Late‐onset Levodopa Responsive Parkinsonism Due to Polymerase γ 1 Mutations

Introduction: Polymerase γI (POLG) gene mutations may induce mitochondrial DNA (mtDNA) instability leading to its depletion or multiple deletions1 and causing a wide spectrum of multisystemic disorders. Commonly described phenotypes include AlpersHuttenlocher syndrome, childhood myocerebrohepatopathy, myoclonic epilepsy myopathy and sensory ataxia, mitochondrial recessive ataxia syndrome, sensory ataxia neuropathy with dysarthria, and ophthalmoplegia and progressive external ophthalmoplegia (PEO).1 Levodopa-responsive parkinsonism has been described as a late feature in patients with PEO.