Objective: To determine the frequency of known primary mitochondrial DNA (mtDNA) mutations for Leber's hereditary optic neuropathy (LHON) in patients previously diagnosed as having tobacco-alcohol amblyopia.
Design: A case series of 12 patients with tobacco-alcohol amblyopia. Follow-up ranged from 2 months to 15 years.
Setting: Tertiary care.
Patients: Twelve patients diagnosed as having tobacco-alcohol amblyopia, based on the classic clinical presentation, were tested for all the known primary mtDNA mutations associated with LHON. All patients had a history of heavy alcohol or tobacco use or both. Twelve other patients who fit inclusion criteria were unable to be contacted or refused to participate in the study.
Main outcome measures: Presence of a known primary mutation for LHON at nucleotide positions 11778, 3460, 15257, or 14484 of mtDNA.
Results: Two (17%) of 12 patients previously diagnosed as having tobacco-alcohol amblyopia tested positive for known LHON genetic mutations, one for the 11778 mutation and one for the 3460 mutation.
Conclusions: The diagnosis of LHON should be considered in all patients diagnosed as having tobacco-alcohol amblyopia, particularly those with visual acuities of 20/200 or less. The availability of molecular genetic testing for LHON now allows confirmation of the diagnosis of LHON in patients who otherwise may be misdiagnosed.