Distinguishing ABCA4 from PRPH2-related disease: qualitative analysis of examination and imaging features

Introduction: ABCA4 and PRPH2-related diseases are both phenotypically heterogeneous and clinically difficult to differentiate. There may be examination and imaging features that can aid in establishing a clinical diagnosis. Methods: A single-center, retrospective, consecutive case series including patients with a molecular confirmation of pathologic variants in either the ABCA4 or PRPH2 were included. Chi-square analysis, Fisher exact test, and Student’s t-test comparing prevalence of specific examination and imaging features between ABCA4 and PRPH2 Results: Of the 127 eyes from 64 patients included, the ABCA4 group was more significantly associated with peripapillary sparing on both fundus imaging (73% vs. 40%; p = 0.006) and FAF (71% vs. 44%; p = 0.025), macular (64% vs. 12%; p < 0.001) and peripheral pisciform flecks (22% vs. 3.6%; p = 0.025). The PRPH2 group was more highly associated with macular chorioretinal atrophy (86% vs. 55%; p = 0.003). Conclusions: Peripapillary sparing and pisciform flecks are more highly associated with ABCA4-related disease, while macular chorioretinal atrophy is more highly associated with PRPH2-related disease. Logistic regression demonstrates that bull’s eye maculopathy and macular flecks are predictive of the ABCA4 genotype.