The function of PHF13 (PHD finger protein 13, Ensembl gene identifier ENSG00000116273) is as follows. Modulates chromatin structure and DNA damage response by regulating key determinants of chromatin compaction and DNA damage response (PubMed:19638409). Binds H3K4me3-containing chromatin and promotes DNA condensation by recruiting corepressors such as TRIM28 and H3K9 methyltransferase SETDB1 (PubMed:23034801). Required for normal chromosome condensation during the early stages of mitosis. Required for normal chromosome separation during mitosis (PubMed:19638409). Increases both chromatin-associated levels and activity of H3K9 methyltransferases, such as SETDB1, thus enhancing H3K9 trimethylation (PubMed:23034801). Essential for testicular stem-cell differentiation and sustained spermatogenesis (By similarity). {ECO:0000250|UniProtKB:Q8K2W6, ECO:0000269|PubMed:19638409, ECO:0000269|PubMed:23034801}.