Retinitis pigmentosa: mutation analysis of RHO, PRPF31, RP1, and IMPDH1 genes in patients from India

PURPOSE 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). Information on such data is not available in India and hence this study was undertaken. METHODS Blood samples were obtained from 48 isolated and 53 adRP patients, who were recruited for the study. Each patient underwent a detailed clinical examination. Genomic DNA was extracted from the blood samples and screened for mutations in four genes using an ABI3100 Avant genetic analyzer. Reverse transcriptase polymerase chain reaction was performed to amplify the mutated (IVS6+1G/A) mRNA of PRPF31 in a two-generation adRP family. RESULTS Of the 101 probands analyzed, three harbored possible disease-causing mutations. Pathogenic changes were observed in RHO and PRPF31. A RHO mutation, p.Gly106Arg, was found in an isolated RP patient with sectoral RP. Two novel, heterozygous mutations were identified in PRPF31: p.Lys120GlufsX122 in an isolated RP patient and a splice site mutation, IVS6+1G/A in an adRP patient. However, no disease-causing changes were observed in RP1 and IMPDH1. CONCLUSIONS We screened RHO, PRPF31, RP1, and IMPDH1 and identified causative mutations in 4% of isolated and 2% of adRP patients from India. To the best of our knowledge, this is the first report to identify frequencies of mutations in isolated and adRP patients in India.