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Correlation of cytogenetics, BCR‐ABL PCR studies and fluorescence in situ hybridisation (FISH) in adult acute lymphoblastic leukaemia
Author(s) -
Campbell L. J.,
Martinow A.,
Michael P. M.,
White J. S.,
Rayeroux K. C.,
Januszewicz E. H.
Publication year - 1999
Publication title -
australian and new zealand journal of medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.596
H-Index - 70
eISSN - 1445-5994
pISSN - 0004-8291
DOI - 10.1111/j.1445-5994.1999.tb01619.x
Subject(s) - cytogenetics , chromosomal translocation , fluorescence in situ hybridization , molecular cytogenetics , metaphase , breakpoint cluster region , microbiology and biotechnology , karyotype , philadelphia chromosome , biology , interphase , abl , medicine , chromosome , genetics , tyrosine kinase , gene , signal transduction
Background : Philadelphia positive (Ph+) acute lymphoblastic leukaemia (ALL) accounts for 11–29% of adult ALL. Reverse transcriptase polymerase chain reaction (RT‐PCR) for the BCR‐ABL fusion mRNA has identified patients with the fusion mRNA without cytogenetic evidence of the 9;22 translocation. The reason for discrepancies between cytogenetic and molecular diagnoses is unclear. Aim : Our aim was to study cases of ALL with discordant cytogenetic and RT‐PCR results and identify any reasons for such discrepancies. Methods : Laboratory records were scanned for cases of ALL tested by both RT‐PCR and cytogenetics and positive by either for the 9;22 translocation. Fluorescence in situ hybridisation (FISH) was used to study discordant results where a specimen was available. Results : We identified 15 patients with ALL who had both cytogenetic and RT‐PCR studies for BCR‐ABL. Seven had discordant results; five patients had positive RT‐PCR studies with normal (four/five) or abnormal but Ph negative cytogenetics (one/five), and two were Ph+ but RT‐PCR negative. FISH, using Vysis LSI bcr/abl translocation probes, showed fused signals in 12% interphase cells but not in metaphase cells in one specimen with normal cytogenetics, and 6% interphase cells in the Ph negative patient with abnormal cytogenetics. This second patient subsequently relapsed with a minor Ph+ cell line derived from the Ph negative line. Conclusions : These results confirmed the need for both cytogenetics and RT‐PCR to identify Ph+ ALL. FISH did not show sub‐microscopic rearrangements of BCR‐ABL in normal metaphases. Failure to identify the Philadelphia chromosome cytogenetically appeared due rather to Ph+ cells failing to divide.