Article

Case Report

Korean J Lab Med 2010; 30(6): 711-717

Published online December 1, 2010 https://doi.org/10.3343/kjlm.2010.30.6.711

Copyright © Korean Society for Laboratory Medicine.

Variant Philadelphia Chromosome Identified by Interphase Fluorescence In Situ Hybridization (FISH) without Evidence on G-banded Karyotyping and Metaphase FISH

Mi Kyung Kim, M.D.1, Yeung Chul Mun, M.D.2, Chu Myong Seong, M.D.2, Wha Soon Chung, M.D.1, and Jungwon Huh, M.D.1

Departments of Laboratory Medicine1 and Internal Medicine2, Ewha Womans University School of Medicine, Seoul, Korea

Correspondence to: Jungwon Huh, M.D.
Department of Laboratory Medicine, Ewha Womans University Mokdong Hospital, 911-1 Mok-dong, Yangcheon-gu, Seoul 158-710, Korea
Tel : +82-2-2650-5287, Fax : +82-2-2650-5091
E-mail : JungWonH@ewha.ac.kr

Received: April 29, 2010; Revised: July 14, 2010; Accepted: September 19, 2010

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A variant Philadelphia chromosome (Ph) is generated from translocation of one or more partner chromosomes in addition to chromosomes 9 and 22. We have described the cases of 2 patients bearing variant Ph detected by interphase FISH but not detected by G-banded karyotyping and metaphase FISH. FISH was performed using BCR/ABL dual color dual fusion translocation probes (Abbott Molecular, USA). A 52-year-old man was diagnosed with acute leukemia of mixed phenotype. G-banded karyotyping showed 46,XY,t(9;22)(q34;q11.2)[12]/47,idem,+der(22)t(9;22)[5]/46,XY[3]. Interphase FISH revealed nuc ish(ABL1,BCR)×3(ABL1 con BCR×2)[329/450]/(ABL1,BCR)× 4(ABL1 con BCR×3)[5/450]/(AL1,BCR)×3(ABL1 con BCR×1)[44/450]. Metaphase FISH showed ish (9;22)(ABL1+,BCR1+;BCR+,ABL+)[22]/der(22)(BCR+,ABL1+)[3]. The other case was that of a 31-yr-old male patient diagnosed with CML in the blastic phase. G-banded karyotyping of all 20 metaphase cells showed 47,XYYc,dup(1)(q21q32),del(7)(p11.2),t(9;22)(q34;q11.2). Interphase FISH revealed nuc ish(ABL1,BCR)×3(ABL1 con BCR×2)[254/600]/(ABL1,BCR)×3(ABL1 con BCR×1)[191/600]. Metaphase FISH showed ish t(9;22)(ABL1+,BCR+;BCR+,ABL1+)[16]. These results suggest that typical t(9;22) and variant Ph may coexist in the same patient, and interphase FISH may facilitate the detection of the variant Ph that cannot be detected by G-banded karyotyping alone.

Keywords: Philadelphia chromosome, Variant, FISH, Interphase, Metaphase