Provided herein are compositions and methods related to the production and detection of a histone H1.0 protein dimethylated at lysine residue 180 (K180) (H1.0K180me2 protein) or a histone H1.0 peptide dimethylated at a lysine residue corresponding to K180 (H1.0K180me2 peptides). The H1.0K180me2 protein and H1.0K180me2 peptides are useful for applications including, but not limited to, molecular diagnostics of DNA damage, genotoxic stress, radiation exposure, and Alzheimer's disease, therapeutics, monitoring of therapeutic regimens, patient stratification, and drug screening. Also provided herein are antibodies specific for the H1.0K180me2 protein and H1.0K180me2 peptides.