TBX1 mutations associated with phenocopy of the 22q11.2DS deletion syndrome with cardiac outflow tract defects (DiGeorge syndrome) (craniofacial defects, immune dysfunction, and cardiac defects) with cardiac outflow tract defects, reduced proliferation of second heart field progenitors (SHF), and aortic arch patterning defects [439] (human). Here, TBX1 is linked to immune system disorder.