title: Comparison of FISH and quantitative RT-PCR for the diagnosis and follow-up of BCR-ABL-positive leukemias.
abstract: BACKGROUND
  For Philadelphia chromosome positive (Ph+) leukemias (chronic myelogenous leukemia [CML], acute lymphoblastic leukemia [ALL], and rare other leukemias), both allogeneic transplantation and treatment with tyrosine kinase inhibitors offer chances of molecular remission (the molecular marker being consistently undetectable). Molecular remission is defined as a reduction in the quantification of BCR-ABL transcripts to an undetectable level by molecular diagnostic methods, and is considered as a surrogate marker for cure or long-term disease control. The molecular diagnostic methods including fluorescence in situ hybridization (FISH) and quantitative reverse transcription-polymerase chain reaction (QRT-PCR) are more sensitive than classical cytogenetic analysis for the detection of BCR-ABL positive cells. QRT-PCR, due to its superior sensitivity, is considered the gold standard for the follow-up of Ph+ leukemias treated with imatinib.
  
  
  OBJECTIVE
  The objective of our study was to compare the diagnostic and clinical usefulness of FISH and QRT-PCR at different timepoints for Ph+ leukemias.
  
  
  METHODS
  We investigated 23 unselected patients with Ph+ CML (n = 21) or Ph+ ALL (n = 2) at 77 different timepoints in a comparative study with both FISH and QRT-PCR using commercially available reagents in a routine laboratory.
  
  
  RESULTS
  Our study demonstrated a good correlation of QRT-PCR with FISH in detecting the BCR-ABL fusion gene among patients with CML or ALL (coefficient of correlation = 0.77493, p < 0.0001, using Spearman's correlation procedure). All newly diagnosed or untreated cases were positive with both methods. Lower coefficients of correlation were found when FISH and QRT-PCR were correlated with the white blood cell count (WBC). An overall concordance of FISH and QRT-PCR (being either negative or positive in both tests) was found in 65 cases (84.4%) and a discrepancy identified in 12 cases (15.6%).
  
  
  CONCLUSIONS
  We confirm that QRT-PCR allows precise measurement of low levels of BCR-ABL transcripts and can serve as a sensitive indicator for minimal residual disease. In addition, we demonstrate in most cases a good correlation of QRT-PCR with FISH in detecting the BCR-ABL fusion gene among patients with CML or Ph+ ALL. FISH is not suitable for monitoring minimal residual disease.
authors: Department of Pathology, Louisiana State University, Shreveport, Louisiana, USA.
authors: Fei
authors: F
authors: Bao
authors: Reinhold
authors: R
authors: Munker
authors: Clarissa
authors: C
authors: Lowery
authors: Sherry
authors: S
authors: Martin
authors: Runhua
authors: R
authors: Shi
authors: Diana M
authors: DM
authors: Veillon
authors: James D
authors: JD
authors: Cotelingam
authors: Mary Lowery
authors: ML
authors: Nordberg
mesh_terms: D000328:Adult; D000368:Aged; D001772:Blood Cell Count; D005260:Female; D005500:Follow-Up Studies; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007938:Leukemia / Q000097:blood / Q000175:diagnosis* / Q000378:metabolism*; D007962:Leukocytes; D008297:Male; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*
chemical_list: D016044:Fusion Proteins, bcr-abl
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