Nutrigenetic determinants of neural tube defects in India.

JUSTIFICATION Neural tube defects (NTDs) are one of the commonest birth defects with a high incidence in India. However, few studies have systematically looked into the etio-pathogeneis of NTDs, which mainly includes nutritional deficiencies and genetic predisposition. Efforts are afoot for universal food fortification with folic acid in the hope of preventing NTDs, without factual evidence of folate deficiency in the target population. EVIDENCE ACQUISITION We conducted a review of Indian literature on NTDs focusing on the role of folate and vitamin B12 nutrition and common genetic polymorphisms in 1-carbon metabolism. We performed a literature search of Medline and Indian Medlars (www. indmed.nic.in) for articles using following search terms: Neural tube defect and India, published up to November 2008, on human subjects. We did not include individual case reports and case series describing surgical and medical management, genetic syndromes where NTD was only one of the features or unusual associations of NTDs with other clinical findings. RESULTS Absence of a nationally representative large study, lack of interventional studies and methodological differences were conspicuous during this review. Larger studies are, therefore, urgently needed to delineate genenutrient interactions in association with NTDs in India. We urge that caution should be exercised before widespread folic acid fortification of food, without addressing the issue of concurrent B12 deficiency.