Clinical and genetic characterization of BEST1 ‐associated retinal dystrophies in the Norwegian population

Purpose BEST1 variants are the third leading cause of inherited retinal dystrophies in Norway. The purpose of this study was to describe the BEST1‐associated retinal dystrophy (BEST1‐RD) population genetically and clinically, and to determine the prevalence of BEST1‐RD in Southern and Eastern Norway. Methods This registry‐based study used the Oslo University Hospital Inherited Retinal Disease registry for genetic data and extracted clinical data from medical records. Results Sixty patients were included. The prevalence of BEST1‐RD in Southern and Eastern Norway was between 1:64 600 and 1:43 700. Forty‐one patients were diagnosed with Best's vitelliform macular dystrophy (BVMD), 15 with autosomal recessive bestrophinopathy (ARB) and 4 with autosomal dominant vitreoretinochoroidopathy (ADVIRC). The two most common genotypes were c.403G>A and c.89A>G. These variants were associated with BVMD and a later age of onset compared with other BVMD‐associated genotypes. Conclusion The prevalence of BEST1‐RD in Southern and Eastern Norway was between 1:64 600 and 1:43 700. BVMD patients carrying c.403G>A or c.89A>G had a later age of onset than BVMD patients carrying other variants.