Huntington’s disease mice had significantly lower levels of Htr1a mRNA than WT mice in the striatum [Figure 2A; F(1,70) = 23.938, p < 0.001], hippocampus [Figure 2B; F(1,72) = 73.098, p < 0.001], and cortex [Figure 2C; F(1,71) = 39.875, p < 0.001]. This evidence concerns the gene HTR1A and juvenile Huntington disease.