title: Philadelphia chromosome duplication as a ring-shaped chromosome.
abstract: The gain of a second copy of the Philadelphia chromosome is one of the main secondary chromosomal changes related to the clonal evolution of cells with t(9;22) in chronic myelogenous leukemia. This gain causes the acquisition of another copy of theBCR/ABL1fusion gene. Isochromosomes of the der(22) chromosome or double minute chromosomes are well known to lead an increased copy number ofBCR/ABL1gene. There is no antecedent of Philadelphia chromosome duplication as a ring chromosome. A recent published report contains evidence that strongly suggests that the Philadelphia chromosome was duplicated as a ring chromosome, observation that was overlooked by the authors. The instability inherent to the ring chromosome increases the risk of emergence of clones containing more and moreBCR/ABL1gene copies, which would produce increased fitness for clonal selection, resulting in worsening of the patient's prognosis.
authors.affiliation: Division de Genetica. Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social, Sierra Mojada # 800. Colonia Independencia, CP 44340 Guadalajara, Jalisco Mexico ; Doctorado en Genetica Humana, CUCS-Universidad de Guadalajara, Guadalajara, Jalisco Mexico.
authors.forename: Cesar
authors.initials: C
authors.lastname: Borjas-Gutierrez
authors.affiliation: Division de Genetica. Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social, Sierra Mojada # 800. Colonia Independencia, CP 44340 Guadalajara, Jalisco Mexico.
authors.forename: Juan Ramon
authors.initials: JR
authors.lastname: Gonzalez-Garcia
keywords: Duplication; Philadelphia chromosome; Ring chromosome; Secondary chromosomal changes; der(22) chromosome; t(9;22) translocation