A Mutation ofPCDH15among Ashkenazi Jews with the Type 1 Usher Syndrome

Abstract

The Usher syndrome is an autosomal recessive disorder characterized by bilateral sensorineural deafness and progressive loss of vision due to retinitis pigmentosa. It is the most frequent cause of deafness and concurrent blindness,¹ with a prevalence of 1 in 16,000 to 1 in 50,000.² The majority of cases of the Usher syndrome can be classified into one of three clinical subtypes, the most severe of which is the type 1 Usher syndrome, characterized by profound prelingual hearing loss, vestibular areflexia, and prepubertal onset of retinitis pigmentosa.² Seven loci for the type 1 Usher syndrome (USH1A to USH1G) have been mapped to distinct chromosomal regions by genetic-linkage studies,^2,3 and the causative genes have been identified for five of them.^4-10