HDAC9 was significantly downregulated in subjects with AD compared with control subjects in several brain regions, including the TCX (P = 1.5 × 10−4) and CER (P = 0.04) in the RNA-Seq profiling data and in the DLPFC (P = 7.9 × 10−3) and VCX (P = 5.6 × 10−4) in the microarray expression data. The gene discussed is HDAC9; the disease is Alzheimer disease.