A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Summary: The human HOXA1 mutation syndromes commonly present with abnormalities of the inner ear and internal carotid arteries. Previous cases describe varying degrees of hypoplasia or aplasia of the affected structures, often with asymmetrical involvement. We present imaging findings documenting complete absence of the internal carotid arteries bilaterally with bilateral Michel aplasia of the inner ear, which, to our knowledge, has not been previously reported. Based on the number of cases identified and birth rates within studied populations, we estimated the incidence of ABDS at 0.5-1:1000 live births on the White River Apache Reservation and 1:3000 live births in the Navajo population. If accurate, this suggests a carrier frequency similar to that for cystic fibrosis in Caucasian populations. ABDS may represent a significantly underrecognized disorder among Athabaskan Native Americans, raising questions of the possible benefit of genetic counseling for affected families. However, cultural considerations in this population bring into question the possible conflict between counseling based on gene theory and traditional beliefs.