Leber Hereditary Optic Neuropathy "Plus" with the m.14487 T>C Mutation as the Causality of Hemidystonia: A Case Report.

Introduction: Leber hereditary optic neuropathy (LHON) complicated with extraocular symptoms is called LHON plus. We describe a case of LHON plus with a rare mutation, which also caused dystonia.

Case presentation: An 18-year-old male patient developed symptoms of dystonia at the age of 15 years. Two years later, he noticed decreased visual acuity and central scotoma in the left eye. One month later, the same symptoms occurred in the right eye. Although the optic discs in both eyes revealed mildly redness and edematous change, no abnormal findings were detected on fluorescence fundus angiography and orbital magnetic resonance imaging. Mitochondrial deoxyribonucleic acid (mtDNA) sequencing detected the m.14487 T>C mutation. From clinical course and fundus findings, the case was diagnosed LHON. The optic nerve gradually atrophied and central scotoma remained.

Conclusion: The m.14487 T>C mutation is one of the causative mutations in patients with dystonia or Leigh encephalopathy and a minor mutation in patients with LHON. However, in the present case, ocular symptoms were more severe than systematic symptoms and the disease course was consistent with LHON. For the above reasons, this case can be diagnosed as LHON plus. Whole mtDNA sequencing is important in diagnosing LHON if none of the three major mutations are detected.