c-myb gene analysis in T-cell malignancies with del(6q).

Three T-cell malignancies with del(6q) were analyzed for karyotypes and alteration of the oncogene c-myb that is assigned to 6q22-q24. Patients were diagnosed as having non-Hodgkin T-cell lymphoblastic lymphoma, adult T-cell leukemia, and acute T-cell lymphoblastic leukemia, and the deletions of chromosome 6 were del(6)(q21q25), del(6)(q21q23), and del(6)(q21) or del(6)(q21q27), respectively. Tumor cell DNAs were obtained from cultured pleural fluid or from fresh peripheral blood and marrow samples and were analyzed by Southern blot hybridization, using c-myb oncogene probes. Rearrangements, deletions, or amplifications were absent in these tumor DNAs, thereby indicating that the del(6q) breakpoint in these T-cell malignancies was located outside of the c-myb gene. Northern blot analysis revealed the elevated expression of c-myb in the non-Hodgkin lymphoma patient, in accord with lineage characteristics.