Leber Hereditary Optic Neuropathy-Associated Novel Mutation in MT-RNR2 Gene: A Case Report.

Introduction: Leber hereditary optic neuropathy (LHON) is a hereditary optic neuropathy mainly caused by mutations at 1,178, 14,484, and 3,460 in mitochondrial DNA. Patients with LHON have a higher risk of developing multiple sclerosis (MS), a coexistence also known as Harding's syndrome. A growing body of evidence shows that other mitochondrial and non-mitochondrial mutations can lead to LHON and Harding's syndrome. Herein, we report a novel mutation in MT-RNR2 resulting in LHON. Case Presentation: A 35-year-old woman with bilateral painless optic neuropathy presented to neuro-ophthalmology clinic. Her blood work-up did not reveal any nutritional deficiencies, and she did not respond to steroid therapy. Genetic test revealed a m.1737A>G mutation in MT-RNR2 gene with 99.9% penetrance; therefore, she was diagnosed with LHON. Conclusion: MT-RNR2 gene mutation was the possible cause for LHON in this patient. Herein, we describe a novel mutation and associated clinical features. This case report also underscores the importance of considering LHON as a differential diagnosis for optic neuritis, even in a patient with an established MS.