GPI and Dystonia: Moreover, haplo‐insufficiency of Nkx2.1 in humans, likely leading to subnormal colonization of striatum by PARV+ interneurons, causes dystonia (Breedveld et al., 2002) and recording studies in humans show that, like in dtsz hamsters, GPi neuronal firing is reduced in dystonic individuals (Hashimoto, 2000; Hutchison, Lang, Dostrovsky, & Lozano, 2003; Sanghera et al., 2003; Tang et al., 2007; Vitek et al., 1999; Zhuang, Li, & Hallett, 2004).