PRDM9 and Alzheimer disease: These results indicate that upregulation of H3K4 HMT results in the elevated level of H3K4me3 in patients with AD and in P301S tau mice.187 Repressive mark H3K9me2 and histone methyltransferases EHMT1 and EHMT2 were significantly elevated in the late-stage familial AD mouse model and in patients with AD.