P217: Abnormalities of TBX1 Result in Broad Overlapping Features of 22q11.2 Deletion Syndrome

Tbx1 is a member of the Tbox family of binding domain transcription factors. Mice haploinsufficient for Tbx1 have features associated with 22q11.2 deletion syndrome (22q11.2DS). Tbx1-homozygous null mutant mouse embryos die at birth with cleft palate, absent thymus and parathyroid glands, truncus arteriosus and ventricular septal defects. Despite this association with structural anomalies, and more recently autism, clinicians may be unaware of the importance of considering variants in TBX1, located within the 22q11.2 DiGeorge critical region, as a potential etiology to explain findings in individuals with overlapping features of 22q11.2DS but without a deletion.