HDAC9 and Huntington disease: In our meta-analysis, HDCA2 (Z-ratios: 0.69, 1.84, 1.86) and HDAC9 (Z-ratios: 2.26, 0.88, 1.42) were upregulated in the brain of HD patients, while the histone deacetylase 5 (HDAC5) mRNA levels were decreased (Z-ratios: -0.18; -2.17; -2.02).