RP1 and retinitis pigmentosa: To screen for possible disease-causing mutations in rhodopsin (RHO), pre-mRNA processing factor 31 (PRPF31), retinitis pigmentosa 1 (RP1), and inosine monophosphate dehydrogenase 1 (IMPDH1) genes in Indian patients with isolated and autosomal dominant forms of retinitis pigmentosa (adRP).