Standardization criteria for the detection of BCR/ABL fusion in interphasenuclei of chronic myelogenous leukemia patients by fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH), as a new clinical test, is not p resently standardized. For practical reasons, each laboratory must build it s own criteria. In this work, we present our standardization criteria for c linical practice, which include not only the methods for cell fixation, spe cimen preparation, and hybridization conditions, but mainly the definition of false-positive range and the scoring criteria of microscopic analysis. T hese include signal assessment, difference between individual microscopists , evaluation of specimen homogeneity, and the minimum number of scored nucl ei required for a clinically reliable result. For this purpose, we analyzed by FISH 24 healthy volunteer donors, 31 patients affected by non-chronic m yelogenous leukemia (CML) hematological malignancies, 47 CML patients at di agnosis, and 82 CML patients during treatment for the BCR/ABL fusion. In th is article, we present several quality control and assurance methods that c an be useful in providing standardization of the FISH technique. (C) 2000 E lsevier Science Inc. All rights reserved.