Clin. Lab. Haem. 1997, 19, 33–38 Application of the multi-colour FISH to interphase nuclei and metaphase spreads for simultaneous examination of monosomy 7 and trisomies 8 and 11 in acute myelocytic leukaemia (AML) H. ACAR Department of Medical Genetics, University of Selc ¸uk, A. ACAR Konya, Turkey Summary We have used the multi-colour (three) fluorescence in situ hybridization (FISH) technique based on the ratio labelling for the detection of monosomy 7 and trisomies 8 and 11 in 13 cases of acute myeloid leukaemia (AML). Two out of the 13 AML cases showed monosomy 7 and two out of the remaining cases exhibited trisomy 8 in interphase nuclei. Three of these results were confirmed by metaphase-FISH study. Trisomy 11 was not found either by the interphase FISH study or in the metaphase FISH study. These results demonstrate the potential power of multi-colour FISH using ratio labelling to produce more fluorescein colour in interphase nuclei for the detection of aneuploidies in leukaemia. Keywords Acute myeloid leukaemia, fluorescence in situ hybridization, monosomy 7, trisomy 8 and trisomy 11 Introduction philic lineage, which might therefore be a multi-potential myeloid progenitor cell (Baranger et al. 1990; Kwong et al. Acute myeloid leukaemia (AML) is a malignant disease 1994). This abnormality observed in AML is seen whether which affects immature or undifferentiated myeloid cells alone or as part of a complex karyotype is regarded as and is characterized by their accumulation in bone marrow having a poor prognosis. As for trisomy 11, it is a rare and peripheral blood. Aneuploidy in AML may involve abnormality although it is a consistent finding in AML. monosomy 7 and trisomies 8 and 11(Potter et al. 1992). However, whether alone or with other changes, trisomy Chromosome 8 trisomy is the most frequent and wide- 11 strongly indicates myeloid disease (Potter et al. 1992). spread abnormality in AML, MDS and other human malig- Classical cytogenetic techniques have been extremely nancies (Yunis 1990). This trisomy appears to be relatively valuable in detecting these abnormalities, but insufficient specific for myeloid disorders although it is very rare in metaphases and/or poor chromosome morphology are very lymphoid conditions (Anastasi et al. 1993; Nguyen et al. common problems and leukaemic cells may predominantly 1994). This trisomy is sometimes the sole abnormality or consist of cells in interphase (Heerema et al. 1993). This may occur with other chromosomal abnormalities (Sand- may lead to an underestimation of the size of the malignant berg 1990). Patients with trisomy 8 usually proceed clone if only metaphases are investigated. Recently flu- through a myelodysplastic pre-leukaemic phase before orescence in situ hybridization (FISH) of interphase nuclei developing full-fledged AML (Heim et al. 1987). Lack of and metaphase spreads using chromosome specific DNA specificity suggests a role in disease progression rather than probes has been proposed as an alternative to conventional a causative role. Another frequent change is loss of chro- cytogenetic techniques. By modifying the FISH technique, mosome 7. This abnormality is a marker of an abnormal it has been possible to examine chromosomal abnormalities clone for bone marrow haematopoietic cells. Monosomy 7 with multi-colour (Arnoldus et al. 1990; Lebo et al. 1991). is restricted to myeloid disorders mainly AML, MDS and This system is based on the use of either hapten molecules also in mature eosinophils, but not in lymphoid conditions (Nederlof et al. 1989; Nederlof et al. 1990) or the ratio except in acute Philadelphia (Ph) positive lymphoblastic labelling system (Dauwerse et al. 1992; Reid et al. 1992) leukaemia (ALL). This implies that monosomy 7 occurs in for labelling probes to generate multi-colour FISH. Sim- a progenitor cell common to the granulocytic and eosino- ultaneous detection of multiple chromosomes would have several advantages, such as increased efficiency, smaller Accepted for publication 24 April 1996 sample requirements, and potential for analysis of larger Correspondence: Dr H. Acar, Sakarya Mah. Serbetli Sk 10–4, 42080 33 Konya, Tu ¨ rkiye. numbers of chromosomal abnormalities. © 1997 Blackwell Science Limited