Gene diseases include a large group of diseases that arise as a result of changes in the structure of the gene. Let's find out what are the reasons for the development of such pathologies.
The majority of human genetic diseases are caused by mutations in structural genes that perform their function through the synthesis of polypeptides, in other words, proteins. Any gene mutation entails changes in the structure or amount of protein.
Such diseases begin with the primary effect of the mutant allele. If we try to schematically depict human gene mutations , then at first there will be a mutant allele that flows into a modified primary product, as a result of which a chain of biochemical processes takes place in the cell, resulting in changes in organs and tissues, and then the whole organism.
Considering gene diseases at the molecular level, the following options can be distinguished:
- production of excess gene product,
- synthesis of abnormal protein,
- lack of production,
- as well as the production of a reduced amount of primary product.
Gene diseases do not end at the molecular level. Their pathogenesis continues to develop at the cellular level. In this regard, it is worth noting that the organs of the whole as well as individual cell structures, such as membranes, peroxisomes, lysosomes, mitochondria, can become the point of application of the action of the altered gene in various diseases.
An important feature of gene pathologies is that their clinical manifestations, as well as the speed and severity of development, are determined at the level of the organism's genotype, environmental conditions, age of the patient, and the like.
A characteristic feature of gene pathologies is heterogeneity. This suggests that the phenotypic manifestation of such a disease can be due to both different mutations occurring within the same gene, and in different genes. This was first established in 1934 by a famous researcher in the field of genetics S.N.Davidenkov.
As for the monogenic forms of gene pathologies, then, according to the laws of G. Mendel, they are inherited. In turn, monogenic forms can be divided according to the type of inheritance, namely, autosomal recessive, autosomal dominant and linked to Y- or X-chromosomes.
All gene diseases can be classified according to a number of signs, and the most numerous group in this case will be hereditary metabolic diseases. Almost all of them belong to the autosomal recessive type. The cause of these pathological conditions is an insufficient amount of an enzyme that is responsible for the synthesis of amino acids. This includes pathologies such as phenylketonuria, ocular-skin albinism, as well as alkapturia.
The next large group of gene diseases is associated with metabolic disorders. Glycogen disease, galactosemia - these are examples that belong to this group.
The following are pathologies that are directly related to lipid metabolism, namely Gaucher disease, Nimann-Peak disease and the like.
Human gene diseases, in addition to those already indicated, are classified into
- hereditary diseases of pyrimidine and purine metabolism,
- pathologies associated with connective tissue disorders,
- hereditary disorders of circulating proteins,
- diseases that are directly related to metabolic disorders in red blood cells,
- hereditary pathologies of metal metabolism,
- as well as syndromes that cause disturbances in the absorption processes in the digestive system.
In addition to all of the above, we add that the establishment of the hereditary nature of the disease is carried out on the basis of the clinical genealogical method.