Consistent with the MBD-seq data, pyrosequencing data also showed hypomethylation of the TET1 promoter in both CLL and normal B cells, whereas hypermethylation of TET1 gene-body in all CLL samples (n=40; median 55.7%) compared to normal B cell samples (n=5; median 25%) (Figure 1B). The gene discussed is TET1; the disease is B-cell chronic lymphocytic leukemia.