The upper panel shows the comparative mean number of (A) total variants, (B) homoplasmic variants, and (C) heteroplasmic variants stratified by status and tissue origin; where PD = shaded boxes and controls = unshaded boxes. Statistical comparison by Mann-Whitney confirmed a higher heteroplasmic mutational burden in PD patients in both SN and FC (*p = 0.012 and **p = 0.005). The lower panel shows further stratification of heteroplasmic variant burden, limiting to nonsynonomous variants in SN (D) and FC (E) only; where PD = shaded boxes and controls = unshaded boxes. Statistical comparison by Mann-Whitney confirmed a significant (P ≤ 0.0001, starred) overrepresentation of heteroplasmic nonsynonymous variants in PD in MTCOX1, MTCOX2 in SN, and MTCYTB in both SN and FC (error bars indicate 95% confidence intervals). Abbreviations: SN = substantia nigra; FC = frontal cortex; PD, Parkinson's disease; COX, cytochrome c oxidase; ATP, adenosine triphosphate.