Genotypes & molecular strategies in albinism

Abstract

AbstractOculocutaneous albinism (OCA) affects 1/17000 person. It is characterized by hypopigmentation of the skin, hair and eyes. The main handicap in patients is at the ophthalmologic level. There are 6 known OCA genes (TYR, OCA2, TYRP1, SLC45A2, SLC24A5, C10ORF11) (OCA1,2,3,4,6,7 respectively). An OCA5 locus has been localized, but the gene is not known yet. Apart from the OCA types, an X‐linked ocular albinism gene (OA1, GPR143) as well as 17 genes involved in syndromic forms (HPS, CHS, WS, GS) of albinism have been identified. We routinely search for mutations (point mutations, deletions) in the OCA1, 2, 3, 4, 6 ,7, OA1 and HPS1 genes. Our data in more than 400 patients show 36% OCA1, 25% OCA2, 2% OCA3, 11% OCA4, 1.25% OCA6, 0% OCA7, 6% OA1, 1% HPS1. 17.75% of patients remain without a molecular diagnostic either because only one mutation (6%)or no mutation at all (11.75%) was found. This suggests two main alternative hypotheses. First of all the patient may have a hitherto clinically undiagnosed form of syndromic albinism. For this reason, we are now heading towards analyzing all 24 known albinism genes by next generation sequencing. Secondly, it is likely that additional OCA genes remain to be identified.