1. ¹Department of Hematological Biology, Institute Paoli Calmettes, Marseille, France
2. ²Laboratory of Immuno-hematology, Department of Hematology, Aarhus University Hospital, Aarhus, Denmark
3. ³Department of Immunology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
4. ⁴Applied Biosystems, Foster City, CA, USA
5. ⁵Department of Experimental Immunohematology, CLB, Amsterdam, The Netherlands
6. ⁶Department of Hematology, Necker Hospital, Paris, France
7. ⁷Department of Clinical and Biological Science, University of Turin, Ospedale San Luigi Gonzaga, Orbassano-Torino, Italy
8. ⁸Children's Cancer Research Institute, St Anna Children's Hospital, Vienna, Austria

Correspondence: Professor J Gabert, Department of Biochemistry and Molecular Biology Laboratory, IFR Jean Roche, Faculté de Médecine Nord, Bd Pierre Dramard, 13916 Marseille Cedex 20, France. Fax: +33 491 69 87 51; E-mail: gabert.j@jean-roche.univ-mrs.fr

⁹JG is a consultant for Ipsogen

¹⁰First co-authors

¹¹Current address: Department of Biochemistry & Molecular Biology, Hôpital Universitaire Nord, ERT MEiDiA IFR Jean Roche, Université de la Méditerranée, Marseille, France

Received 16 October 2002; Accepted 17 June 2003; Published online 9 October 2003.

Abstract

Real-time quantitative RT-PCR (RQ-PCR) is a sensitive tool to monitor minimal residual disease (MRD) in leukemic patients through the amplification of a fusion gene (FG) transcript. In order to correct variations in RNA quality and quantity and to calculate the sensitivity of each measurement, a control gene (CG) transcript should be amplified in parallel to the FG transcript. To identify suitable CGs, a study group within the Europe Against Cancer (EAC) program initially focused on 14 potential CGs using a standardized RQ-PCR protocol. Based on the absence of pseudogenes and the level and stability of the CG expression, three genes were finally selected: Abelson (ABL), beta-2-microglobulin (B2M), and beta-glucuronidase (GUS). A multicenter prospective study on normal (n=126) and diagnostic leukemic (n=184) samples processed the same day has established reference values for the CG expression. A multicenter retrospective study on over 250 acute and chronic leukemia samples obtained at diagnosis and with an identified FG transcript confirmed that the three CGs had a stable expression in the different types of samples. However, only ABL gene transcript expression did not differ significantly between normal and leukemic samples at diagnosis. We therefore propose to use the ABL gene as CG for RQ-PCR-based diagnosis and MRD detection in leukemic patients. Overall, these data are not only eligible for quantification of fusion gene transcripts, but also for the quantification of aberrantly expressed genes.