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Pathophysiology · Chapter 21. Typical Pathology Forms of the Blood System

Thalassemia

Thalassemia

Thalassemia is a group of hereditary blood disorders caused by impaired quantitative synthesis of globin chains. The deficiency of these chains leads to their excessive accumulation, destruction of red blood cells, and the development of severe anemia.

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Core PathologyImbalance of globin chains leading to ineffective erythropoiesis.
Genetic BasisMutations in genes responsible for the synthesis of alpha or beta globin chains.
Key FeatureAccumulation of unbalanced globin chains in the cytosol of erythroid cells.
Main FormsAlpha-thalassemia (chromosome 16) and beta-thalassemia (chromosome 11).
2 min readFor medical studentsUpdated 09/24/2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

Pathomechanism

The pathogenesis is based on a primary deficiency of one of the globin chains. Excess, "unpaired" globin chains cannot incorporate into hemoglobin and precipitate within the cytosol of erythroid cells, forming aggregates (Heinz bodies). This leads to two critical consequences:

  1. Ineffective erythropoiesis: destruction of erythroblasts directly in the bone marrow.
  2. Extravascular hemolysis: premature destruction of circulating reticulocytes and erythrocytes in the spleen.

The result is marked erythropenia and anemia.

Classification

The disease is classified depending on the affected chain:

  • Alpha-thalassemia: determined by 4 genes on chromosome 16. Severity ranges from asymptomatic carrier state (1 gene) to lethal hydrops fetalis (4 genes).
  • Beta-thalassemia: determined by 2 genes on chromosome 11. There are three forms:
  • Thalassemia minor: mutation of 1 gene, mild course.
  • Thalassemia intermedia: partial impairment of expression of 2 genes.
  • Thalassemia major (Cooley's anemia): complete cessation of expression of 2 genes, requires regular blood transfusions.
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Principles of therapy

Treatment is structured at three levels:

  1. Etiotropic: targeting factors that disrupt the proliferation and differentiation of blood cells.
  2. Pathogenetic: aimed at interrupting the mechanisms of anemia, combating hypoxia, hemosiderosis, and correcting acid-base balance disorders.
  3. Symptomatic: relief of anemia sequelae (headaches, sleep disturbances).

Briefly: answers to topical questions

What etiotropic treatment methods for thalassemia are used in practice?

Etiotropic treatment aims to eliminate or halt the cause of the disease.

Among the methods directly indicated in the sources:

  • in major β-thalassemia, the radical treatment is allogeneic hematopoietic stem cell transplantation; it is referred to as the only curative method;
  • for diseases caused by genomic alterations, gene therapy is indicated as a method for correcting genetic defects, though it remains in the stage of development, clinical trials, and partial application.
How to memorize

Alpha — 4 genes (like the 4 cardinal points), Beta — 2 genes (like the 2 sides of a coin).

Class and exam questions

Why does anemia develop in thalassemia?

Anemia occurs due to the destruction of erythroid cells in the bone marrow (ineffective erythropoiesis) and accelerated destruction of defective erythrocytes in the spleen.

What is the difference between minor and major beta-thalassemia?

The minor form is caused by a mutation in a single gene and runs an almost asymptomatic course. The major form (Cooley's anemia) is caused by the complete knockout of two genes and requires regular blood transfusions.

What are Heinz bodies?

These are aggregates of excess globin chains that precipitate in the erythrocyte cytosol, damaging the cells and triggering hemolysis.

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What else to study on this topic

  • Differential diagnosis of microcytic anemias.
  • Mechanisms of hemosiderosis development during frequent blood transfusions.
  • Features of laboratory diagnostics (sideroblasts, anisocytosis, hypochromia).
  • Genetic aspects of mutation inheritance on chromosomes 16 and 11.

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Other topics in "Chapter 21. Typical Pathology Forms of the Blood System"

Blood volume changesBlood lossErythrocytosis and erythremiaAnemiaHemolytic anemiasB12- and folate-deficiency anemiasIron-deficiency anemiasLeukopeniasLeukocytosisHemostasis pathologyDIC syndromeLeukemiasHypervolemia and hypovolemiaBlood loss and posthemorrhagic statesErythrocytosesClassification of anemiasLeukocytosis and leukopeniaChanges in differential leukocyte countPathology of the hemostatic system: thrombocytopenias and thrombocytopathiesThrombotic syndromeHemorrhagic syndromeStages of DIC syndromeHemoblastosesClassification of hemoblastoses
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