HYPERHOMOCYSTEINEMIA AND FOLATE CYCLE GENES IN GIRLS AND BOYS LIVING NEAR THE CHERNOBYL EXCLUSION ZONE

Abstract

The state of hyperhomocysteinemia (the level of the sulfur-containing amino acid homocysteine – Hcy in the blood over 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 Ecological Programs around the Chernobyl Exclusion Zone: Development, training and coordination of health-related projects" and the Rhone-Alpes Regional Council (France). Since numerous studies have noted hyperhomocysteinemia in severe diseases in adults, it is necessary to investigate its etiopathogenesis in the body of children under constant radiation exposure. At the same time, it is important to determine the participation in this pathological process of the genes of the folate cycle, which exchanges Hcy. The purpose of this studywas a comparative analysis of the manifestation of hyperhomocysteinemia in boys and girls living near the ChEZ, taking into account the genes that control the folate cycle. Research methods. The results of a laboratory examination of 690 children (368 girls and 322 boys) aged 8-17 from Ivankov and Polessky districts of the Kyiv region of Ukraine were used. Immunochemical, genetic and statistical research methods were used. Results. Statistical differences in the carriage of polymorphic alleles of the folate cycle (FC) genes, blood Hcy levels, the proportion of hyperhomocysteinemia levels, as well as correlations between Hcy values and B6, B9, B12 vitamins in the blood of the examined boys and girls were studied. Sex differences in the proportion of polymorphic alleles of the FC genes have not been established. In the general group of children, hyperhomocysteinemia was detected in 62.46 % of cases, while in the group of girls – in 53.80 % of cases, in the group of boys – in 72.36 % (t = 5.16; p = 0.000001). In most genetic subgroups of boys, the level of Hcy in the blood and the proportion of cases of hyperhomocysteinemia were statistically large compared with similar subgroups of girls. Despite the fact that the largest proportion of cases of hyperhomocysteinemia was associated with a homozygous variant of the T/T risk allele of the MTHFR:677 genetic polymorphism, in most genetic subgroups, including those that included only neutral FC alleles, this condition occurred in 50 or more % of cases. Conclusions. The high proportion of cases of hyperhomocysteinemia in children of both sexes may be associated with the constant exposure to long-lived radionuclides 137Cs, 90Sr, 241Am contained in the soils and plants of the ChEZ and adjacent areas. The lower level of Hcy in the blood and the proportion of cases of hyperhomocysteinemia in the group of girls, compared with the group of boys, is associated with a higher content of vitamin B12 in their blood and a more intense functioning of the transsulfuration reaction cycle. The results obtained can be used in the organization of preventive and rehabilitation measures for the child population in the territory affected by radiation exposure.