Hereditary diseases - diseases, the emergence and development of which is associated with defects in the software cell apparatus, inherited through the gametes (eggs and sperm).
The basis of hereditary diseases are abnormalities (mutations) of hereditary information - chromosome, gene, and the mitochondrial. Hence - the classification of hereditary diseases:
Among the hereditary diseases, developing as a result of mutation, is traditionally divided into three subgroups:
- monogenic hereditary diseases
- polygenic hereditary diseases
- chromosomal aberrations
From hereditary diseases to be distinguishedcongenital diseases, which are caused by prenatal injuries caused by, for example, infections (syphilis or toxoplasmosis), or exposure to other damaging factors on the fetus during pregnancy.
Many genetically determined diseases manifest themselves immediately after birth, and after a sometimes very long time.
Monogenic hereditary diseases
Monogenic diseases are inherited in accordance with thethe laws of classical Mendelian genetics. Accordingly, for their genealogical research reveals one of the three types of inheritance: autosomal dominant, autosomal recessive and sex-linked inheritance.
This is the most extensive group of inheriteddiseases. Currently, more than 4000 variants described monogenic hereditary diseases, most of which is quite rare (eg, frequency of sickle cell anemia - 1/6000).
A wide range of monogenic diseases formhereditary metabolic disorders, the occurrence of which is associated with a gene mutation that controls the synthesis of enzymes and is responsible for their deficiency or defect structure - fermentopathy.
Polygenic hereditary diseases
Polygenic inherited disease difficult. For them, the question of inheritance can not be resolved on the basis of Mendel's laws. Previously, such hereditary diseases characterized as a disease with genetic predisposition. These diseases include diseases such as cancer, diabetes, schizophrenia, epilepsy, ischemic heart disease, hypertension, and many others.
Chromosomal disease caused by a flagrant violation ofhereditary apparatus - changes in the number and structure of chromosomes. A typical reason in particular - alcohol intoxication parents at conception ( "drunken kids"). These include Down syndrome, Klaynfeltera, Shereshevskii - Turner, Edwards, "cat cry" and others.
Diagnosis and treatment of hereditary diseases
In recent years, the impression thatthe relatively high frequency of genetic disorders due to certain advantages of "mutants" in relation to the factors of natural selection or "predisposition to the disease."
Treatment of hereditary diseases include symptomatic treatment, and gene therapy.
A hereditary disease characterized by a variety ofsymptomatic manifestations, and treatment is largely symptomatic. Certain metabolic correct assignment of special diets designed to reduce toxic substances in the body, which is caused by the accumulation of mutations in certain genes. For example, when administered bezalaninovuyu PKU diet.
To alleviate the symptoms of hereditary diseases,associated with a particular protein defect, it is administered intravenously such functional form that does not cause an immune response. This replacement therapy used in the treatment of hemophilia, heavy combined immunodeficiency, and others. Sometimes, to compensate for specific lost functions carried out bone marrow transplantation and other organs. Existing therapy, unfortunately, in most cases, not effective enough.
In principle, the new method, effective andaimed at the destruction of the genetic causes of hereditary diseases is gene therapy. The method of gene therapy - introducing normal genes into defective cell.
The concept of gene therapy consist in thatmost radical way to deal with various kinds of diseases caused by changes in the genetic content of cells, treatment should be aimed directly at the correction or destruction of most of the genetic causes of the disease rather than its consequences.
Due to the fact that gene therapy isa new area of medical genetics and disease, who are trying to heal this way, very diverse, created many original approaches to this problem. Currently, research for gene therapy is mainly aimed at correction of genetic defects in somatic and germ cells do not, due to purely technical problems as well as safety reasons.