Diseases with hereditary predisposition

Diseases with hereditary predisposition have differences from gene diseases, which consist in the need to influence the human body environmental factors, so that these diseases are manifested. According to the genetic nature of the disease with hereditary predisposition are divided into 2 groups.

1. Monogenic diseases with hereditary predisposition.

This group of diseases is characterized by the fact that predisposition is determined by only one gene, that is, it is associated with a mutation of this gene. It includes: neurofibromatosis, Marfan syndrome, familial hypercholesterolemia, imperfect osteogenesis, atrophic myotonia, achondroplasia, adenomatous polyposis of the large intestine, Huntington's disease, polycystic kidney disease, cystic fibrosis, hemoglobinopathy. For the manifestation of signs of the disease, the obligatory effect of the environmental factor is necessary. This factor is usually accurately identified and treated with respect to this disease as specific.

2. Polygenic diseases with hereditary predisposition.

This group of diseases is determined by several genes, each of which is more normal than pathologically altered. The definition of these genes is very difficult. It includes: diabetes, gout, cleft lip, cleft palate, which are of a family nature. Their pathological manifestation they carry out when interacting with a whole complex of environmental factors. Such diseases are called multifactorial diseases, that is, they develop under the influence of a large number of factors, both external and internal. In this case, the relative role of genetic factors and environmental factors is different not only for this disease, but for every individual case of the disease.

These features make these diseases different in terms of both genetics and significance in human pathology. The first group of diseases is relatively small, the methods of Mendelian genetic analysis are applicable to them, their prevention and treatment are sufficiently definite and in some cases effective. Considering the main role of the environment in their manifestation, these diseases are considered as hereditary conditioned pathological reactions to the action of external factors.

Multifactorial diseases account for 90% of chronic non-infectious diseases of various human systems and organs. Analysis of these diseases to clarify the role of individual genes and their interaction with environmental factors is very difficult task, so in their treatment and prevention of genetics to date has not made a significant contribution.

In this feature of multifactorial diseases is the complexity of genetic analysis, the limited possibilities of clinical genealogical and twin research methods, the need to apply complex mathematical and biological methods to clarify the role of specific genes and environmental factors in the development of these diseases. Numerous materials of genealogical and twin analyzes, accumulated over the years of studying diseases with hereditary predisposition, only testify to the significance of heredity in the onset of this disease, but do not decode either the genes or the type of their transmission.

From the features of the development of multifactorial diseases follows a wide variety of their manifestations from subtle and even hidden forms to difficult and difficult to treat. The diversity of the genetic basis of each disease, based on the individuality of each organism, makes it possible to explain such features of multifactorial diseases as variability( even within a single family) of the onset of the disease, its development, the spectrum of manifestations of the disease and the degree of their severity. With these features, there are also significant differences in the incidence of different diseases and their forms within the population.