TH and mitochondrial DNA depletion syndrome 7 (hepatocerebral type): In a mouse model expressing mutant Twinkle, there was accelerated accumulation of mtDNA deletions and loss of TH-positive neurons (leading to motor impairment).10 Patients with biallelic C10orf2 mutations typically present with severe and complex neurologic phenotypes (e.g., infantile-onset spinocerebellar ataxia, epilepsy, sensory polyneuropathy, Perrault syndrome, and adult-onset mitochondrial myopathy) alongside systemic features, but not parkinsonism.