Deletions of the derivative chromosome 9 occur at the time of the Philadelphia translocation and provide a powerful and independent prognostic indicator in chronic myeloid leukemia

• Published in: Blood Vol. 98; no. 6; pp. 1732 - 1738
• Main Authors: Huntly, Brian J.P., Reid, Alistair G., Bench, Anthony J., Campbell, Lynda J., Telford, Nick, Shepherd, Patricia, Szer, Jeff, Prince, H. Miles, Turner, Paul, Grace, Colin, Nacheva, Elizabeth P., Green, Anthony R.
• Format: Journal Article
• Language: English
• Published: Washington, DC Elsevier Inc 15-09-2001; The Americain Society of Hematology
• Subjects: Adult; Biological and medical sciences; Chromosome Deletion; Chromosomes, Human, Pair 9 - ultrastructure; Female; Hematologic and hematopoietic diseases; Humans; In Situ Hybridization, Fluorescence; Leukemia, Myelogenous, Chronic, BCR-ABL Positive - diagnosis; Leukemia, Myelogenous, Chronic, BCR-ABL Positive - genetics; Leukemia, Myelogenous, Chronic, BCR-ABL Positive - mortality; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Male; Medical sciences; Middle Aged; Philadelphia Chromosome; Prognosis; Survival Rate; Chromosomal aberration; Human; Prognosis; Malignant hemopathy; Philadelphia chromosome; Myeloproliferative syndrome; Abnormal chromosome C9; Chronic; Chronic myelocytic leukemia; Abnormal chromosome G22; Cytogenetics; Deletion; Abnormal chromosome; Genetics; Chromosome translocation
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V98.6.1732

Chronic myeloid leukemia (CML) is characterized by formation of theBCR-ABL fusion gene, usually as a consequence of the Philadelphia (Ph) translocation between chromosomes 9 and 22. Large deletions on the derivative chromosome 9 have recently been reported, but it was unclear whether deletions arose during disease progression or at the time of the Ph translocation. Fluorescence in situ hybridization (FISH) analysis was used to assess the deletion status of 253 patients with CML. The strength of deletion status as a prognostic indicator was then compared to the Sokal and Hasford scoring systems. The frequency of deletions was similar at diagnosis and after disease progression but was significantly increased in patients with variant Ph translocations. In patients with a deletion, all Ph+metaphases carried the deletion. The median survival of patients with and without deletions was 38 months and 88 months, respectively (P = .0001). By contrast the survival difference between Sokal or Hasford high-risk and non–high-risk patients was of only borderline significance (P = .057 andP = .034). The results indicate that deletions occur at the time of the Ph translocation. An apparently simple reciprocal translocation may therefore result in considerable genetic heterogeneity ab initio, a concept that is likely to apply to other malignancies associated with translocations. Deletion status is also a powerful and independent prognostic factor for patients with CML. The prognostic significance of deletion status should now be studied prospectively and, if confirmed, should be incorporated into management decisions and the analysis of clinical trials.