SBS84 localized mutational activity and AID involvement was also observed across known AID off-target genes, similar to what has been reported in human MM, and implicated in the mutations affecting the driver genes: Dusp2, Pim1, H1f4/Hist1h1e, and H1f2/Hist1h1c (Supplementary Fig. 10). Here, H1-4 is linked to Miyoshi myopathy.