A founder mutation in CERKL is a major cause of retinal dystrophy in Finland

Purpose To study the genetic aetiology of retinal dystrophies ( RD ) in Finnish patients. Methods A targeted next‐generation sequencing (NGS) panel of 105 retinal dystrophy genes was used in a cohort of 55 RD patients. Results The overall diagnostic yield was 60% demonstrating the power of this approach. Interestingly, a missense mutation c.375C>G p.(Cys125Trp) in the CERKL gene was found in 18% of the patients in either a homozygous or compound heterozygous state. Data from Exome Aggregation Consortium (ExAC) Browser show that the CERKL c.375C>G p.(Cys125Trp) allele is enriched in the Finnish population and thus is a founder mutation. Furthermore, we report the clinical picture of 18 patients with mutations in the CERKL gene. CERKL mutations cause a macular‐onset disease, in which symptoms first become apparent at the second decade. We also detected other novel founder mutations in the CERKL , EYS , RP 1 , ABCA 4 and GUCY 2D genes. Conclusion Our report indicates that the first diagnostic test for Finnish patients with sporadic or autosomal recessive RD should be a targeted test for founder mutations in the CERKL , EYS , RP 1, ABCA 4 and GUCY 2D genes. These results confirm the utility of NGS ‐based gene panels as a powerful method for mutation identification in RD , thus enabling improved genetic counselling for these families.