Etiological principle of therapy
Goal: complete elimination of the genetic cause of the disease and associated risk factors.
Main method: gene therapy. It involves targeted correction of identified genetic defects at the DNA level. Today, this direction is considered the most promising, but most methods are still at the stages of laboratory development, clinical testing, or are only partially used in medical practice.
Pathogenetic principle of therapy
Goal: to interrupt the disease development mechanisms (breaking the links of pathogenesis) triggered by the mutation. This approach is implemented through three main strategies:
- Replacement therapy. The patient is artificially administered a substance that the body is unable to synthesize independently due to a gene defect.
- Examples: regular insulin injections in diabetes mellitus, administration of specific enzymes in glycogenoses and aglycogenoses, as well as the use of antihemophilic globulin in hemophilia.
- Metabolic correction. Allows neutralizing biochemical disruptions in three ways:
- Restriction of the intake of substances that are not metabolically absorbed (a strict diet excluding phenylalanine or lactose).
- Stimulation of the excretion of metabolites that accumulate in excess in the body (accelerated excretion of cholesterol or phenylpyruvic acid).
- Regulation of enzyme activity (suppression of creatine phosphokinase activity in certain myodystrophies or activation of blood lipoprotein lipase in hypercholesterolemia).
- Surgical correction of defects. Surgical intervention to compensate for metabolic disorders.
- Example: creation of a vascular shunt between the inferior vena cava and the portal vein in patients with hepatogenic glycogenoses.
Symptomatic therapy
Goal: management of disease manifestations that worsen the patient's condition. This approach does not eliminate the genetic cause of the pathology, but is critically important for relieving symptoms and improving quality of life.
Examples of clinical application:
- Cystic fibrosis: prescription of special medications (mucolytics) that effectively reduce the viscosity of thick secretions of exocrine glands.
- Limb malformations: in polydactyly or syndactyly, surgeons remove extra fingers or dissect skin folds between them.
- Congenital defects: performing reconstructive plastic surgeries for anatomical facial defects, as well as complex surgical correction of congenital heart and vascular defects.
Preventive direction of medical genetics
Goal: to prevent the birth of sick children or maximally reduce the risk of manifestation of diseases whose etiology is genomic changes.
Preventive measures are strictly focused on three categories of changes in the genome:
- Mutations occurring directly in the parents' germ cells (gametes).
- Pathological changes inherited from previous generations (familial history).
- Changes that manifest against the background of genetic predisposition under the trigger influence of unfavorable environmental factors.
Briefly: answers to topical questions
What types of vectors are used for DNA delivery in gene therapy?
Retroviral vectors are used for DNA delivery in gene therapy. The treatment process involves creating a special retrovirus containing vector DNA with an integrated normal allele of the required gene. Upon infecting isolated patient cells (e.g., leukocytes) with the created retrovirus, integration occurs: the viral DNA fragment with the normal gene is integrated into the cell chromosomes for subsequent transgene expression.
What invasive methods of prenatal diagnostics for hereditary diseases exist?
Prenatal (antenatal) diagnostic procedures for hereditary diseases in the fetus listed in the sources include:
- chorionic villus sampling;
- placental biopsy — placentocentesis;
- amniocentesis;
- cordocentesis;
- choriocentesis.
Laboratory analysis of the material includes cytogenetic study (karyotype) and molecular genetic methods.
To remember the three main principles of treatment, use the acronym EPS: Etiological (eliminating the cause — fixing the gene), Pathogenetic (breaking the chain — supplying an enzyme or correcting metabolism), Symptomatic (relieving the condition — managing symptoms).
Class and exam questions
What is the essence of replacement therapy in hereditary diseases?
It consists of introducing a deficient substance into the body that is not synthesized due to a gene anomaly. A classic example is insulin injection in diabetes mellitus or enzymes in glycogenoses.
How can metabolism be corrected in genetic defects?
Metabolism is corrected in three ways: by restricting the intake of unabsorbable substances (e.g., excluding lactose), eliminating excess toxic metabolites, and pharmacologically regulating enzyme activity.
Does symptomatic therapy cure a hereditary disease?
No, symptomatic therapy does not eliminate the genetic cause of the pathology. Its main task is to eliminate symptoms that worsen the patient's condition and alleviate the clinical manifestations of the disease.
What else to study on this topic
- Gene therapy: modern methods of correcting genetic defects
- Pathogenesis and principles of treatment of glycogenoses and aglycogenoses
- Dietotherapy in hereditary metabolic disorders (phenylketonuria)
- Surgical methods for correcting congenital heart and vascular defects
- Preventive direction of medical genetics and the influence of environmental factors
Master the entire topic in the "Pathophysiology" course
This is a summary. The course covers everything tested in classes and exams.
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Other topics in chapter "Chapter 3. Forms of pathology caused by changes in the genome"
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