Hereditary diseases of the nervous system

Hereditary diseases of the nervous system are a heterogeneous group of diseases that are caused by changes( mutations) at the gene level. Despite the wide variety of forms, all these diseases share similarities. Such common signs of hereditary diseases of the nervous system include: the variable age of the onset of illnesses, the involvement of many organs and systems in the pathological process, the gradual development and chronic( and in most cases, continuously progressive) course leading to disability and shortening of life.

Differences between various hereditary diseases of the nervous system are due to the different timing of the appearance of the first signs of a disease, the rate and duration of the course of the disease, in the large difference in appearance and severity. In addition, with various diseases, there is a different degree of resistance of the body to the treatment. The variety of manifestations of hereditary diseases of the nervous system is due primarily to genetic polymorphism, ie, the fact that the same diseases are caused by tens and even hundreds of different mutations in the same region of the gene. In this case, some patients have in their hereditary material a combination of two different pathological changes in the same region of the gene. The manifestation of a pathologically altered gene is influenced by the external environment and other genes of the given organism. Such genes are called modifier genes.

At the same time, the same syndrome in a nerve disease can be caused by mutations in different genes or sections of the same gene. This phenomenon is called genetic heterogeneity of hereditary diseases. In fact, in these cases we are talking about different forms of pathology, but they are united in one disease due to the great similarity of emerging manifestations. For the first time the genetic heterogeneity of hereditary diseases was noted and introduced by the term domestic neuroscientist SN Davidenkov. This happened in the 30's. XX century. Genetic heterogeneity can be traced through the use of clinical genealogy analysis, when it is revealed that in different families with the same form of disease different types of hereditary transmission are determined.