Dicentric (7;9)(p11;p11) is a rare but recurrent abnormality in acute lymphoblastic leukemia: a study of 7 cases.

A clinical and experimental study of acute lymphoblastic leukemia (ALL) with a dic(7;9)(p11;p11) included 7 patients (5 males and 2 females) with a median age of 32 years. Cytogenetic analysis of bone marrow cells using an R-band technique showed a solitary dic(7;9) in 2 cases and a dic(7;9) accompanied by other abnormalities in 5 cases, of which 4 had also a t(9;22)(q34;q11). A minor breakpoint region (m-bcr) BCR/ABL rearrangement, corresponding to the fusion product gene p190, was detected by interphase FISH in 3 of these cases, Immunophenotyping analysis classified five of the 6 cases as B-lineage ALL. In 6 cases, FISH using whole chromosome painting (WCP) probes for chromosome 7 and 9 confirmed the reciprocal translocation between chromosomes 7 and 9; centromeric probes for chromosomes 7 and 9 confirmed the dicentric nature of the abnormal chromosome. The outcome of these ALL cases with simultaneous dic(7;9) and t(9;22) was worse than that of cases with an isolated dic(7;9). Our study brings the total number of published ALL cases with a dic(7;9) to 18. We consider the dic(7;9) a rare but recurrent abnormality, which may represent a distinct cytogenetic subgroup in B-ALL.