The highly conserved transcription factor tbx1 is required to maintain the SHF progenitor pool,49,50 and loss of TBX1 results in 22q11.2 deletion syndrome (DiGeorge syndrome).51tbx1 mutant zebrafish have been shown to have a shorter OFT,29,38,49 but the impact on the arterial valve remains uninvestigated. Here, TBX1 is linked to 22q11.2 deletion syndrome.