USH2A and retinitis pigmentosa 1: The causative genes were determined in the previous genomic sequence analysis of 83 RP causative genes37 as follows: eye shut homolog in 10 patients (20.1%), usherin in 3 patients (6.3%), pre-mRNA processing factor 8 in 2 patients (4.2%), retinitis pigmentosa 1 in 1 patient (2.1%), rhodopsin in 1 patient (2.1%), retinitis pigmentosa 1-like 1 in 1 patient (2.1%), and retinitis pigmentosa GTPase regulator in 1 patient (2.1%), and the causative genes were not determined in 29 patients (60.4%).