The thymic lymphomas from the VN mice and VKD mice are both clonal, immature (TCRβ/CD3low) (Figure 2—figure supplement 1D–E) with frequent trisomy 15, have focal amplifications around the TCRα/δ loci, and have hemizygous deletion of the telomeric portion of chromosome 12, as is the case for previously characterized Atm-/- thymic lymphomas (Jiang et al., 2015b; Zha et al., 2010) (Figure 2—figure supplement 2A). This evidence concerns the gene ATM and thymus lymphoma.