Genotypes and clinical features of RHO -associated retinitis pigmentosa in a Japanese population

Purpose To report the genotypes and clinical features of RHO -associated retinitis pigmentosa ( RHO -RP) in the Kyushu region of Japan. Study Design Retrospective, single-center study. Methods Sixteen RP patients with pathogenic RHO variants seen at Kyushu University Hospital were investigated. Clinical data including age, best-corrected visual acuity (BCVA) in logarithm of the minimum angle of resolution (logMAR) units, visual field, fundus photography, and optical coherence tomography were retrospectively obtained. Visual outcomes were compared between classical and sector phenotypes and among genetic variants. Results The mean age at the first visit was 54.0 ± 15.7 years, with a mean follow-up of 7.6 ± 4.0 years. Fourteen patients (87.5%) showed the classical RP phenotype, of whom four were associated with p.[Pro23Leu] and two had p.[Pro347Leu] variants. In addition, two patients with the sector phenotype harbored p.[Ala164Val] variants. Among the classical RHO -RP patients, the mean BCVA decreased from 0.60 to 1.08 logMAR over the follow-up period (7.4 ± 4.1 years) whereas BCVA was preserved at 0.04 logMAR in sector RHO -RP patients (9.0 ± 3.0 years). Genotype-to-phenotype analysis demonstrated that p.[Pro347Leu] was associated with severe vision loss at an earlier age. Macular complications such as epiretinal membrane and cystoid macular edema were observed in 5 classical RHO -RP patients. Conclusion p.[Pro23Leu], but not p.[Pro23His], was a frequent variant causing RHO -RP in the Kyushu region of Japan. As reported in previous studies, patients with the p.[Pro347Leu] variant showed a more severe phenotype, and variants causing sector RHO -RP were associated with a good prognosis.