Whole exome sequencing reveals novel EYS mutations in Chinese patients with autosomal recessive retinitis pigmentosa

PURPOSE: Retinitis pigmentosa (RP) belongs to a group of inherited retinal diseases with high genetic heterogeneity. This study aimed at identifying the disease-causing variants in patients with autosomal recessive RP. METHODS: Three RP families with autosomal recessive inheritance and 139 sporadic RP patients were included. Complete ophthalmic examinations were conducted in all the study subjects. DNA samples were extracted from patients’ peripheral blood for whole exome sequencing (WES) analysis. Direct Sanger sequencing was conducted for validating the identified mutations and cosegregation pattern in the RP families. RESULTS: One novel (c.7492G>C:p.Ala2498Pro and c.8422C>T:p.Ala2808Thr) and one reported (c.8012T>A:p.Leu2671X and 6416G>A:p.Cys2139Tyr) pair of compound heterozygous mutations, as well as one reported compound homozygous mutation (c.6416G>A:p.Cys2139Tyr/c.8012T>A:p.Leu2671X), were identified in the EYS gene from three families with autosomal recessive RP. All the mutations were cosegregated with the RP phenotype in the RP families. For the sporadic RP patients, seven novel and seven reported EYS variants were identified in 19 patients, including two novel frameshift (c.8301dupT:p.Asp2767fs and c.9437_9440del:p.Glu3146fs), three novel missense (c.8297G>C:p.Gly2766Ala, c.9052T>C:p.Trp3018Arg, and c.8907T>G:p.Cys2969Trp), and one nonsense (c.490C>T:p.Arg164X) variants. All the novel mutations were confirmed by Sanger sequencing. Most of the variants were located at the C-terminus of the EYS protein. Bioinformatics analyses indicated that all detected variants were damaging or possibly damaging. CONCLUSIONS: This study identified eight novel EYS variants and expanded the spectrum of EYS mutations in Chinese RP patients.