Original Contribution The C677T Polymorphism in the Methylenetetrahydrofolate Reductase Gene (MTHFR), Maternal Use of Folic Acid Supplements, and Risk of Isolated Clubfoot: A Case-Parent-Triad Analysis

Worldwide, 1–4 per 1,000 births are affected by clubfoot. Clubfoot etiology is unclear, but both genetic and environmental factors are thought to be involved. Low folate status in pregnant women has been implicated in several congenital malformations, and folate metabolism may be affected by polymorphisms in the methylene-tetrahydrofolate reductase gene (MTHFR). Using a case-parent-triad design, the authors investigated whether the MTHFR C677T polymorphism, and maternal periconceptional folic acid supplement use, influenced risk of isolated clubfoot. Three hundred seventy-five United Kingdom case-parent triads were recruited in 1998–1999. Among the children, there was a significant trend of decreasing clubfoot risk with increasing number of T alleles: relative risk fo