Phenotypic and Genotypic Characterization of Patients with Retinitis Pigmentosa in a Tertiary Hospital in the Philippines

Objectives: To determine the phenotypic and genotypic characterization of individuals with retinitis pigmentosa (RP), identify their genetic etiologies, and provide counseling to affected patients. Methods: This non-interventional, observational study evaluated 18 patients with clinically-diagnosed RP from 15 different families. The patients underwent complete ophthalmological examination with retinal functional and morphologic assessment. Genetic testing was done using next-generation sequencing. Results: Ten gene mutations with 22 variants were identified. The inheritance pattern was predominantly autosomal recessive (70%). The most common mutation was EYS (27.8%). One possible novel gene, RGS7, and novel variants of CNGB1 were identified. Characteristic RP profiles were observed, with syndromic findings noted in USH2A and BBS5 mutations. Conclusion: Phenotypic characteristics among different gene mutations have distinct features. This is the first study in the country to demonstrate the genotypic heterogeneity of RP, displaying 22 variants with 3 noted novel mutations.