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EPIGenRet : Etude non-interventionnelle, multicentrique, décrivant les patients présentant une Dystrophie Rétinienne Héréditaire (DRH) en France : Analyse intermédiaire

Genetic testing for Inherited Retinal Diseases (IRDs) is fundamental for understanding and treating those diseases. Still, epidemiologic and genetics data on IRD require to be deepen to provide effective care to patients. An innovative public-private collaboration wants to contribute to existing initiatives for IRD data generation by implementing a non-interventional study in France to better understand the epidemiology of IRDs, notably the distribution of pathogenic variants in patients. 

This study is a multicenter, cross-sectional, and non-interventional study conducted on IRD clinically diagnosed patients who attended a consultation in one of the 7 participating sites. The first patient was enrolled into the study on November 30th, 2021, and patients were included consecutively until the threshold of 1000 was reached over a one-year period. To be included into the study, patients must have either available genetic result upon their inclusion in the study (conclusive or not) and/or a genetic testing prescription for IRD. Data are collected from medical records and genetic tests results may be collected until one year after patient inclusion. An interim analysis was performed on all patients included from November 30th, 2021, until May 11th, 2022, to provide first descriptive data on these patients. Outcomes covered by this interim analysis were the type of IRD according to clinical presentation, patients’ socio-demographic and clinical characteristics, and therapeutic care. Genetic outcomes were not assessed in this interim analysis. 

All the 7 participating sites were active, and they enrolled 400 patients into the study from November 30th, 2021 to May 11th, 2022. Of the 400 patients included in the registry, 4 patients did not meet the study eligibility criteria (IRD clinical diagnosis) and were excluded from the analysis, leading to a total of 396 (99.0%) patients. Males (49.7%) and females (50.3%) were equally represented. The mean age (in years) of the analyzable population at inclusion was 41.4 (±19.2), with a vast majority of adults (87.9%). Among patients with information available on age at first symptoms onset (n=287) and at clinical diagnosis (n=283), the mean ages were 20.7 (±18.9) and 27.7 (±18.8) years respectively. Almost all patients (93.2%) presented at least one IRD-related symptom at consultation, with photophobia (61.5%) and night blindness (59.1%) being the most reported among them. Of the analyzable population, 394 patients had an IRD clinical diagnosis recorded. Most of them (78.4%) presented an isolated progressive inherited retinal disorder followed by syndromic rod cone dystrophy (12.9%). The most common forms of IRD recorded were retinitis pigmentosa (ORPHA 791,40.4%), cone-rod dystrophy (ORPHA 1872, 12.7%), Stargardt disease (ORPHA:827, 8.9%) Usher syndrome (ORPHA:886, 5.8%), Bardet-Biedl syndrome (ORPHA:110, 5;6%) and isolated macular dystrophy (ORPHA:519302, 3.6%).

These results provide a first descriptive picture of the IRD profile of patients who attended a consultation in one of the participating centers of this French network. They support the diagnostic odyssey of IRD patients from the onset of symptoms to the moment they are clinically diagnosed. In regards of the type of IRD, retinitis pigmentosa was the most prevalent form of IRDs in the analyzable population, which is consistent with data from existing literature.

These interim data will need to be confirmed by the final results, expected for 2024, to precisely set the characteristics, notably genetics, of the French IRD population.