To date, more than four and a half thousand hereditary diseases are known, and each case has a solid evidence base that the disease is inherited, and nothing else.. But, despite the high level of development of diagnostics, not all genetic pathologies have been studied to the extent of biochemical reactions.. Nevertheless, the main mechanisms for the development of hereditary diseases are known to modern science, according to the Internet publication for girls and women from 14 to 35 years old Pannochka. net There are three basic types of mutations:.

Genetic;

Chromosomal;

Genomic (predominantly sex-linked).

The fundamental genetic laws of Mendel determine dominant and recessive genes. After fertilization, fetal cells contain half of the mother's genes and half of the father's genes, making pairs - alleles. There are not so many genetic combinations: only two. Defining traits appear in the phenotype. If one of the mutated allele genes is dominant, the disease manifests itself. The same thing happens with the dominant pair. If such a gene is recessive, this is not reflected in the phenotype in any way.. The manifestation of hereditary diseases transmitted by a recessive trait is possible only if both genes carry pathological information.

Chromosomal mutations are manifested by a violation of their division during meiosis. As a result of duplication, additional chromosomes appear: both sex and somatic.

Sex-linked hereditary anomalies are transmitted through the sex X chromosome. Since in men it is presented in the singular, all males in the family have manifestations of the disease.. Whereas women with two sex X chromosomes are carriers of a damaged X chromosome. For manifestations in women of a hereditary disease linked to sex, it is necessary that the patient inherit both defective sex chromosomes. It happens quite rarely.

Biology of hereditary diseasesManifestations of hereditary pathology depend on many factors. The traits inherent in the genotype have external manifestations (affect the phenotype) under certain conditions. In this regard, the biology of hereditary diseases divides all genetically determined diseases into the following groups:.

Manifestations that do not depend on the external environment, upbringing, social conditions, welfare: phenylketonuria, Down's disease, hemophilia, sex chromosome mutations;

Hereditary predisposition, which manifests itself only under certain conditions. Environmental factors are of great importance: the nature of nutrition, occupational hazards, etc.. These diseases include: gout, atherosclerosis, peptic ulcer, arterial hypertension, diabetes mellitus, alcoholism, tumor cell growth.

Sometimes, signs of even non-hereditary diseases are found in children of sick people.. This is facilitated by the same susceptibility of relatives to certain factors.. For example, the development of rheumatism, the causative agent of which has nothing to do with genes and chromosomes. However, children, grandchildren and great-grandchildren are also susceptible to systemic connective tissue damage.? - hemolytic streptococcus. Chronic tonsillitis accompanies many people all their lives, but does not cause hereditary diseases, while those who have relatives with rheumatic lesions of the heart valves develop a similar pathology.

Causes of hereditary diseases The causes of hereditary diseases associated with gene mutations are always the same: gene defect - enzyme defect - lack of protein synthesis. As a result, substances accumulate in the body that should have been converted into necessary elements, but in themselves, as intermediate products of biochemical reactions, are toxic..

For example, the classic hereditary disease, phenylketonuria, is caused by a defect in a gene that regulates the synthesis of an enzyme that converts phenylalanine to tyrosine.. Therefore, with phenylketonuria, the brain suffers.

Insufficiency of lactase causes intestinal upset. Intolerance to raw cow's milk is a fairly common phenomenon, and it also applies to hereditary diseases, although, under certain conditions, compensation may occur in some people, and lactase production is improving due to the active "

Chromosomal abnormalities appear regardless of conditions. Many children are simply not viable. But Down's disease refers to those hereditary diseases in which the external environmental conditions can be so favorable that patients become full members of society..

Defects in the division of sex chromosomes are not accompanied by fatal complications, since they do not affect somatic signs. All vital organs in such hereditary diseases do not suffer. Damage is found at the level of the genital organs, and often only internal. Sometimes goes without them. For example, in triplo-ex syndrome, when a woman has an additional X chromosome, the ability to conceive is preserved. And babies are born with a normal set of sex chromosomes. A similar situation with an additional Y-chromosome in men.

The mechanism of development of hereditary diseases lies in the combination of genes: dominant and recessive. Their different combination is unequally manifested in the phenotype.

For the development of the disease, one mutated dominant gene is sufficient, or a pathological recessive pair in one allele.

Prevention of hereditary diseasesPrevention of manifestations of genetic pathology is carried out by specialists of genetic centers. In large cities, women's clinics have special offices of geneticists who provide counseling to future couples.. Prevention of hereditary diseases is carried out by compiling genealogical maps and decoding special analyzes.

neboleem. net.