Phenotypic and Genotypic Characterization of Patients with Retinitis Pigmentosa in a Tertiary Hospital in the Philippines
Tamilyn Chelsea C. Laddaran, MD, DPBO1, Manuel Benjamin B. Ibanez IV, MD, DPBO1, Marianne Grace P. Navarrete, MD1
1Department of Ophthalmology, Makati Medical Center, Makati, Philippines
Correspondence: Tamilyn Chelsea C. Laddaran, MD, DPBO
Office Address: Department of Ophthalmology, Makati Medical Center, 2 Amorsolo Street, Legaspi Village, Makati City, Philippines
Office Phone Number: +639985377798
Email Address: tamiladdaran@gmail.com
Disclosures: The authors report no conflicts of interest and have no financial disclosures to declare.
ABSTRACT
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.
Keywords: Retinitis pigmentosa, Philippines, genotype, phenotype