AbstractBACKGROUNDNeural tube defects (NTDs) are complex embryological malformations, affecting 1 in 1,000 live births. Antisense studies have implicated murine Mab21 genes as having an important role in neural tube development. We investigated whether MAB21L1/L2 genes could be involved in the aetiology of NTDs.METHODSDenaturing HPLC (DHPLC) analysis of MAB21 genes was performed in 116 NTD cases. A case‐control approach was used to test if the two single nucleotide polymorphisms (SNPs) of the MAB21L1 gene might be associated with increased NTD risk.RESULTSNo pathological variants of MAB21L1/L2 genes were identified by DHPLC analysis. Case‐control studies demonstrated that the two SNPs (CAG triplets in 5′UTR; A→C in 3′UTR) in the MAB21L1 gene are unlikely to be directly responsible for myelomeningocele.CONCLUSIONSWe suggest that MAB21 genes are unlikely to have substantial impact on NTDs. These preliminary findings will need to be investigated in larger samples before firm conclusions can be made. Birth Defects Research (Part A), 2004. © 2004 Wiley‐Liss, Inc.