 In peripheral blood of at least 50% of healthy individuals, the translocations t(9;22) BCR/ABL, t(14;18) IgH/BCL-2, t(2;5) NPM-ALK and MLL duplications, which characterize chronic myelogenous leukemia and acute lymphoblastic leukemia, follicular lymphoma, anaplastic large cell lymphoma, and acute myelogenous leukemia, respectively, are detectable by sensitive polymerase chain reaction (PCR). 