USH2A and Usher syndrome type 2A: Homozygous or compound-heterozygous mutations in the gene encoding usherin (USH2A) on chromosome 1q41 have been implicated in the pathogenesis of non-syndromic retinitis pigmentosa (RP, OMIM 613809) and in Usher Syndrome Type IIA (OMIM 276901) [4] where RP occurs alongside hearing loss.