Frequent loss of heterozygosity without loss of genetic material in acute myeloid leukemia with a normal karyotype.

We performed a whole-genome loss of heterozygosity (LOH) analysis of 32 cases of acute myeloid leukemia with normal karyotype using high-density single nucleotide polymorphism arrays. LOH was found in 20% of cases. We identified two types of LOH: (i) interstitial, characterized by small deletions of genomic DNA (2-8 Mb), and (ii) terminal, involving large (30-90 Mb) telomeric regions. Surprisingly, terminal LOH occurred without loss of genetic material because of deletion of large chromosome regions and their substitution through the duplication of the corresponding regions from the homologous chromosomes (acquired partial uniparental disomy).