Inherited retinal disease in Norway - a characterization of current clinical and genetic knowledge

The purpose of this study was to characterize current clinical and genetic knowledge of patients with inherited retinal disease in Norway and give an estimate of the prevalence. These data are necessary to identify patients eligible for new personalized medicines, to facilitate genetic counselling for their families and to plan clinical follow-up.

A patient registry including clinical and genetic data was established. Clinical data were retrieved during 2003-2018. Genetic testing was performed in the period 2007-2018.

The material included 866 patients with 41 clinical diagnoses at the cut-off date. The most prevalent diseases were as follows: retinitis pigmentosa (54%), Stargardt macular dystrophy (6.5%) and Leber congenital amaurosis (5.2%). A genetic diagnosis was identified in 32% of patients. In total, 207 disease-causing variants in 56 genes were reported. The most commonly reported disease-causing genes were ABCA4, USH2A and BEST1. The estimated adjusted minimum prevalence of inherited retinal disease in the south-east region of Norway was 1: 3,856 (2.6/10 000).

This population-based study demonstrated an estimated prevalence for all inherited retinal diseases in south-east Norway and described the distribution of clinical diagnoses, onset of symptoms, inheritance patterns and genetic data and thereby expands our knowledge of inherited retinal disease in Norway. The newly established registry and biobank will support patient feasibility for future clinical trials, treatment selection and counselling of families.