Loss of heterozygosity in acute leukemia: evidence of frequent submicroscopic deletions

Although chromosomal abnormalities are detected by conventional cytogenetic analysis (CCA) in 40-60% of patients with acute myeloid leukemia (AML), cryptic chromosomal deletions may only be detected by molecular analysis. To determine their frequency, we studied 74 cases of AML by microsatellite allelotype assay using 35 microsatellites spanning eight chromosomal regions known to be frequently involved in AML. In 42 (57%) we found DNA imbalance at the screened loci. This was detected by CCA only in 4 cases. Our data show that cryptic deletions are a common event in AML.