The lineage involvement in myelodysplastic syndromes (MDS) is still unclear. To 
determine the clonality and the evolution of the disorder, a retrospective study 
on bone marrow smears from seven MDS patients with trisomy 8 was performed using 
fluorescence in situ hybridization (FISH). We observed that the trisomy of 
chromosome 8 was selectively expressed in the myeloid-derived cells. No mature 
lymphocytes or plasma cells expressed three signals. Our studies demonstrate 
here the value of FISH for identifying the affected cell lineage. Furthermore, 
the easy quantification of the abnormal cells can help in assessing the 
progression of the disease.