Spina bifida and anencephaly. Geographic correlation with the HLA system.

The geographical correlation between the incidence of spina bifida and anencephaly and the HLA and ABO antigen frequencies are studied. There is a positive correlation between these malformations and A1 and B8, and a negative correlation with B5 and Bw35. The role of the HLA system itself, or of a human T-like locus, is discussed. This study provides evidence of a possible genetic background of susceptibility to these malformations.