For those patients with ataxia syndromes (i.e., 2 patients with a nuclear POLG mutation and 3 patients with a nuclear SPG7 mutation), this trend was most striking for signal changes in the cerebellum, where a higher voxel fraction with aberrant [11C]PK11195 binding was associated with worse performance on the SARA scale (figure 6, C, F, and G; figure e-3 available from Dryad: doi.org/10.5061/dryad.zs7h44j7s). The gene discussed is SPG7; the disease is cerebellar ataxia.