TBX1 and 22q11.2 deletion syndrome: Although the TBX1 gene polymorphisms on the residual 22q11 homologous chromatid have not been found to be a major modifier for the pathogenesis of 22q11.2 deletion syndrome in previous studies [33,34], the fact that frequencies of the SNPs rs41298838 and rs41298840 in del22q11.2 CTD patients differed from those in the non-del CTDs patients in this study indicated that polymorphisms of the residual TBX1 gene may have an impact on the pathogenesis of this syndrome.