To better understand the molecular changes occurring in Dnmt3a-deficient mice we performed global methylation profiling using whole genome bisulfite sequencing (WGBS) and gene expression profiling using RNA-seq on CLL and PTCL tumors isolated from Dnmt3aΔ/Δ mice, as well as control B-1a and CD8+ T cells. The gene discussed is CD8A; the disease is B-cell chronic lymphocytic leukemia.