Thyroid adenomas belong to the cytogenetically best investigated human epithelial tumors. Cytogenetic studies of about 450 benign lesions allow one to distinguish between different cytogenetic subgroups. Two chromosomal regions, that is, 19q13 and 2p21, are frequently rearranged in these tumors. Although 2p21 aberrations only account for about 10% of the benign thyroid tumors with clonal cytogenetic deviations, 2p21 rearrangements belong to the most common cytogenetic rearrangements in epithelial tumors due to the high frequency of these benign lesions. The 2p21 breakpoint region recently has been delineated to a region of 450 kbp, but the gene affected by the cytogenetic rearrangements still has escaped detection. Positional cloning and 3' RACE-PCR allowed us to clone that gene which we will refer to as thyroid adenoma associated (THADA) gene. In cells from two thyroid adenomas characterized by translocations t(2;20;3) (p21;q11.2;p25) and t(2;7)(p21;p15), respectively, we performed 3'-RACE-PCRs and found two fusions of THADA with a sequence derived from chromosome band 3p25 or with a sequence derived from chromosome band 7p15. The THADA gene spans roughly 365 kbp and, based on preliminary results, encodes a death receptor-interacting protein.