A hospital-based five-year prospective study on the prevalence of Leber’s hereditary optic neuropathy with genetic confirmation

PURPOSE: To estimate the prevalence of Leber hereditary optic neuropathy (LHON) along with genetic screening at a tertiary eye care center in southern India. METHODS: Patients with LHON were identified at the Neuro-Ophthalmology Clinic, Aravind Eye Hospital (AEH; Madurai, India) from 2015 to 2019. Clinical data were collected along with blood samples. Genetic testing was performed for the confirmation of LHON using a multiplex PCR restriction fragment length polymorphism (RFLP) approach to detect the primary mutations 3460A, 11778A, and 14484C in mitochondrial DNA (mtDNA). RESULTS: During the study period, 1,598,441 outpatients attended AEH of whom 40,527 were referred to the Neuro-Ophthalmology Clinic. Among them, 55 patients were diagnosed with LHON. The male to female ratio was 8.2:1.0, and the mean age at onset was 20.95 years (SD 8.940). The estimated prevalence was 1:737 or 13.57 per 10,000 (95% confidence intervals [CI] 10.23–17.66) at the Neuro-Ophthalmology Clinic. The frequency of primary mutations in the patients with LHON was determined as 43.6% (24/55), giving a prevalence of 1:1689 or 5.92 per 10,000 (95% CI 3.78–8.81). CONCLUSIONS: The high prevalence of LHON observed at a single hospital highlights the impact of the disease in southern India. As the epidemiology of LHON remains unexplored in this region, these findings will pave the way to evaluate the national prevalence. Further, screening the whole mitochondrial genome may help to increase the detection of mutations to estimate the accurate prevalence of the disease.