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Leber Hereditary Optic Neuropathy: Visual Prognosis and Systemic Associations in Eastern Canada

Guillaume Chabot, Jacinthe Rouleau, Ahmed Zaki Anwar El-Haffaf, Luis Hum Berto Ospina

Leber hereditary optic neuropathy (LHON) is a mitochondrial disease which presents as a bilateral, sequential and painless central loss of vision. Around 90% of the cases are caused by 3 mutations: m.11778G>A (MT-ND4) (52-92% of cases), m.14484T>C (MT-ND6) (3-19% of cases) and m.3460G>A (MT-ND1) (1-33% of cases). Visual recovery is influenced by the mutation type involved. LHON can also be associated with cardiac and neurological manifestations. M.14484T>C (MT-ND6) is found only in 15% to 25% of cases worldwide but is responsible for 86% of all cases of LHON in French Canadian descendants. The goal of this retrospective study is to describe clinical ophthalmic and systemic manifestations, as well as the visual prognosis of LHON patients from Eastern Canada. Patient’s files were reviewed in two Montreal hospitals. We have found 23 patient’s files with a positive mutation for LHON. 87.0% had m.14484T>C (MT-ND6) and 13.0% had m.11778G>A (MT-ND4). No case of m.3460G>A (MT-ND1) was found in our patients. Visual recovery occurred in 23.7% of m.14484T>C (MT-ND6) and in 33.3% of m.11778G>A (MT-ND4). Final visual acuity varied from 20/20 to no light perception. Both cardiac and neurologic abnormalities were found. Our study confirms that m.14484T>C (MT-ND6) is the most prevalent in the province of Quebec, mostly inhabited by French Canadians. It is important to investigate these patients for cardiac and neurologic diseases, as both has been found in our patients.