HOXA1 and human HOXA1 syndromes: Finally, abnormal development of the VIth nerve occurs in two conditions in which mutations of the gene HOXA1 (located at 7p15 and implicated in hindbrain segmentation during fetal development) are responsible: the Bosley-Salih-Alorainy syndrome (BSAS) and the Athabascan Brainstem Dysgenesis syndrome (ABDS).