Ocular albinism late onset sensorineural deafness (OASD) is a rare, X-linked recessive disease characterized by intense visual impairments, reduced retinal pigments, translucent pale-blue irises and moderately severe hearing loss from adolescence to middle-age.[1] It is a subtype of Ocular Albinism (OA) that is linked to Ocular albinism type I (OA1). OA1 is the most common form of ocular albinism, affecting at least 1/60,000 males.
OA has two patterns of inheritance: X-linked and autosomal. X-linked OA includes OA1 (Nettleship-Falls type), OA2 (Forsius-Eriksson type) and OASD. Autosomal inheritance, on the other hand, includes OCA3 (autosomal recessive OA) and OA with sensorineural deafness.[2] As OA1 is X-linked, males are generally more affected than females. The cause of OASD is believed to involve mutations of the GPR143 gene, which is responsible for pigment proteins production and melanosome growth control. This gene is located on the X-chromosome at Xp22.3, which is also where TBL1 gene is found. The physical proximity of the two genes suggest that OASD and OA1 result from contiguous-gene syndrome.
There are three main diagnostic methods: molecular genetic tests, family pedigree analysis and antenatal diagnosis. While there is no definite treatment for OASD, annual ophthalmologic examinations are suggested for preventative measures.