Gene mutations

Gene mutations are the reason for the formation of a group of diseases that is heterogeneous in terms of clinical manifestations, which is called "gene diseases". The total frequency of their occurrence in the human population is two to four percent.

The change (mutation) of genes is provoking to the development of many forms of hereditary diseases factor. In modern medicine, more than three thousand such pathologies are described. The most common manifestation of diseases is fermentopathy. It is believed that gene mutations can affect embryonic, transport and structural proteins. Pathological changes can be realized in different periods of ontogenesis (development). Most of them are typical for intrauterine (up to 25% of all hereditary pathologies) and for pre-pubertal (before puberty) period (about 45%). Genetic mutations are manifested in pubertal (puberty) and adolescence (about 25%). A relatively small amount (about 10%) of pathological changes is detected over twenty years.

Hereditary diseases are classified according to the type of inheritance (autosomal recessive, autosomal dominant and others), depending on the organ or system more involved in the pathological process (endocrine, neuromuscular, ocular and others), taking into account the nature of the metabolic defect (associated with Disorder of carbohydrate, mineral lipid metabolism, etc.). The independent group includes diseases that have arisen against the background of the incompatibility of the fetus and the mother in terms of antigens in the blood groups.

Provoked by the gametic mutations, pathologies are inherited in accordance with the laws of Mendel. Perhaps the emergence of new or development inherited from past generations of change. In such cases, pathological structures are distributed to all cells of the body.

Genetic mutations can appear in one of the cells at different stages of the zygotic cleavage. In such cases, the body becomes mosaic in this structure. In other words, in some cells a normal allele (the form of a gene) functions, and in others - a mutant allele. Domination of the mutation is manifested phenotypically (clinical signs) in the corresponding cells and provokes the development of the disease. At the same time, there is a sufficient probability of a less severe degree of pathology, in contrast to complete mutants.

Experts classify changes in functional and structural nature.

Structural gene mutations are divided into transitions - substitution of one purine base (organic organic compounds, purine derivatives) for another, or one pyrimidine base (organic compounds - pyrimidine derivatives) to another pyrimidine base; While the codon (the unit of the genetic code) changes only the one in which the replacement occurred. There is also such a thing as "transversion". In this case, the pyrimidine bases are replaced by purine ones or vice versa. This also changes the codon in which the replacement occurred. In addition, there is also a mutation by shifting the reading frame. In this case, a deletion (deletion) or insertion (insertion) of several or one pair of nucleotides occurs. In accordance with the site of deposition or insertion, more or fewer codons may change.

Mutations in functional genes are a change in the untranscribed (encoding) part in the DNA molecule. This provokes a disorder in the regulation of the functioning of structural elements. As a result, the synthesis rate of the corresponding protein may be increased or decreased to varying degrees.