Parents

Mutations in HOXA1 gene can cause two diseases with similar/overlapping clinical manifestations, namely Athabascan brainstem dysgenesis syndrome (ABDS) and Bosley-Salih-Alorainy syndrome (BSAS). There are caused by mutations in both the copies of HOXA1 gene, and hence it is passed on to the next generation in autosomal recessive mode. This suggests that there is 25% chance for the offspring to inherit this disease if their parents are carriers (a person who has one copy of a mutated disease-causing gene but has no symptoms or mild symptoms) of this disease. Multiple organ systems can be affected in patients with these diseases, which can lead to ocular motility disorder (eye movement disorder), sensorineural deafness (a type of hearing loss), cerebrovascular malformations (vascular malformations related to the blood vessels that supply the brain and other cranial structures), CHD (structural heart defects) and motor developmental delay (related to problems with gross movement skills, such as crawling). The patients of ABDS can be distinguished from BSAS with the presence of central hypoventilation (a disorder that affects normal breathing) and intellectual disability. Additionally, congenital heart disease and weakness of facial muscles can also be variably present in patients with ABDS. ABDS has been described only in two Native American tribes (Navajo and Apache), whereas the majority of the patients with BSAS have been reported from Saudi Arabia, except four (two from India, one from Turkey, and one suspected possible BSAS phenotype patient of Navajo descent) patients from different geographical regions.