2 UNBALANCED TRANSLOCATIONS, T(12-22)(P13-Q11) AND T(12-QUESTIONABLE)(P13-QUESTIONABLE), IN AN AGGRESSIVE CHRONIC B-CELL LEUKEMIA - TEL GENE ANALYSIS USING FISH

The translocation t(12;22)(p13;q11) has been consistently described in myeloid malignancies and shown to result from a fusion between the TE L and MN1 genes. Previously described deletions of 12p in acute lympho blastic leukemias have been recently shown to harbor undetected transl ocations involving the TEL gene at 12p13. We document a case of an agg ressive chronic B-cell leukemia whose cells had trisomy 12 and two unb alanced translocations involving 12p13, including a t(12;22)(p13;q11) as shown by conventional cytogenetics and fluorescence in situ hybridi zation (FISH). The 12p13 breakpoint of the t(12;22)(p13;q11) was telom eric to the TEL gene, and the second unbalanced translocation with bre akpoint 12p13 resulted in the deletion of TEL. This case demonstrates that TEL gene deletions may be relevant in cases of mature B-lymphopro liferative diseases. (C) Elsevier Science Inc., 1997.