Role of parental folate pathway single nucleotide polymorphisms in altering the susceptibility to neural tube defects in South India.

AIM To investigate the role of four parental folate pathway single nucleotide polymorphisms (SNPs) i.e., methylene tetrahydrofolate reductase (MTHFR) 677C>T, MTHFR 1298A>C, methionine synthase reductase (MTRR) 66A>G and glutamate carboxypeptidase (GCP) II 1561C>T on susceptibility to neural tube defects (NTDs) in 50 couples with NTD offspring and 80 couples with normal pregnancy outcome. RESULTS Maternal MTHFR 677C-->T (odds ratio (OR): 2.69, 95% confidence interval (CI): 1.35-5.34) and parental GCP II 1561C-->T (maternal: OR: 1.89, 95% CI: 1.12-3.21 and paternal: OR: 3.23, 95% CI: 1.76-5.93) were found to be risk factors for a NTD. Both paternal and maternal GCP II T-variant alleles were found to interact with MTHFR 677T- and MTRR G-variant alleles in increasing the risk for NTD. Segregation of data based on type of defect revealed an association between maternal 677T-allele and meningomyelocele (OR: 9.00, 95% CI: 3.77-21.55, P<0.0001) and an association between parental GCP II 1561T-allele and anencephaly (maternal: OR: 2.25, 95% CI: 1.12-4.50, P<0.05 and paternal: OR: 4.26, 95% CI: 2.01-9.09, P<0.001). CONCLUSIONS Maternal MTHFR C677T and parental GCP II C1561T polymorphisms are associated with increased risk for NTDs. Apart from individual genetic effects, epistatic interactions were also observed.