Aberrations at the ATM locus have been observed in Chronic Lymphocytic Leukemia (CLL) (11, 12), T-cell prolymphocytic leukemia (T-PLL) (14, 15) diffuse large B-cell lymphoma (DLBCL) (16), mantle cell lymphoma (MCL) (13, 17) and cutaneous T cell lymphoma (CTCL) (18). The gene discussed is ATM; the disease is B-cell chronic lymphocytic leukemia.