General maternal medication use, folic acid, the MDR1 C3435T polymorphism, and the risk of a child with a congenital heart defect
Objective We sought to investigate maternal and child functional MDR1 C3435T polymorphism, periconception medication, folic acid use, and the risk of a congenital heart defect (CHD) in the offspring. Study Design MDR1 3435C>T genotyping was performed in 283 case triads (mother, father, child) and 308 control triads. Information on periconception medication and folic acid use was obtained through questionnaires. Results Mothers with MDR1 3435CT/TT genotype and using medication showed a significant association with the risk of a child with CHD (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.34.3) compared to mothers with MDR1 3435CC genotype not using medication. This risk increased without folic acid use (OR, 2.8; 95% CI, 1.26.4), and decreased in folic acid users (OR, 1.7; 95% CI, 0.83.7). Children carrying the MDR1 3435CT/TT genotype and periconceptionally exposed to medication without folic acid did not show significant risks. Conclusion Mothers carrying the MDR1 3435T allele, using medication without folic acid, are at nearly 3-fold increased risk for CHD in the offspring.