Phenotypic heterogeneity of the mitochondrial DNA A8344G variant presenting with dorsal midbrain syndrome

PURPOSE: To describe a neuro-ophthalmic presentation of a phenotypically heterogeneous mitochondrial DNA variant. OBSERVATIONS: A 10-year-old female with gross motor developmental delay, absence seizures and ataxia subacutely developed poor near acuity and asthenopia. She was found to have accommodative insufficiency, impaired supraduction and convergence retraction nystagmus leading to a diagnosis of dorsal midbrain syndrome. Brain MRI showed highly symmetrical lesions involving the dorsal pons. Genetic testing revealed a previously undiagnosed mitochondrial DNA (mtDNA) pathogenic variant, adenine to guanine at nucleopeptide pair 8344 (A8344G). CONCLUSION AND IMPORTANCE: The authors describe a unique, neuro-ophthalmic manifestation of mitochondrial disease in a pediatric patient. This report discusses the phenotypic heterogeneity of the mtDNA A8344G variant, which may include ‘stroke-like episodes’ involving the brainstem, thus presenting with ophthalmic manifestations.