I thought neural tube defects were caused by a deficiency in Folic acid so why do some papers talk about molecular mutations?
Multiple alleles at multiple gene loci plus environmental factors are involved in neural tube defects. NTDs are what geneticists call a discontinuous, mutifactorial trait (in contrast, height is a continuous trait). You either have a NTD or you do not. It is thought that inheritance of a certain number of risky alleles and exposure to enough adverse environmental factors crosses a threshold beyond which normal development cannot occur. Clinical research into NTD and congenital heart disease is currently concentrating on methionine and homocysteine metabolism. ( http://www3.ncbi.nlm.nih.gov/htbin-post/Omim/dispmim?601634 ) It may be that the problem is not a simple deficiency of folic acid, it is thought that an “overdose” of folic acid can normalize methionine and homocysteine metabolism in the population who are at risk of NTD. Mutations in cystathionine beta synthase, methionine synthase and methyl tetra hydrofolate reductase have been associated with neural tube defects, cleft lip a
