This reminiscent of the phenotypes with a high incidence of lumbar spina bifida in the mouse model crossed of un mutant and Patch (Ph) mutant mice (Helwig et al., 1995) which is a deletion of the gene encoding the platelet-derived growth factor receptor alpha subunit (PDGFRα) (Stephenson et al., 1991), suggesting the possibility of an involvement of PAX1 in the occurrence of NTD. Here, PAX1 is linked to spina bifida.