A small proportion of NTDs in live born infants are associated with specific syndromes that are associated with chromosomal or single-gene disorders . NTDs are currently considered as “complex” disorders with genetic and environmental factors playing roles in causation , which have been summarized in Table 1. Craniorachischisis and encephalocoele have the highest rate of syndromic association, anencephaly and high spina bifida have intermediate rates, and caudal spina bifida has the lowest rate . The role of folic acid in preventing syndromic NTDs turned out to be not as gratifying as for nonsyndromic (isolated), multifactorial NTDs . It should be noted that while syndromic NTDs may have identifiable genetic causes, many of the nonsyndromic (isolated) NTDs have unidentified genetic etiology. Most of human neural tube defects are nonsyndromic with NTD being the only defect. The focus of this review paper is on nonsyndromic (isolated) spina bifida apart from the clearly stated syndromic spina bifida mentioned specifically in Table 1.