der(9) deletion
About 95% of the CML patients with chronic myeloid leukemia (CML) have a Philadelphia chromosome resulting from a reciprocal translocation between bands 9q34 and 22q11.2 that juxtaposes the 3’ region of the ABL gene to the 5’ region of BCR.
Over the past few years, submicroscopic deletions due to the loss of sequences proximal to chromosome 9 breakpoint or distal to chromosome 22 breakpoint have been found using fluorescence in situ hybridization (FISH).
Der(9) deletions are seen in 10-15% of CML patients. The deletion size of the 5’ABL region on the der(9) extended from 2 to 5 Mb. The deletion size of the 3’BCR region was about 500 kb.
Der(9) have been associated with a poor prognosis. The poor prognosis associated with these deletions was postulated by several workers to be explained by haploinsufficiency of a tumor suppressor gene.
References
Kreil S, Pfirrmann M, Haferlach C, Waghorn K, Chase A, Hehlmann R, Reiter A, Hochhaus A, Cross NC. Heterogeneous prognostic impact of derivative chromosome 9 deletions in chronic myelogenous leukemia. Blood. 2007 Apr 24; PMID: 17456720
Douet-Guilbert N, Morel F, Quemener S, Maguer A, Le Bris MJ, Morice P, Berthou C, De Braekeleer M. Deletion size characterization of der(9) deletions in Philadelphia-positive chronic myeloid leukemia. Cancer Genet Cytogenet. 2006 Oct 15;170(2):89-92. PMID: 17011977
Calabrese G, Fantasia D, Di Gianfilippo R, Stuppia L, Di Lorenzo R, Palka G. Fluorescence in situ hybridization analysis of minimal residual disease and the relevance of the der(9) deletion in imatinib-treated patients with chronic myeloid leukemia. Haematologica. 2006 Jul;91(7):994-5. PMID: 16818290
Fourouclas N, Campbell PJ, Bench AJ, Swanton S, Baxter EJ, Huntly BJ, Green AR. Size matters: the prognostic implications of large and small deletions of the derivative 9 chromosome in chronic myeloid leukemia. Haematologica. 2006 Jul;91(7):952-5. PMID: 16818283
Xinh PT, Vu HA, Nghia H, Binh NT, Van Be T, Van Binh T, Tokunaga K, Sato Y. Coexistence of Philadelphia chromosome positive cells with and without der(9) deletion in a patient with chronic myelogenous leukemia. Cancer Genet Cytogenet. 2006 Jan 15;164(2):122-7. PMID: 16434314