Abstract
High levels of plasma homocysteine are associated with an increased risk of many health conditions influenced by both environmental and genetic factors. The objective of this study was to provide the geographical distribution of folate pathway genetic polymorphisms in Mexico and the comparison with the reported frequencies in different continental populations. This study included the analysis of the genotypic frequencies of eight polymorphisms in genes of the folate/homocysteine metabolic pathway in 1,350 Mestizo and Amerindian subjects from different regions in Mexico and 836 individuals from European, African and Asian populations of the 1,000 Genomes Project. In Mexican Mestizo and Amerindian populations, the MTHFR C677T risk genotype (TT) was highly prevalent (frequency: 25 and 57 %, respectively). In Mestizos, the frequency showed clear regional variation related to ancestry; the Guerrero subpopulation with the highest Amerindian contribution had the highest TT frequency (33 %). The MTHFD1 G1958A AA risk genotype was also enriched in Mexican Mestizos and Amerindians (frequency: 34 and 58 %, respectively), whereas in African and Asian ancestry populations the frequency for AA was low (~4 %). All together risk genotypes showed regional differences, and Sonora had significantly different genetic frequencies compared with the other regions (P value <0.05). Our study illustrates differential geographical distribution of the risk variants in the folate/homocysteine metabolic pathway relative to ethnic background. This work supports that certain areas of the world have increased needs for folic acid and vitamin B supplementation, and this information needs to be considered in public health guidelines and eventually policies.Electronic supplementary materialThe online version of this article (doi:10.1007/s12263-014-0421-7) contains supplementary material, which is available to authorized users.
Highlights
Folates are a group of molecules that belong to the vitamin B family, differing by their oxidation state, number of glutamic acid moieties and one-carbon substitutions (Forges et al 2007)
To better understand the distribution of this and other variants in the folate-mediated one-carbon metabolism pathway in a highly admixed population such as Mexicans, we describe and compare the allele and genotype frequencies of FOLH1 T484C, MTR A2756G, MTHFD1 G1958A, MTRR A66G, methylenetetrahydrofolate reductase gene (MTHFR) A1298C, MTHFR C677T, SLC19A1 A80G and TCN2 C77G
The concordance between our frequency genotyping data obtained by allelic discrimination with TaqManÒ, and those acquired from the Mexican Genome Diversity Project using Illumina 510 and 550 K arrays was high (=99.43 %)
Summary
Folates are a group of molecules that belong to the vitamin B family, differing by their oxidation state, number of glutamic acid moieties and one-carbon substitutions (Forges et al 2007). They are part of the commonly known folate-mediated one-carbon metabolism pathway, a system consisting of a number of interdependent metabolic cycles, that are necessary in a large number of biochemical 421 Page 2 of 14. Folic acid supplementation during the periconceptional period reduces greatly the risk of NTDs The benefit of folic acid supplementation in reducing the risk for cardiovascular diseases (CVD) by decreasing the homocysteine levels is not clear, revealing a more complex relationship between vitamin intake levels, homocysteine and CVD (Bonaa et al 2006; Homocysteine Studies 2002; Toole et al 2004; Lonn et al 2006)
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