Several apoptosis-associated genes, including TNFRSF25 (tumor necrosis factor receptor superfamily member 25), were found to be methylated in HMC-1.2 cells (established from a patient with mast cell leukemia) but not in normal bone marrow leukocytes, suggesting that these genes are aberrantly hypermethylated in blood neoplasia [23]. The gene discussed is TNFRSF25; the disease is mast cell leukemia.