regular monitoring by specialists for endocrine complications (see Dispensary follow-up).

Infectious Complications

Infections are the second most common cause of death in transfusion-dependent thalassemia [163]. Specialists involved in the care of thalassemia must be fully aware of this risk and the importance of any intervention that can limit it [160].

National Hemoglobinopathy Registry

In such diseases, systematic record-keeping of all patients is fundamental for planning, referral, service delivery, and monitoring. The National Hemoglobinopathy Registry serves as the official platform for collecting all necessary data. It is continuously updated and improved to maximize its value for healthcare delivery and quality auditing. Every patient with thalassemia must be informed about the National Hemoglobinopathy Registry and asked for consent to include their data, including adverse events and regular examination results. Timely data entry for consenting patients contributes to meeting many management and audit requirements.

Criteria for Evaluating the Quality of Medical Care

References

Appendix A1. Working Group Composition

1. Natalia S. Smetanina – Doctor of Medical Sciences, Professor, Member of the National Hematological Society, Member of the Russian Society of Pediatric Oncologists and Hematologists, Member of the European Hematology Association, Member of the International Bioiron Society; Deputy Director of the Institute of Hematology, Immunology and Cell Technologies, Federal State Budgetary Institution "Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology" of the Ministry of Health of the Russian Federation, Moscow

2. Elena A. Lukina – Doctor of Medical Sciences, Professor, Member of the National Hematological Society, Member of the International Bioiron Society; Head of the Department of Orphan Diseases, Federal State Budgetary Institution "National Medical Research Center for Hematology" of the Ministry of Health of the Russian Federation, Moscow

3. Evgeny A. Nikitin – Doctor of Medical Sciences, Professor, Member of the National Hematological Society; Head of the Department of Hematology and Transfusiology named after Academicians I.A. Kassirsky and A.I. Vorobyov, Federal State Budgetary Institution of Additional Professional Education "Russian Medical Academy of Continuous Professional Education" of the Ministry of Health of the Russian Federation; Head of the Day Hospital, S.P. Botkin Moscow City Multidisciplinary Clinical Research Center of the Moscow City Health Department

4. Lyudmila S. Zubarovskaya – Doctor of Medical Sciences, Professor, Deputy Director for Transplantation at the Clinic of the R.M. Gorbacheva Research Institute of Pediatric Oncology, Hematology and Transplantology, Pavlov First Saint Petersburg State Medical University of the Ministry of Health of Russia, Member of the National Hematological Society, Member of the Russian Society of Pediatric Oncologists and Hematologists

5. Olga A. Slesarchuk – Candidate of Medical Sciences, Head of the Bone Marrow Transplantation Department for Children with Orphan Diseases at the Clinic of the R.M. Gorbacheva Research Institute of Pediatric Oncology, Hematology and Transplantology, Pavlov First Saint Petersburg State Medical University of the Ministry of Health of Russia, Member of the National Hematological Society, Member of the Russian Society of Pediatric Oncologists and Hematologists

6. Karapet S. Aslanyan – Candidate of Medical Sciences, Member of the Russian Society of Pediatric Oncologists and Hematologists, Member of the National Hematological Society; Chief freelance pediatric oncologist-hematologist of the Ministry of Health of the Rostov Region; Director of the Center for Pediatric Oncology and Hematology of the Rostov Region State Budgetary Institution "Regional Children's Clinical Hospital", Rostov-on-Don

7. Dmitry N. Balashov – Doctor of Medical Sciences, Member of the Russian Society of Pediatric Oncologists and Hematologists, Member of the European Hematology Association; Head of the Hematopoietic Stem Cell Transplantation Department No. 2, Federal State Budgetary Institution "Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology" of the Ministry of Health of the Russian Federation, Moscow

8. Marina V. Krasilnikova – Candidate of Medical Sciences, Member of the Russian Society of Pediatric Oncologists and Hematologists; Hematologist at the Advisory Department, Federal State Budgetary Institution "Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology" of the Ministry of Health of the Russian Federation, Moscow

9. Vladimir V. Lebedev – Candidate of Medical Sciences, Member of the Russian Society of Pediatric Oncologists and Hematologists; Chief freelance pediatric oncologist-hematologist of the Southern Federal District of the Russian Ministry of Health; Chief freelance pediatric oncologist-hematologist of the Ministry of Health of Krasnodar Krai; Head of the Department of Oncology and Hematology with Chemotherapy, Children's Regional Clinical Hospital, Krasnodar

10. Nina V. Tsvetaeva – Candidate of Medical Sciences, Member of the National Hematological Society; Senior Researcher at the Department of Orphan Diseases, Federal State Budgetary Institution "National Medical Research Center for Hematology" of the Ministry of Health of the Russian Federation, Moscow

11. Rodion V. Ponomarev – Candidate of Medical Sciences, Member of the National Hematological Society; Hematologist at the Department of Hematology and Chemotherapy of Orphan Diseases, Federal State Budgetary Institution "National Medical Research Center for Hematology" of the Ministry of Health of the Russian Federation, Moscow

12. Svetlana A. Lugovskaya – Doctor of Medical Sciences, Professor, Member of the Russian Association of Medical Laboratory Diagnostics, Professor at the Department of Laboratory Diagnostics, Federal State Budgetary Institution of Additional Professional Education "Russian Medical Academy of Continuous Professional Education" of the Ministry of Health of Russia

13. Pavel E. Trakhtman – Doctor of Medical Sciences, Associate Professor, Head of the Department of Transfusiology, HSC Harvesting and Processing, Dmitry Rogachev NMRCPHOI of the Ministry of Health of Russia, Member of the Russian Society of Pediatric Oncologists and Hematologists, Member of the Russian Association of Transfusiologists

14. Maria A. Lunyakova – Candidate of Medical Sciences, Member of the Russian Society of Pediatric Oncologists and Hematologists; Chief Medical Officer of the Clinic of Hematology, Oncology and Immunology, Ryazan State Medical University named after Academician I.P. Pavlov of the Ministry of Health of Russia, Ryazan

Appendix A2. Methodology for Developing Clinical Guidelines

Target audience for these clinical guidelines:

1. Hematologists

2. Pediatric oncologists-hematologists.

3. Pediatricians

4. Internists

5. General practitioners

Table 1. Scale for assessing levels of evidence (LE) for diagnostic methods (diagnostic interventions)

Table 2. Scale for assessing levels of evidence (LE) for prevention, treatment and rehabilitation methods (preventive, therapeutic, rehabilitation interventions)

Table 3. Scale for assessing grades of recommendation (GR) for prevention, diagnosis, treatment and rehabilitation methods (preventive, diagnostic, therapeutic, rehabilitation interventions)

Procedure for updating clinical guidelines.

The mechanism for updating clinical guidelines provides for their systematic revision at least once every three years, as well as upon the emergence of new evidence-based medicine data on the diagnosis, treatment, prevention, and rehabilitation of specific diseases, or in the presence of justified additions/comments to previously approved clinical guidelines, but no more frequently than once every 6 months.

Appendix A3. Reference Materials

Appendix A3.1 Follow-up Schedule and Monitoring Protocol

Appendix B. Physician Action Algorithms

B1. Diagnostic Algorithm for TDT

B2. Diagnostic Algorithm for NTDT

B3. Iron Overload Assessment and Management Algorithm for NTDT Patients

B4. Management tactics for NTDT (e.g., non-transfusion-dependent β-thalassemia)

Appendix C. Patient Information

What is thalassemia?

The name "thalassemia" comes from the Greek word "sea", "thalassemia", and translates as "sea anemia", as the disease was first discovered in individuals living along the shores of the Mediterranean Sea. Thalassemias are a group of hereditary diseases resulting from an imbalance of alpha or beta chains of a special globulin protein. Globulin forms hemoglobin. Hemoglobin is vital for the body as it is part of red blood cells (erythrocytes), which transport oxygen from the lungs to all tissues and organs. Thalassemia manifests as hemolytic anemia of varying severity. Due to the breakdown of defective hemoglobin, red blood cells are rapidly destroyed. The body tries to compensate for the hemoglobin deficit by increasing the production of red blood cells in the bone marrow. Alpha-thalassemia is the result of insufficient production of alpha-globin chains. Beta-thalassemia is the result of insufficient synthesis of beta-globin chains.

Causes of thalassemia

Thalassemia is a genetic disease caused by damage to hemoglobin genes, and the severity of the disease depends on the extent of the gene defect. 3 In a healthy person, four alpha-globin genes, two on each 16th chromosome (αα/αα), are responsible for the formation of alpha-globin genes. The loss of one alpha-globin gene (-α/αα or αT α/αα) presents as an asymptomatic form of alpha-thalassemia. The loss of two alpha-globin genes (-α/-α or --/αα) is accompanied by a mild course of alpha-thalassemia – alpha-thalassemia trait. The loss of function of three alpha-globin genes (--/-α or --/αT α) manifests as clinically pronounced changes (hemoglobin may range from 30 g/l to 100 g/l). This form is called hemoglobin H disease. The loss of function of all four alpha-globin genes is associated with intrauterine fetal death or premature birth of a child with hydrops fetalis. Currently, intrauterine packed red blood cell transfusions make it possible to save the lives of such patients. Beta-globins are encoded by the beta-globin gene located on the 11th chromosome (β/β). Normal formation of the hemoglobin molecule requires the function of two beta-globin genes (β/β). Gene dysfunction can be minor, i.e., the amount of beta-globin chains produced is slightly below normal (β⁺⁺), significant (the amount of beta-globin chains produced is significantly below normal (β⁺), or total absence of gene function (synthesis of beta-globin chains is impossible (β⁰)). If a person has only one damaged beta-globin gene, the disease – beta-thalassemia – is usually mild (minor form or healthy carrier). Damage to both genes leads to a severe course of beta-thalassemia – intermedia and major forms, the latter known as Cooley's anemia. Combinations of alpha- and beta-thalassemia are possible, which relatively balances the synthesis of alpha- and beta-globin chains, leading to a milder manifestation of the disease; rarely, a combination of beta-thalassemia and an increased number of alpha-globin genes known as alpha-globin gene triplication is possible, which significantly worsens the course of thalassemia.

What to do if diagnosed with thalassemia?

Your attending physician should refer you to a local hematologist, who should then provide a referral to one of the Federal Centers listed below for diagnosis (confirmation of thalassemia) and prescription of appropriate treatment. To receive the necessary treatment, it is also important to obtain disability status; therefore, the medical organization's report should include recommendations for undergoing medical and social examination (MSE) at the place of residence, in addition to therapy information. In accordance with the List of Population Groups and Disease Categories for which outpatient treatment provides free medicinal products and medical devices upon doctor's prescriptions, approved by Decree of the Government of the Russian Federation No. 890 dated July 30, 1994, "On State Support for the Development of the Medical Industry and Improvement of the Supply of Medicines and Medical Devices to the Population and Healthcare Institutions," disabled children under 18 years of age are provided with all medicines free of charge upon doctor's prescriptions. In addition, thalassemia belongs to hematological diseases (hereditary hemopathies), and drugs for the treatment of these diseases and correction of complications from their treatment must also be provided to patients free of charge upon doctor's prescriptions.

What is standard thalassemia therapy?

Patients with beta-thalassemia minor and healthy carriers of thalassemia do not require treatment. For them, maintaining a healthy lifestyle is very important: a balanced diet, physical activity, and avoidance of bad habits (smoking, alcohol, use of toxic substances), which will allow the body to independently compensate for the genetic defect. Patients with severe clinical forms of thalassemia need not only a healthy lifestyle, but also special treatment. Physical activity—recreational exercise and sports (without participating in competitions)—is fundamentally important for all patients with any form of thalassemia at any age, as it maximizes the preservation of skeletal bone mineralization, especially in moderate and severe clinical forms of thalassemia.

Transfusion therapy (packed red blood cells or suspension transfusions)

Patients with moderately severe forms of thalassemia (beta-thalassemia intermedia and other clinically similar forms of thalassemia) rarely require donor red blood cell transfusions (e.g., when hemoglobin drops below 50 g/l, during concurrent infections, during surgical procedures, during pregnancy, with marked growth retardation, pulmonary hypertension, heart failure, tendency to thrombosis, severe bone deformities). Patients with severe forms of thalassemia (beta-thalassemia major and other clinically similar forms of thalassemia) are forced to receive regular donor red blood cell transfusions every 3–4 weeks throughout their lives to maintain normal growth and development rates in childhood, and to maintain a quality and duration of life no different from healthy people in adulthood. When prescribing donor red blood cell transfusions, the doctor will explain in detail what standard thalassemia therapy is, how the transfusion will take place, why it needs to be performed, will perform a compatibility test of donor red blood cells with your blood, and will explain what transfusion reactions may occur and what you should do in such cases. You should listen carefully to the doctor, and if you have any questions, do not hesitate to ask them before the transfusion begins, and then carefully follow the doctor's advice.

Chelation therapy

This is treatment aimed at removing excess iron from the patient's body. Medicinal products approved for medical use in the territory of the Russian Federation (deferasirox**) are used in accordance with the instructions.

What tests are necessary to monitor treatment?

Complete (clinical) blood count (detailed), which allows the physician to assess how adequately treatment for a clinically significant form of thalassemia is organized. General therapeutic blood chemistry analysis allows assessing the safety of the therapy administered to you (your child). Ultrasound examination of the liver and spleen is necessary to assess the degree of hepatosplenomegaly. Cardiac function assessment (electrocardiography, echocardiography, and Holter ECG monitoring if necessary) for all patients with clinically significant forms of thalassemia from the time of diagnosis and annually thereafter. Assessment of iron content by T2* MRI in the liver and myocardium before starting chelation therapy and to monitor the clearance of iron overload from organs. Screening for infections transmitted with donor blood components (determination of antibodies to hepatitis B virus surface antigen (HBsAg) in blood; determination of antibodies to hepatitis C virus in blood; determination of class M and G antibodies (IgM, IgG) to human immunodeficiency virus HIV-1 in blood; determination of class M and G antibodies (IgM, IgG) to human immunodeficiency virus HIV-2 in blood), monthly in case of regular transfusions, annually in case of infrequent transfusions. Assessment of visual acuity and hearing before starting chelation therapy and annually thereafter. Assessment of skeletal bone mineral density by X-ray densitometry annually starting from adolescence.

Appendix G. Assessment Scales, Questionnaires, and Other Evaluation Tools

Appendix G1. E/β-Thalassemia Severity Scoring Scale

Russian title: E/β-Thalassemia Severity Scoring Scale

Original title: A scoring system for the classification of b-thalassemia/HbE disease severity

Source (official developers' website, publication with validation): [199]

Type: rating scale

Purpose: assessment of E/β-thalassemia severity

Interpretation: E/β-thalassemia is considered mild with a total score of less than 4, moderate with a score of 4–7, and severe with more than 7 points.

Appendix G2. Criteria for Subdividing Thalassemia into Transfusion-Dependent (TDT) and Non-Transfusion-Dependent (NTDT) Forms

Russian title: Criteria for Subdividing Thalassemia into Transfusion-Dependent (TDT) and Non-Transfusion-Dependent (NTDT) Forms

Original title (if applicable):

Source (official developer website, validation publication):

Type (underline):

- rating scale

- index

- questionnaire

- other (specify)

Purpose: subdivision of the disease depending on the need for regular blood transfusions

Contents:

Criteria for subdividing thalassemia into transfusion-dependent (TDT) and non-transfusion-dependent (NTDT) forms (each criterion is assigned 1 point):

- grade 2–3 anemia up to 2 years of age

- anemia affects quality of life

- average annual (baseline) Hb <70 g/L

- pronounced hepatosplenomegaly (more than 5 cm below the costal margin)

- physical development delay (below the 10th percentile)

- frequent intercurrent infections

Interpretation: with 4 or more points, thalassemia is classified as the TDT form, and with less than 4 points as the NTDT form.