Distribution of MTHFR A1298C polymorphism among populations from 9 provinces in China.

Abbreviation: MTHFR, methylenetetrahydrofolate reductase; AA, “wild-type” homozygosity; AC, heterozygosity; CC, mutant homozygosity; CI, confidence interval.aThe 1298C allele frequencies were significantly different among the 9 populations (χ2 = 406.85, PbThe 1298CC genotype frequencies were significantly different among the 9 populations (χ2 = 130.73, P*The 1298C allele frequencies were significantly different from the southern populations (χ2 = 5.40, P = 0.0201).#The 1298 CC genotype frequencies were significantly different from the southern populations (χ2 = 4.27, P = 0.0389).