BAZ1B and Williams syndrome: Studying rare events that result in atypical deletions sparing different genes in the Williams syndrome critical region (WSCR), as well as single gene knock out studies in mouse models, have suggested that GTF2IRD1 and BAZ1B play a role in the craniofacial abnormalities (Ashe et al., 2008; Tassabehji et al., 2005).