Department of Human Genetics, Radboud University Nijmegen Medical Centre, 6525 GA Nijmegen, The Netherlands; Institute for Genetic and Metabolic Disease, 6525 GA Nijmegen, The Netherlands.
Molecular diagnostics for patients with retinitis pigmentosa (RP) has been hampered by extreme genetic and clinical heterogeneity, with 52 causative genes known to date. Here, we developed a comprehensive next generation sequencing approach (NGS) for the clinical molecular diagnostics of RP. All known inherited retinal disease genes (n=111) were captured and simultaneously analyzed using NGS in 100 RP patients without a molecular diagnosis. A systematic data analysis pipeline was developed and validated to prioritize and predict the pathogenicity of all genetic variants identified in each patient, which enabled us to reduce the number of potential pathogenic variants from ∼1,200 to 0-9 per patient. Subsequent segregation analysis and in silico predictions of pathogenicity resulted in a molecular diagnosis in 36 RP patients, comprising 27 recessive, 6 dominant and 3 X-linked cases. Intriguingly, de novo mutations were present in at least 3 out of 28 isolated cases with causative mutations. This study demonstrates the enormous potential and clinical utility of NGS in molecular diagnosis of genetically heterogeneous diseases such as RP. De novo dominant mutations appear to play a significant role in patients with isolated RP, having major implications for genetic counselling.