title: Haploinsufficiency of ETV6 and CDKN1B in patients with acute myeloid leukemia and complex karyotype.
abstract: BACKGROUND
  Acute myeloid leukemia with complex karyotype (CK-AML) is a distinct biological entity associated with a very poor outcome. Since complex karyotypes frequently contain deletions of the chromosomal region 12p13 encompassing the tumor suppressor genes ETV6 and CDKN1B, we aimed to unravel their modes of inactivation in CK-AML.
  
  
  RESULTS
  To decipher deletions, mutations and methylation of ETV6 and CDKN1B, arrayCGH, SNP arrays, direct sequencing of all coding exons and pyrosequencing of the 5'UTR CpG islands of ETV6 and CDKN1B were performed. In total, 39 of 79 patients (49%) showed monoallelic deletions of 12p13 according to karyotypic data and 20 of 43 patients (47%) according to genomic profiling. Genomic profiling led to the minimal deleted region covering the 3'-UTR of ETV6 and CDKN1B. Direct sequencing revealed one novel monoallelic frameshift mutation in ETV6 while no mutations in CDKN1B were identified. Furthermore, methylation levels of ETV6 and CDKN1B did not indicate transcriptional silencing of any of these genes. ETV6 and CDKN1B had reduced expression levels in CK-AML patients with deletion in 12p13 as compared to CK-AML without deletion in 12p13, while the other genes (BCL2L14, LRP6, DUSP16 and GPRC5D) located within the minimal deleted region in 12p13 had very low or missing expression in CK-AML irrespective of their copy number status.
  
  
  CONCLUSIONS
  ETV6 and CDKN1B are mainly affected by small monoallelic deletions, whereas mutations and hypermethylation play a minor role in CK-AML. Reduced gene dosage led to reduced gene expression levels, pointing to haploinsufficiency as the relevant mechanism of inactivation of ETV6 and CDKN1B in CK-AML.
authors.forename: Simone
authors.initials: S
authors.lastname: Feurstein
authors.forename: Frank G
authors.initials: FG
authors.lastname: Rücker
authors.forename: Lars
authors.initials: L
authors.lastname: Bullinger
authors.forename: Winfried
authors.initials: W
authors.lastname: Hofmann
authors.forename: Georgi
authors.initials: G
authors.lastname: Manukjan
authors.forename: Gudrun
authors.initials: G
authors.lastname: Göhring
authors.forename: Ulrich
authors.initials: U
authors.lastname: Lehmann
authors.forename: Michael
authors.initials: M
authors.lastname: Heuser
authors.forename: Arnold
authors.initials: A
authors.lastname: Ganser
authors.forename: Konstanze
authors.initials: K
authors.lastname: Döhner
authors.forename: Brigitte
authors.initials: B
authors.lastname: Schlegelberger
authors.affiliation: Institute of Cell and Molecular Pathology, Hannover Medical School, Hannover, Germany. Steinemann.Doris@mh-hannover.de.
authors.forename: Doris
authors.initials: D
authors.lastname: Steinemann
mesh_terms: D056905:Chromosome Breakpoints; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D002881:Chromosomes, Human, Pair 12; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics*; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D018628:Gene Dosage; D020869:Gene Expression Profiling; D056726:Genetic Association Studies; D023281:Genomics; D057895:Haploinsufficiency; D006801:Humans; D059785:Karyotype; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D009154:Mutation; D050783:Proto-Oncogene Proteins c-ets / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D000097764:ETS Translocation Variant 6 Protein
chemical_list: D050760:Cyclin-Dependent Kinase Inhibitor p27; D050783:Proto-Oncogene Proteins c-ets; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53; D000097764:ETS Translocation Variant 6 Protein