ARCN1 and Myoclonus: Epilepsy was present in almost half of patients (n = 18/42; 42.9%); 7/17 patients (41.2%) with ataxia (CACNA1A (2), UBE3A, GABRG2, FRRS1L, MED13L, or DEPDC5), 5/11 patients (45.5%) with dystonia (PIGA, KCNQ2, NACC1,WASHC5, or ARSA), 2/5 patients (40.0%) with stereotypy (DHDDS or ARCN1), 2/3 patients (50.0%) with myoclonus (TUBB2B or DHDDS), 1/1 patient (100.0%) with unspecified dyskinesia (FOXG1), and 1/1 patient (100.0%) with tremor (FH).