MAST1 and Ataxia: Congenital hypotonia was accompanied in two-third of patients (n = 28/42; 66.7%); 16/19 patients (84.2%) with ataxia (GNB1, KMT2A, UBE3A, GABRG2, CACNA1A (2), TCF4, ITPR1, FRRS1L, SLC2A1, MAST1, MED13L, DEPDC5, RTEL1, ATM, or EBF3), 6/11 patients (54.5%) with dystonia (TCF4, SLC16A2, KCNQ2, NACC1, CTNNB1, or ARSA), 2/5 patients (40.0%) with stereotypy (ARCN1 or ZEB2), 2/2 patients (100%) with spasticity (GNB1 or DYNC1H1), 1/1 patient (100%) with unspecified dyskinesia (FOXG1), and 1/1 patient (100%) with tremor (FH).