title: Proximal 21q deletion as a result of a de novo unbalanced t(12;21) translocation in a patient with dysmorphic features, hepatomegaly, thick myocardium and delayed psychomotor development.
abstract: BACKGROUND
  IInterstitial 21q deletions can cause a wide spectrum of symptoms depending on the size and the location of the deletion. It has previously been suggested that the long arm of chromosome 21 can be divided into three regions based on the clinical severity of the patients and deletion of the region from 32.3 Mb to 37.1 Mb was more crucial than the deletion of other regions.
  
  
  METHODS
  In this study we describe a female patient with dysmorphic features, hepatomegaly, thick myocardium and psychomotor delay. Conventional karyotyping was initially interpreted as full monosomy 21, but subsequent chromosome microarray analysis suggested an approximately 18 Mb partial monosomy. Re-evaluation of the karyotype and fluorescence in situ hybridization revealed deletion of the proximal 21q11.2-q22.11 segment and insertion of 21q22.11-qter to 12qter. The deletion of the present case overlaps with two of the proposed regions including part of the proposed crucial region.
  
  
  CONCLUSIONS
  This report emphasizes the relevance of investigating suspected full monosomies with high resolution methods and FISH in order to investigate the extent of the deletion and the presence of more complex rearrangements.
authors: Department of Clinical Genetics, Applied Human Molecular Genetics, Kennedy Center, Copenhagen University Hospital Rigshospitalet, Glostrup, Denmark.
authors: Cathrine
authors: C
authors: Jespersgaard
authors: Department of Paediatrics, Copenhagen University Hospital, Herlev, Denmark.
authors: Ida N
authors: IN
authors: Damgaard
authors: Department of Clinical Genetics, Applied Human Molecular Genetics, Kennedy Center, Copenhagen University Hospital Rigshospitalet, Glostrup, Denmark.
authors: Nanna
authors: N
authors: Cornelius
authors: Department of Clinical Genetics, Applied Human Molecular Genetics, Kennedy Center, Copenhagen University Hospital Rigshospitalet, Glostrup, Denmark ; Wilhelm Johannsen Centre for Functional Genome Research, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.
authors: Iben
authors: I
authors: Bache
authors: Department of Paediatrics, Copenhagen University Hospital, Herlev, Denmark.
authors: Niels
authors: N
authors: Knabe
authors: Department of Paediatrics, Copenhagen University Hospital, Herlev, Denmark.
authors: Maria J
authors: MJ
authors: Miranda
authors: Department of Clinical Genetics, Applied Human Molecular Genetics, Kennedy Center, Copenhagen University Hospital Rigshospitalet, Glostrup, Denmark.
authors: Zeynep
authors: Z
authors: Tümer
keywords: 21q22; Monosomy 21; Partial monosomy; Translocation