title: Somatic CEBPA mutations are a frequent second event in families with germline CEBPA mutations and familial acute myeloid leukemia.
abstract: OBJECTIVE
  The transcription factor CCAAT/enhancer binding protein-alpha (CEBPA) is crucial for normal myeloid differentiation. Mutations in the CEBPA gene are found in subsets of patients with acute myeloid leukemia (AML). Recently, three families were reported in whom several family members had germline CEBPA mutations and subsequently developed AML. Whereas familial AML is considered a rare event, the frequency of CEBPA germline mutations in AML is not known.
  
  
  METHODS
  In this study, we screened 187 consecutive AML patients for CEBPA mutations at diagnosis. We detected 18 patients (9.6%) with CEBPA mutations. We then analyzed remission samples and constitutive DNA from these patients.
  
  
  RESULTS
  We found that two (11.1%) of 18 AML patients with CEBPA mutations carried a germline N-terminal frameshift CEBPA mutation. Interestingly, additional members in the families of both of these patients have been affected by AML, and the germline CEBPA mutations were also observed in these patients. Additional somatic mutations in AML patients with germline CEBPA mutations in the two families comprised in-frame C-terminal CEBPA mutations in two patients, two nonsilent CEBPA point mutations in one patient, and monosomy 7 in one patient.
  
  
  CONCLUSIONS
  This study shows, for the first time to our knowledge, that germline CEBPA mutations are frequently observed among AML patients with CEBPA mutations. Including the families with germline CEBPA mutations reported previously, additional somatic CEBPA mutations represent a frequent second event in AML with germline CEBPA mutations. Our data strongly indicate that germline CEBPA mutations predispose to AML and that additional somatic CEBPA mutations contribute to the development of the disease.
authors.affiliation: Department of Medical Oncology, University Hospital, Bern, Switzerland. thomas.pabst@insel.ch
authors.forename: Thomas
authors.initials: T
authors.lastname: Pabst
authors.forename: Marianne
authors.initials: M
authors.lastname: Eyholzer
authors.forename: Simon
authors.initials: S
authors.lastname: Haefliger
authors.forename: Julian
authors.initials: J
authors.lastname: Schardt
authors.forename: Beatrice U
authors.initials: BU
authors.lastname: Mueller