The noncortical origin of the myoclonus is supported electrophysiologically in 5 genetic disorders presenting with M‐D (MYC/DYT‐SGCE, MYC/DYT‐KCTD17, DYT‐ANO3, ATX‐ATM, ATX‐PRKCG) and unknown in 2 others (CHOR/DYT‐ADCY5 and CHOR‐NKX2‐1). The gene discussed is ATM; the disease is hereditary disease.