Objective: To describe clinical molecular testing for hereditary retinal degenerations, highlighting results, interpretation, and patient education.
Methods: Mutation analysis of 8 retinal genes was performed by dideoxy sequencing. Pretest and posttest genetic counseling was offered to patients. The laboratory report listed results and provided individualized interpretation.
Results: A total of 350 tests were performed. The molecular basis of disease was determined in 133 of 266 diagnostic tests; the disease-causing mutations were not identified in the remaining 133 diagnostic tests. Predictive and carrier tests were requested for 9 and 75 nonsymptomatic patients with known familial mutations, respectively.
Conclusions: Molecular testing can confirm a clinical diagnosis, identify carrier status, and confirm or rule out the presence of a familial mutation in nonsymptomatic at-risk relatives. Because causative mutations cannot be identified in all patients with retinal diseases, it is essential that patients are counseled before testing regarding the benefits and limitations of this emerging diagnostic tool.
Clinical relevance: The molecular definition of the genetic basis of disease provides a unique adjunct to the clinical care of patients with hereditary retinal degenerations.