Expanding the clinical and genetic spectrum of RHO-associated retinitis pigmentosa

The majority of cases of autosomal-dominant retinitis pigmentosa (adRP) are associated with rhodopsin (RHO) variants. More than 290 pathogenic variants responsible for 25%–30% of adRP cases have been identified to date. This retrospective report focuses on RHO and RP cases in the Brazilian population. Patients with molecular confirmation of pathogenic variants in the RHO gene were included. Their clinical and genetic data were analyzed. Segregation analyses were included where possible. Cases were classified as generalized RP or sector RP according to fundus examinations and imaging data. The medical records of 43 patients from 34 families with RHO -associated RP were reviewed. Twenty-two disease-causing variants of the RHO gene and four previously unreported variants (c.317G>T; c.937-2A>T, c.272_283del, and c.530+1G>C) were identified. The majority of cases involved missense variants. The most prevalent variant was c.551A>G, p.(Gln184Arg), which was identified in seven patients (21%) from four families. One patient presented with the splice donor variant c.530+1G>C in the homozygous state, which was classified as pathogenic. Thirty-two patients presented with a generalized RP phenotype, and six patients were diagnosed with sector RP. This study provides information on the clinical and genetic features of RHO -associated RP in the Brazilian population, expanding the spectrum of RHO gene disease-causing variant frequencies.