title: Clonal evolution in atypical chronic granulocytic leukemia: a non-Philadelphia translocation.
abstract: Hemopoietic cells in chronic granulocytic leukemia (CGL) frequently contain a chromosome translocation involving chromosome 22 and another autosome, usually number 9. The translocated chromosome 22 is known as the Philadelphia (Ph) chromosome. The appearance of a second Ph chromosome is the most common cytogenetic abnormality in CGL signaling the blastic phase. For 6 yr we serially studied a man with atypical CGL whose marrow cells were marked by a translocation from chromosome 18 to chromosome 11 [46XY,t(11;18)(q23;q12)]. Three months prior to blast transformation there appeared an extra copy of the marker chromosome 18: 47XY,t(11;18)(q23;q12),+(18p11 leads to 18q12). This man presents a new cytogenetic pattern of clonal evolution in CGL. The pattern is analogous to that of the Ph chromosome and is characterized by a balanced chromosomal rearrangement and the subsequent acquisition of an extra copy of the small translocation chromosome immediately prior to blast transformation.
mesh_terms: D000328:Adult; D001854:Bone Marrow Cells; D002471:Cell Transformation, Neoplastic; D002904:Chromosomes, Human, 21-22 and Y; D002999:Clone Cells; D006801:Humans; D007621:Karyotyping; D007951:Leukemia, Myeloid / Q000235:genetics*; D008297:Male; D014178:Translocation, Genetic