MACROH2A1 and Alzheimer disease: The nature of this sex-dependent phenomenon may be epigenetic, as we previously showed that compared to WT males, 3×Tg-AD males show increased expression of macroH2A1 (formerly H2afy) [61], which codes for macroH2A1, a variant of the canonical histone H2A, important in neuroplasticity [23, 102] and often upregulated during neurodegenerative processes [33, 47, 52]).