Thus the data presented here are derived from individuals with compound heterozygous and homozygous pathogenic USH2A mutations (n = 18), individuals with only one identified USH2A mutant allele (n = 18), as well as individuals with clinically diagnosed Usher syndrome type 2 in which no genotype has been determined (n = 29). This evidence concerns the gene USH2A and Usher syndrome type 2.