Chronic myeloid leukemia with variant chromosome translocations: A series of eleven cases. Indian Journal of Human Genetics. Accepted.
The Philadelphia (Ph) chromosome, consisting of the t(9;22)(q34;q11) translocation, is observed in ~90% of patients with chronic myeloid leukemia (CML). 5%-%–10% of CML patients show variant Ph translocations. Variant translocations can be defined as involvement of 3 three and possibly more chromosomes. Herein we report 11 CML patients with variant Ph translocations. Bone marrow samples were studied using conventional and molecular cytogenetic techniques. Fluorescence in situ hybridization (FISH) was used to confirm and/or complement the findings, and identify complex rearrangements beyond conventional cytogenetics resolution. All the patients were under treatment with different inhibitors of tyrosine kinase. Among all the patients, 6 six were showing simple and 5 five were complex Ph translocations. Three types of hybridization patterns were seen through FISH. A number of studies have reported that some patients with variant Ph translocation were weak responders to imatinib. All of our patients with variant Ph translocation had suboptimal responses to imatinib or other drugs, indicating poor prognosis. Variant Ph translocation may be important as they are associated with poor prognosis and response to therapy in CML patients.