The t(6;11)(q27;q23) translocation in acute leukemia: a laboratory and clinical study of 30 cases. EU Concerted Action 11q23 Workshop participants.

Thirty patients representing 5.5% of those collected by the 11q23 workshop had a t(6;11)(q27;q23). They included 27cases of acute myeloid leukemia (AML) (M1, three cases; M2, two cases; M4, nine cases; M4/M5, one case; M5, 12 cases) of age range 3-72 years and three cases of acute lymphoblastic leukemia (ALL) (B-lineage ALL, two cases; T-ALL, one case) of age range 0.5-13 years. In 20 cases the t(6;11) was the sole abnormality. In 10 cases the recurrent additional abnormalities were extra copies of chromosomes 8, 19, 21, or the der(6). Translocation t(6;11) was identified by cytogenetics alone in 13 cases. In three cases it was confirmed by fluorescence in situ hybridization (FISH) using whole chromosome paints (wcps) 6 and 11. In a further 14 cases involvement of MLL was demonstrated by FISH, by reverse transcriptase polymerase chain reaction (RT-PCR), by Southern blotting (SB) or by a combination of these methods. One case had a direct insertion of 11 into 6-dir ins(6;11)(q27;q13q23). Molecular investigations showed that one case had a 3' deletion of MLL. The median overall survival for the patients was 12 months, indicating a poor prognosis for patients with a t(6;11) translocation.