DNA rearrangements in human B- and T-cell malignancies.

During normal differentiation lymphocytes rearrange immunoglobulin and T-lymphocyte receptor genes. The identification of a rearrangement pattern may serve as a unique clonotypic marker of a lymphoid tumor and can also be used to identify the cellular origin of the neoplasia. The cloning of abnormal breakpoints has resulted in detailed information on the inter-chromosomal translocation process and has also provided probes, which specifically identify abnormal translocations. The use of inter-chromosomal translocation-specific probes in conjunction with immunoglobulin and T-cell receptor gene probes makes it possible not only to prove monoclonality but also to provide strong evidence for neoplasia.