Objective: Methionine synthase (MS) is the key enzyme in the homocysteine metabolism. To investigate the relations of MS gene variation with occurrence of congenital heart disease (CHD).
Methods: 186 CHD patients (0-31 years old) were selected as case group and 103 normal population as control. For all subjects the gene polymorphism at MS A2756G locus was analysed by PCR-RFLP method, and the serum folic acid/vitamin B12 levels were detected by radio-immunity assay.
Results: The heterozygotes (+/-) were detected in the subjects but without homozygotes (+/+). In control group the frequencies of (+/-) genotype and (+) allele were 10.7% and 5.3%, lower than Caucasian and Japanese population. In case group the frequencies of (+/-) genotype and (+) allele were 9.1% and 4.6%, without significantly different from control. The odds ratio of (+/-) genotype was 0.84 (0.35, 2.01). The genotype distributions in different types of CHD were also not apparently different with control. The serum vitamin B12 level was decreased in case group compared with control (336.66 pmol/L vs 465.72 pmol/L, P > 0.05), but the serum folic acid level no different. Also there were not significant difference for folic acid/vitamin B12 levels between different genotypes in case group.
Conclusion: The results indicated that there was not apparent association between MS gene A2756G locus variation with CHD and serum folic acid/vitamin B12 levels. It need further investigations.