HOXA1 and ventricular septal defect 1: Studies in humans found severe cardiovascular anomalies including tetralogy of Fallot, ventricular septal defect and BAV in patients carrying a homozygous truncating mutation in HOXA1 [Bosley-Salih-Alorainy (BSAS)32; Athabascan Brainstem Dysgenesis Syndrome (ABDS)33].