TAC1 and acute lymphoblastic leukemia: Another 6 (TAC1, HMX2, HLA-G, VSNL1, PAX7, PAX9) genes demonstrated frequent methylation in leukemia cell lines but were also frequently methylated in DNA from healthy bone marrow and a further 2 genes showed cancer specific methylation from analysis of leukemia cell lines and healthy bone marrow and blood DNA but showed either no or very low frequency of methylation in primary ALL samples (TNFAIP1, TLR2).