Because HDACs are also expressed in PBMCs (Zhang et al., 2011) and these peripheral cells were previously shown by us to be affected in early AD human and mouse stages, correlating with changes in cerebral cortex (Mota et al., 2015), we determined the levels of HDAC2 and HDAC3 in PBMCs derived from MCI subjects (Clinical Dementia Rating (CDR) of 0.5, as described in Mota et al., 2015) or AD patients with increasing degrees of cognitive impairment. The gene discussed is HDAC2; the disease is Alzheimer disease.