The minor allelic frequencies of the MTHFD1 1958G>A and MTHFR 1298A>C in our populations were similar to those reported from Southeast Asian population, suggesting a possible explanation for the prevalence of this malformation in these regions.
We evaluated five single-nucleotide polymorphisms (SNPs) in genes related to folic acid metabolism: methylenetetrahydrofolate reductase (MTHFR C677T and A1298C), solute carrier family 19, member 1 (SLC19A1 G80A), methionine synthase (MTR A2576G), and methionine synthase reductase (MTRR A66G), as risk factors for CTDs including various types of malformation, in a total of 193 mothers with CTD-affected offspring and 234 healthy controls in a Chinese population.