To determine the nature of deregulated molecular events during PTCL development in Dnmt3aΔ/Δ mice, we performed global methylation analysis using whole genome bisulfite sequencing (WGBS) and gene expression profiling by RNA-seq on CD8+ T cells isolated from Dnmt3a+/+ spleens, as this cellular population is immunophenotypically the closest normal counterpart of CD8+CD4- PTCLs. The gene discussed is CD8A; the disease is mature T-cell and NK-cell non-Hodgkin lymphoma.