Shortstop mice do not manifest the neuronal dysfunction or degeneration of the YAC128 model. (A) Shortstop do not exhibit a deficit on an accelerating rotarod, whereas YAC128 mice demonstrate a deficit compared with WT littermates (P < 0.001). (B-D) The shortstop mice at 12 months do not exhibit significant brain weight decrease (B), striatal volume decrease (C), or striatal neuronal count decrease (D) when compared with WT mice, whereas YAC128 mice demonstrate significant decreases. (E and F) At 18 months, there is no significant decrease in brain weight (E) or striatal volume (F) of shortstop mice compared with WT mice; YAC128 mice exhibit significant deficits. Mean ± SD is shown in B-F, and mean ± SEM is shown in A. Data were analyzed by a one-way ANOVA, and P values between groups were calculated by using Tukey's posttest.