Gene mutations are the reason whythere is a formation of a heterogeneous group of diseases, 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 provocativeto 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 puberty (puberty) and youth (about 25%). A relatively small amount (about 10%) of pathological changes is detected over twenty years.
Hereditary diseases are classified by typeinheritance (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 a disorder of carbohydrate, mineral lipid exchange, etc.). To an independent group include diseases that have arisen against the background of incompatibility of the fetus and the mother for antigens in blood groups.
Provoked by 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 cellsat different stages of fragmentation of the zygote. In such cases, the body becomes mosaic in this structure. In other words, in some cells a normal allele (gene form) functions, and in others - a mutant allele. Domination of the mutation manifests itself phenotypically (clinical signs) in the corresponding cells and provokes the development of the disease. In this case, there is a sufficient probability of a less severe degree of pathology, in contrast to complete mutants.
Specialists classify changes in functional and structural nature.
Structural gene mutations are subdivided intoTransition - 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 less codons can be changed.
Mutations in functional genes arechange of the nontranscribed (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.
