Congenital stationary night blindness (CSNB) is a rare and typically nonprogressive group of genetically heterogeneous disorders resulting in impaired night vision and high myopia with varying levels of visual impairment. Despite being a rare disease with a prevalence of 1:294,000, variants in 22 genes have been associated with specific CSNB phenotypes. Approximately, 13% of cases remain without a genetic diagnosis, highlighting the importance of ongoing genetic studies. Clinical and diagnostic information was collected retrospectively from patients who were diagnosed with CSNB. Patients underwent full ophthalmic examination, including best-corrected visual acuity (BCVA), direct and indirect ophthalmoscopy, retinal imaging, and full field electroretinography. All patients underwent panel-based genetic testing for complete and incomplete CSNB genes to identify DNA variants from buccal swab samples. In the 49-patient cohort (from 38 families) with complete and incomplete CSNB, a conclusive molecular diagnosis was found in 30 patients (61.2%) with a known disease-causing variant in a CSNB gene. We identified 21 novel variants in five genes (CACNA1F, NYX, TRPM1, GPR197, and GRK1), and in one patient, the genetic defect remains to be identified. After in silico modeling and clinical correlation, 18 of these novel variants were considered pathogenic or likely pathogenic. When compared with ethnicity, CSNB was overwhelmingly present in White people, and we did not find any Indigenous people with CSNB. Prevalence of CSNB in the Mennonite community was estimated to be 1:967, approximately 300 times the expected prevalence. Establishing a molecular diagnosis of CSNB is critical because it enables many actionable outcomes including further family testing, genetic counseling, and access to future clinical trials.
Copyright © 2026 Jennifer Ling et al. Human Mutation published by John Wiley & Sons Ltd.