The linking of iSPN dysfunction, as reflected in reductions in both ENK and apparently DARPP32, to increased turning is of interest, as hyperkinesia is predicted for iSPN loss/hypofunction in the indirect–direct pathway model of basal ganglia function (Albin et al., 1989; DeLong, 1990; Reiner et al., 1988). The gene discussed is PPP1R1B; the disease is Hyperkinetic movements.