Loss of heterozygosity and heterogeneity of its appearance and persisting in the course of acute myeloid leukemia and myelodysplastic syndromes

Screening for loss of heterozygosity (LOH) of the panel of 18 highly polymo rphic microsatellite markers, especially from the region 11p15, was carried out on 154 samples from 26 patients with acute myeloid leukemia and eight with myelodysplastic syndromes (MDS). LOH was detected at the majority (72% ) of the loci tested: 47% of informative patients displayed LOH for at leas t one of the microsatellite locus from the region 11p15 and 23.5% of patien ts displayed LOH among the other markers tested within the study. A longitu dinal follow-up of patients showed a remarkable heterogeneity of LOH appear ance and its persistance during the course of the disease suggesting an int ratumor clonal heterogeneity, or alternatively, presence of LOH in more tha n one cell clone. The data revealed two regions of high loss of one allele in 11p15.5, defined by markers D11S1363 and D11S1338, indicating that LOH a t the subtelomeric region of the short arm of chromosome 11 is a much commo n event in hematological malignancies than it was previously reported. (C) 2001 Elsevier Science Ltd. All rights reserved.