Instability of the Ph Chromosome in Chronic Myelocytic Leukemia: A Case Report

Abstract

Chronic myelocytic leukemia (CML) is a clonal myeloproliferative disorder characterized cytogenetically by the Philadelphia (Ph) chromosome, which arises from a reciprocal translocation, (9;22)(q34;q11), and is characterized molecularly by the fusion of parts of the C-ABL gene (9q34) with parts of the BCR gene (22q11), generating an abnormal BCR/ABL fusion gene [ 1 Rowley J.D. A new consistent chromosomal abnormality in chronic myelogenous leukemia identified by quinacrine fluorescence and Giemsa staining. Nature. 1973; 243: 290-292 Crossref PubMed Scopus (3339) Google Scholar , 2 de Klein A. Hagemeijer A. Cytogenetic and molecular analysis of the Ph translocation in chronic myeloid leukemia. Cancer Surv. 1984; 3: 515-529 Google Scholar ]. In general, more than 85% of patients diagnosed as having CML are found to have the Ph chromosome [ 3 Sandberg A.A. The Chromosomes in Human Cancer and Leukemia. ed 2. Elsevier Science, New York1990 Google Scholar ]. Variant forms of Ph translocations are seen in 5–10% of CML cases [ 3 Sandberg A.A. The Chromosomes in Human Cancer and Leukemia. ed 2. Elsevier Science, New York1990 Google Scholar ]. When CML progresses, additional chromosome aberrations are noted in 75–80% of the cases, the most common ones being trisomy 8, an additional Ph, an i(17q), trisomy 19, trisomy 21, and loss of a sex chromosome [ 3 Sandberg A.A. The Chromosomes in Human Cancer and Leukemia. ed 2. Elsevier Science, New York1990 Google Scholar ].