Bosley-Salih-Alorainy syndrome (BSAS) is an autosomal recessive disorder characterised by bilateral Duane retraction syndrome, profound sensorineural deafness and, in some cases, external ear defects. A spectrum of other symptoms may be present including delayed motor development, vascular malformations of the internal carotid arteries and cardiac outflow tract, mental retardation and autism spectrum disorder, facial weakness, seizures, and minor facial and limb abnormalities.  BSAS is caused by disease-causing variants in the HOXA1 gene (Tischfield et al. 2005 Nat Genet 37:1035-7). In BSAS patients with homozygous HOXA1 variants, 88% (14/16) had bilateral Duane retraction syndrome, 81% (13/16) had bilateral deafness, 63% (10/16) had delayed motor development and 31% (5/16) had cardiovascular malformations (Bosley et al. 2008 Am J Med Genet 146A:1235-1240).

BSAS has a phenotypic overlap with Athabaskan Brainstem Dysgenesis syndrome (ABDS) which is also caused by homozygous HOXA1 variants. ABDS is characterised by horizontal gaze restriction, deafness, mental retardation, facial and bulbar weakness, central hypoventilation, cardiac malformations and cerebral vascular malformations (Tischfield et al. 2005 Nat Genet 37:1035-7).   


The laboratory participates in the European Molecular Genetics Quality Network (EMQN) sequencing scheme.