Derivative chromosome 9 deletions are a significant feature of childhood Philadelphia chromosome positive acute lymphoblastic leukaemia

Robinson, H.M., Martineau, M., Harris, R.L., Barber, K.E., Jalali, G.R., Moorman, A.V., Strefford, J.C., Broadfield, Z.J., Cheung, K.L. and Harrison, C.J. (2005) Derivative chromosome 9 deletions are a significant feature of childhood Philadelphia chromosome positive acute lymphoblastic leukaemia. Leukemia, 19 (4), 564-571. (doi:10.1038/sj.leu.2403629).

Abstract

Deletions from the derivative chromosome 9, der(9), of the translocation, t(9;22)(q34;q11), at the site of the ABL/BCR fusion gene, have been demonstrated by fluorescence in situ hybridisation (FISH), in both Philadelphia chromosome (Ph)-positive chronic myeloid leukaemia (CML) and acute lymphoblastic leukaemia (ALL). In CML they occur in 10?15% of cases and appear to indicate a worse prognosis, whereas in ALL, the situation is unclear. This study presents the findings of dual fusion FISH used to detect such deletions in a series of 27 BCR/ABL-positive childhood ALL patients. Metaphase FISH was essential for the accurate interpretation of interphase FISH signal patterns. Three cases (11%) had a single fusion signal, resulting from deletions of the der(9). Three other patients with variant translocations and one with an insertion, also had a single fusion, but with no evidence of deletions. Gain of a fusion in approximately one-third of patients indicated a second Ph, which appears to be a diagnostic marker of Ph-positive ALL. This study shows that the incidence of deletions from the der(9) in childhood ALL is at least as high as that reported for CML.

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Contributors

Author: J.C. Strefford

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