THE COMBINATION OF FOLATE CYCLE GENOTYPES AND HYPERHOMOCYSTEINEMIA IN CHILDREN LIVING NEAR THE CHERNOBYL EXCLUSION ZONE

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The state of hyperhomocysteinemia (the level of the sulfur-containing amino acid homocysteine (Hcy) in the blood is more than 10 μmol/l) was first detected in a large number of adolescent children living in areas located near the Chernobyl exclusion zone (ChEZ) during the implementation of the European Commission’s projects “Health and environmental programs around the Chernobyl exclusion zone: development, training and coordination of projects related to health” and the Rhone-Alpes Regional Council (France). Since numerous studies have noted hyperhomocysteinemia in severe diseases in adults, it is necessary to highlight the impact of environmental factors (exogenous factor) and the state of the genetic apparatus responsible for the functioning of Hcy metabolic cycles (endogenous factor). The purpose of this study was a comparative analysis of the proportion of hyperhomocysteinemia in subgroups of boys and girls from areas bordering the ChEZ, taking into account combinations of folate cycle (FC) genotypes. Subject and methods of research. The analysis was based on the results of a laboratory examination of 690 children (368 girls and 322 boys) aged 8-17 years in the Ivankovsky and Polessky districts of the Kyiv region of Ukraine. Immunochemical, genetic and statistical research methods were used. Results. The structure was studied and the proportion of hyperhomocysteinemia was assessed in the case of a combination of allelic variants of genetic polymorphisms of FC. Differences and features of the occurrence of hyperhomocysteinemia depending on gender were revealed. Conclusions. The occurrence of hyperhomocysteinemia in children living near the ChEZ can occur with a combination of homozygous variants of neutral alleles of genetic polymorphisms of FC, which indicates an external environmental impact, including a radiation factor. The presence in the genome of boys of combinations of risk alleles for FC polymorphisms, with the participation of MTHFR:677, as well as MTRR:A66G, contributes to an increase in the level of Hcy in the blood. Mutations in the FC genes (T/T MTHFR:677, C/T MTHFR:677 in combination with A/G MTRR:66), in which there is a violation of the activity of the enzymes of FC – methylenetetrahydrofolate reductase and methionine synthase reductase, are an internal factor contributing to the occurrence of hyperhomocysteinemia. In girls with a combination of heterozygotes and homozygotes of risk alleles for FC polymorphisms, increased amounts of Hcy are utilized in the cycle of trans-sulfurization reactions.