TBX1 and 22q11.2 deletion syndrome: Tbx1 mutant mice are a model of 22q11.2 deletion syndrome (22q11.2DS), a relatively common chromosome microdeletion disorder, for which most of the clinical problems result from TBX1 haploinsufficiency (Yagi et al, 2003; Paylor et al, 2006; Torres-Juan et al, 2007; Ogata et al, 2014).