What causes genetic diseases
Genetic diseases include a large group of diseases that arise as a result of a change in the structure of the gene. Let's find out what are the causes of the development of such pathologies.
The majority of human genetic diseasesare caused by mutations in structural genes that perform their function through the synthesis of polypeptides, in other words - proteins. Any gene mutation leads to changes in the structure or amount of protein.
Such diseases begin with a primary effectmutant allele. If one attempts to schematically depict human gene mutations, the mutant allele will first be located, which will flow into the altered primary product, resulting in a chain of biochemical processes in the cell, resulting in changes in organs and tissues, and then of the whole organism as a whole.
Considering the genetic diseases at the molecular level, we can distinguish the following variants of them:
- production of excess amount of gene product,
- synthesis of abnormal protein,
- lack of production,
- as well as the production of a reduced amount of the primary product.
Gene Disease does not end with molecularlevel. Their pathogenesis continues its development at the cell level. In this regard, it should be noted that the point of application of the action of the altered gene for various diseases can be both organs in general, and individual cellular structures, such as membranes, peroxisomes, lysosomes, mitochondria.
An important feature of gene pathologies isthat their clinical manifestations, as well as the speed and severity of development is determined at the level of the body's genotype, environmental conditions, the patient's age, and the like.
A characteristic feature of gene pathologies isheterogeneity. This suggests that the phenotypic manifestation of such a disease can be due to both the different mutations occurring within one gene and in different genes. This was first established in 1934 by a famous researcher in the field of genetics, S. N. Davydenkov.
As for the monogenic forms of gene pathologies,then, according to the laws of G. Mendel, they are inherited. In turn, the 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 by seriessigns, and the most numerous group in this case will be hereditary metabolic diseases. Virtually all of them belong to the autosomal recessive type. The reason for these pathological conditions is the inadequate quantity of one or another enzyme, which is responsible for the synthesis of amino acids. This includes such pathologies as phenylketonuria, eye-skin albinism, as well as alkaponuria.
The next large group of gene diseases is associated with metabolic disorders. Glycogen disease, galactosemia - these are examples related to this group.
Following are pathologies that are directly related to lipid metabolism, namely, Gaucher disease, Niemann-Pick disease and the like.
Human genetic diseases, in addition to those already mentioned, are classified into
- hereditary diseases of pyrimidine and purine metabolism,
- pathologies associated with disorders of connective tissue,
- hereditary disorders of circulating proteins,
- diseases that are directly related to metabolic abnormalities in erythrocytes,
- hereditary pathologies of metabolism of metals,
- as well as syndromes that cause disturbances in absorption processes in the digestive system.
In addition to all the above, we add that the establishment of the hereditary nature of the disease is based on the clinical genealogical method.