Medical Genetics - V. M. Zaporozhan 2005

Multifactorial Diseases
Ecogenetics
Subject Matter of Ecogenetics

Every living Organism develops and exists in close interaction with its environment. The genetically determined response of The Human Body to various environmental agents is the subject of ecogenetics, a branch of genetics that studies the IMPACT OF ENVIRONMENTAL factors on heredity. METABOLISM/2.html">THE CONCEPT OF ecogenetics was first proposed by Brewer (1971).

Ecogenetics studies 2 types of effects:

— alteration in the phenotypic expression of certain alleles when the organism is exposed to specific factors (ecogenetic syndromes);

— alteration of genetic material under the Influence of Environmental factors (induced mutagenesis).

Throughout evolution, the human living environment has gradually changed. The organism has adapted to these changes, firstly, through a wide reaction norm, and secondly, through genotype alterations resulting from Mutations and subsequent Selection. In the course of evolution, a relative harmony between environmental conditions and human species characteristics has emerged.

Under The Influence of selection, populations have developed a broad hereditary polymorphism of genes that ensure interaction with the environment. At least 25% of genes determining Antigens, Enzymes, and receptors are represented by polymorphic systems with more than 2 alleles. Many of these have spread in certain populations due to a selective advantage, while others are the result of Genetic Drift. Some of them do not manifest phenotypically.

The modern era is characterized by a high pace and intensity of environmental changes. A massive amount of chemicals enters the environment, including those found in food products (food additives, preservatives, colorants, etc.), household chemicals, and industrial waste. Humans have never encountered many of these substances during their evolutionary history. Due to The Emergence of these novel environmental factors, genes that were previously "silent" begin to manifest phenotypically under the new conditions and become subject to natural selection.

In some cases, these reactions can be pathological and lead to so-called ecogenetic disorders. Ecogenetic pathological reactions (ecogenetic disorders) are defined as genetically determined pathological responses to environmental factors (Table 7.10). Potentially toxic environmental factors cause diseases not in the entire population, but only in the subset of individuals genetically predisposed to such exposure.

Table 7.9. Susceptibility genes for Multifactorial Diseases (V. S. Baranov et al., 2000)

Table 7.10. Examples of ecogenetic pathological reactions (N. P. Bochkov, 2001)