HDAC9 and Alzheimer disease: In a previously reported coexpression network study in AD and control brains, HDAC9 and MEF2C were clustered together in the top fourth module ranked by relevance to AD pathology, and expression of HDAC9 and MEF2C was inversely correlated with Braak stage (HDAC9, r = −0.71; MEF2C, r = −0.65) and frontal atrophy (HDAC9, r = −0.57, MEF2C, r = −0.51) [18].