TOR1A and early-onset generalized limb-onset dystonia: While many genetic animal models of DYT1 dystonia have been reported [13], the Dyt1 ΔGAG heterozygous knock-in (KI) mouse is an ideal genetic mouse model for DYT1 dystonia with the ΔGAG mutation because it expresses the mutant allele from the endogenous promoter [14, 15].