Phenotypic heterogeneity in family members of patients with retinitis pigmentosa

PURPOSE: To describe the phenotypic variations in family members of patients with retinitis pigmentosa (RP) with different modes of inheritance and to assess the ocular abnormalities in RP families. METHODS: A descriptive analysis of three types of inheritance of RP was carried out, where 64 family members were examined at a tertiary eye care center, South India. They underwent comprehensive eye examination, fundus photography, fundus autofluorescence (FAF), full-field electroretinogram (FFERG), and spectral domain optical coherence tomography (SD-OCT). Analysis was performed between mild and severe forms of abnormalities to delineate retinal structural and functional defects in RP families. RESULTS: The mean age was 38.55 ± 17.95 years. Males were 48.4%. In autosomal recessive and X-linked recessive groups, 74.2% and 77.3%, respectively, were asymptomatic, whereas in autosomal dominant group, 27.3% were asymptomatic. The proportion of the cases with abnormalities in all three groups was higher on ERG (59.6%), followed by OCT (57.5%), visual acuity (43.7%), peripheral FAF (23.5%), and macular FAF (11.8%). However, these abnormalities and the clinical pictures of the family members had no statistical difference across the three groups of inheritance. CONCLUSION: Structural and functional retinal alterations were noted in four out of five asymptomatic members, suggesting the need for careful screening of RP families and the pressing need for pre-test (genetic) counseling.