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Frequent Partial Uniparental Disomy Due to Somatic Recombination in Acute Myeloid Leukemias

ABSTRACT: Genome-wide analysis of single nucleotide polymorphisms in 64 acute myeloid leukemias has revealed that 20% exhibited large regions of homozygosity that could not be accounted for by visible chromosomal abnormalities in the karyotype. Further analysis confirmed that these patterns were due to partial uniparental disomy (UPD). Remission bone marrow was available from five patients showing UPD in their leukemias, and in all cases the homozygosity was found to be restricted to the leukemic clone. Two examples of UPD11p were shown to be of different parental origin as indicated by the methylation pattern of the H19 gene. Furthermore, a previously identified homozygous mutation in the CEBPA gene coincided with a large-scale UPD on chromosome 19. These cryptic chromosomal abnormalities, which seem to be nonrandom, have the characteristics of somatic recombination events and may define an important new subclass of leukemia. Patient No. from Table 1 of Raghavan et al 2005 and Sample name Patient No: 1 = Sample name: AML sample 35 diagnosis Patient No: 1 = Sample name: AML sample 107 remission Patient No: 2 = Sample name: AML sample 37 diagnosis Patient No: 3 = Sample name: AML sample 10 diagnosis Patient No: 3 = Sample name: AML sample 44 remission Patient No: 4 = Sample name: AML sample 20 diagnosis Patient No: 5 = Sample name: AML sample 65 diagnosis Patient No: 6 = Sample name: AML sample 69 diagnosis Patient No: 6 = Sample name: AML sample 94 remission Patient No: 7 = Sample name: AML sample 40 diagnosis Patient No: 7 = Sample name: AML sample 41 remission Patient No: 8 = Sample name: AML sample 64 diagnosis Patient No: 9 = Sample name: AML sample 7 diagnosis Patient No: 10 = Sample name: AML sample 49 diagnosis Patient No: 10 = Sample name: AML sample 106 remission Patient No: 11 = Sample name: AML sample 76 diagnosis Patient No: 12 = Sample name: AML sample 79 diagnosis Keywords: DNA copy number, loss of heterozygosity

ORGANISM(S): Homo sapiens

PROVIDER: GSE7490 | GEO | 2007/04/11

SECONDARY ACCESSION(S): PRJNA100311

REPOSITORIES: GEO

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Project description:Genome-wide analysis of single nucleotide polymorphisms in 64 acute myeloid leukemias has revealed that 20% exhibited large regions of homozygosity that could not be accounted for by visible chromosomal abnormalities in the karyotype. Further analysis confirmed that these patterns were due to partial uniparental disomy (UPD). Remission bone marrow was available from five patients showing UPD in their leukemias, and in all cases the homozygosity was found to be restricted to the leukemic clone. Two examples of UPD11p were shown to be of different parental origin as indicated by the methylation pattern of the H19 gene. Furthermore, a previously identified homozygous mutation in the CEBPA gene coincided with a large-scale UPD on chromosome 19. These cryptic chromosomal abnormalities, which seem to be nonrandom, have the characteristics of somatic recombination events and may define an important new subclass of leukemia. Patient No. from Table 1 of Raghavan et al 2005 and Sample name; Patient No: 1 = Sample name: AML sample 35 diagnosis; Patient No: 1 = Sample name: AML sample 107 remission; Patient No: 2 = Sample name: AML sample 37 diagnosis; Patient No: 3 = Sample name: AML sample 10 diagnosis; Patient No: 3 = Sample name: AML sample 44 remission; Patient No: 4 = Sample name: AML sample 20 diagnosis; Patient No: 5 = Sample name: AML sample 65 diagnosis; Patient No: 6 = Sample name: AML sample 69 diagnosis; Patient No: 6 = Sample name: AML sample 94 remission; Patient No: 7 = Sample name: AML sample 40 diagnosis; Patient No: 7 = Sample name: AML sample 41 remission; Patient No: 8 = Sample name: AML sample 64 diagnosis; Patient No: 9 = Sample name: AML sample 7 diagnosis; Patient No: 10 = Sample name: AML sample 49 diagnosis; Patient No: 10 = Sample name: AML sample 106 remission; Patient No: 11 = Sample name: AML sample 76 diagnosis; Patient No: 12 = Sample name: AML sample 79 diagnosis Experiment Overall Design: DNA from 64 diagnostic AML samples were analysed using Affymetrix 10K SNP arrays. Large regions of homozygosity were identified and compared with remission bone marrow where available.

Project description:We analysed, by last-generation high-resolution SNP arrays, Normal Karyotype (NK)-AML patients at diagnosis (Dx) and remission (R) phases, in order to determine the number of tumor-associated copy number abnormalities (CNAs) and copy neutral-loss of heterozygosity (CN-LOH) regions per patient and to identify possible recurring genomic abnormalities. The number of tumor-associated CNAs was detemined after comparison of 11 matched Dx/R samples using stringent conditions able to reduce the number of false positive CNAs. 8 additional unmatched Dx samples were included in the analysis of recurring CNAs and for detection of broad CN-LOH segments. With the exception of a single outlier case, a low number of CNAs per patient was detected (median value of 1 somatic loss or gain per patient). However, a high prevalence of CNAs (60-70% of the patients showed at least 1 tumor-associated gain or loss) and few recurring CNAs were observed, thus providing new hints towards identification of cooperating mutations. An extensive search of all CN-LOH regions > 1 Mb revealed only 3 broad regions (terminal 12Mb of 22q, terminal 27Mb of 1p and the whole chromosome 21) in three patients out of 19 (16%). CN-LOH of the whole chromosome 21 was responsible for homozygosity of a missense mutation (R80C) of RUNX1/AML1. Our study suggests that a relative submicroscopic copy number stability NK-AML genomes is associated with low recurrence of specific CNAs and CN-LOH in NK-AML patient population. Nineteen AML bone marrow samples were collected at the time of diagnosis (>90% blasts), defined as karyotypically-normal on the basis of standard metaphase cytogenetics (MC) and analysed by the Affymetrix SNP 6.0 arrays. In 11 of such cases (matched Dx) we obtained a bone marrow sample at the remission phase (matched R) of comparable high quality as evaluated by Contrast QC and MAPD values. In 8 cases (unmatched Dx) the corresponding R sample was not available or was not of comparable quality. As a reference set the publicly available data from 270 HapMap individuals were used.

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Frequent Partial Uniparental Disomy Due to Somatic Recombination in Acute Myeloid Leukemias

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