Table 3. Frequencies of MTHFR gene polymorphisms in the mothers of the children with CHD.

Genotype	Control, n (%)	Case, n (%)	χ2 value	P	OR (95% CI)
CC	71 (30.0)	50 (14.4)	–	–	–
CT	108 (45.6)	156 (45.1)	–	–	–
TT	58 (24.4)	140 (40.5)	15.33	<0.0001	2.097 (1.455–3.024)

MTHFR, methylenetetrahydrofolate reductase; CHD, congenital heart disease.