PDCD1 and B-cell chronic lymphocytic leukemia: We observed recurrent methylation changes in additional immune related genes including TCRA, HLA-DQB1, HLA-DQA1, CCR6, HIVEP3, NFATC1, and KLRG1. Using quantitative pyrosequencing in a cohort of CLL CD8+ T-cell samples, we further confirmed the aberrant methylation changes in CCR6 and KLRG1. Interestingly, we found that, similar to PDCD1, DNA hypomethylation of the KLRG1 locus also inversely correlated with mRNA expression within the CD8+ T cells of CLL patients.