The histone methyltransferase DOT1L induces H3K79me3 at the Jag1 promoter to upregulate Notch ligand Jagged1 and hyperactivate Notch signalling to promote fibroblast activation and collagen deposition in a BLM-induced PF model (Yang D. et al., 2022). The gene discussed is JAG1; the disease is pemphigus foliaceus.