Association of methylene tetrahydrofolate reductase (MTHFR) gene polymorphisms with serum folate, cobalanin and homocysteine concentrations in Greek adults

Methylene tetrahydrofolate reductase (MTHFR) is a key enzyme of homocysteine metabolism participating in the folate cycle. The aim of this study was to investigate the association of MTHFR C677T and MTHFR A1298C gene polymorphisms with serum folate, cobalamin (Cbl) and homocysteine (Hcy) concentrations in healthy Greek adults. The MTHFR C677T and A1298C gene polymorphisms were genotyped in 383 healthy Greek adults (199 men and 184 women) using polymerase chain reaction and reverse hybridization. Serum folate, Cbl and total Hcy (tHcy) levels were determined using immunoassays methods. Among the 383 individuals, 73 (19.1%) were normal (CC), 202 (52.7%) were heterozygous (CT) and 108 (28.2%) were homozygous (TT) regarding the MTHFR C677T gene polymorphism, while 263 (68.7%) were normal (AA), 105 (27.4%) were heterozygous (AC) and 15 (3.9%) were homozygous (CC) regarding the MTHFR A1298C gene polymorphism. The overall C and T allele frequency for the MTHFR C677T gene polymorphism was 45.4% and 54.6%, respectively, while the overall A and C allele frequency for the MTHFR A1298C gene polymorphism was 82.3% and 17.6%, respectively. The MTHFR C677T and not the A1298C gene polymorphism had a significantly influence on serum folate and tHcy levels. The individuals with 677TT genotype had significantly lower serum folate and significantly higher serum tHcy levels than individuals with 677 CC or CT genotypes. Serum folate and tHcy levels are influenced by the existence of the MTHFR C677T gene polymorphism (mainly 677TT genotype). Individuals with low serum folate levels and/or high serum tHcy levels should be further investigated for a possible existence of MTHFR C677T and not A1298C gene polymorphisms, with aim to determine the suitable treatment.