Characterizing the Genetic Basis for Inherited Retinal Disease: Lessons Learned From the Foundation Fighting Blindness Clinical Consortium's Gene Poll

The Foundation Fighting Blindness (FFB) Consortium is a collaboration of 41 international clinical centers that manage patients affected with inherited retinal diseases (IRDs). The annual Consortium gene poll was initiated in 2020 to capture the genetic cause of disease in patients with IRD and associated clinical practices of Consortium sites. Data from the 2022 gene poll are reported here. In 2022, academic, private practice, and government ophthalmology clinics that are members of the Consortium centers were polled to identify per-case IRD genetic causality from a list of 387 syndromic and nonsyndromic IRD genes. The survey also assessed how genetic testing was obtained and clinical practices of the sites. Thirty centers responded and reported genetic data from 33,834 patients (27,561 families). Disease-causing variants were reported in 293 of 387 genes. The most common genetic etiologies were ABCA4 (17%), USH2A (9%), RPGR (6%), PRPH2 (5%), and RHO (4%). The top 100 genes accounted for the genetic cause of disease in 94.4% of patients. Two-thirds of the centers had at least one genetic counselor. In the 21 US sites, genetic testing was commonly obtained through sponsored programs (95%, FFB-My Retina Tracker Programs or Spark-ID Your IRD), whereas in the 9 non-US sites, genetic testing was commonly obtained using either patient- or public health system-funded testing pipelines. Clinical work-up of patients with IRD most commonly included updating history, eye examination, and optical coherence tomography. This report provides the largest assessment of genetic causality in the IRD patient population across multiple continents to date.