[Polymorphisms of methylenetetrahydrofolate reductase gene among women of childbearing age from Shiyan area].

Objective: To assess the association of methylenetetrahydrofolate reductase (MTHFR) gene 677C to T polymorphism with blood homocysteine (Hcy) level among women of childbearing age from Shiyan area.

Methods: PCR-chip hybridization was used to determine the genotype of MTHFR 677C to T, and a biochemical assay was used to determine the total Hcy level among 428 healthy women of childbearing age. Association of MTHFR 677C to T with total Hcy level was assessed.

Results: Heterozygous CT mutation was most common form for the MTHFR 677C to T polymorphisms and amounted for 49.77% among the group, while the CC wild type and homozygous TT mutation respectively accounted for 30.61% and 19.63%. These gave a frequency of 44.51% for the 677T allele. The dominant genotype among different age groups were the CT type. Of note, the proportion of MTHFR 677CC is higher in women above 30 years of age. The distribution of MTHFR 677C to T genotypes has differed significantly among different age groups (P<0.05). Compared with those with wild type alleles, carriers of MTHFR mutations had a higher plasma Hcy level. The genotypic frequencies of MTHFR C677T in Shiyan region differed significantly from those of Sichuan, Hebei, Henan and Shandong (P<0.05) but were similar to those of Jiangsu, Guangdong, Ningxia and Xinjiang.

Conclusion: The distribution of MTHFR C677T polymorphism among women of childbearing age in Shiyan area is influenced by age and is geographically specific and associated with plasma Hcy level. Nearly 50% of women have carried the high risk alleles, for whom folic acid supplementation is crucial for the reduction of birth defect rate.