HPCA and Dystonia: KCTD17 mRNA was shown to be broadly expressed across the brain but particularly in the putamen, consistent with dystonia being caused by dysfunction of basal ganglia circuits.79 Fibroblasts derived from a KCTD17 patient (p.Arg145His) exhibit defective ER calcium signaling, which is suggested to underlie myoclonus‐dystonia linked to mutations in other genes (e.g., HPCA, CACNA1A, ANO3).79, 83