title: A patient with partial trisomy 21 and 7q deletion expresses mild Down syndrome phenotype.
abstract: BACKGROUND
  Down syndrome (DS) is the most common aneuploidy in live-born individuals and it is well recognized with various phenotypic expressions. Although an extra chromosome 21 is the genetic cause for DS, specific phenotypic features may result from the duplication of smaller regions of the chromosome and more studies need to define genotypic and phenotypic correlations.
  
  
  METHODS
  We report on a 26 year old male with partial trisomy 21 presenting mild clinical symptoms relative to DS including borderline intellectual disability. In particular, the face and the presence of hypotonia and keratoconus were suggestive for the DS although the condition remained unnoticed until his adult age array comparative genomic hybridization (aCGH) revealed a 10.1 Mb duplication in 21q22.13q22.3 and a small deletion of 2.2 Mb on chromosomal band 7q36 arising from a paternal translocation t(7;21). The 21q duplication encompasses the gene DYRK1.
  
  
  CONCLUSIONS
  Our data support the evidence of specific regions on distal 21q whose duplication results in phenotypes recalling the typical DS face. Although the duplication region contains DYRK1, which has previously been implicated in the causation of DS, our patient has a borderline IQ confirming that their duplication is not sufficient to cause the full DS phenotype.
authors: Eurogenetica S.A., Laboratory of Genetics, Athens-Thessaloniki, Greece.
authors: I
authors: I
authors: Papoulidis
authors: Eurogenetica S.A., Laboratory of Genetics, Athens-Thessaloniki, Greece.
authors: E
authors: E
authors: Papageorgiou
authors: Eurogenetica S.A., Laboratory of Genetics, Athens-Thessaloniki, Greece.
authors: E
authors: E
authors: Siomou
authors: Eurogenetica S.A., Laboratory of Genetics, Athens-Thessaloniki, Greece.
authors: E
authors: E
authors: Oikonomidou
authors: Aghia Sophia Children's Hospital, Athens, Greece.
authors: L
authors: L
authors: Thomaidis
authors: Biotechnology Research Laboratories, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors: A
authors: A
authors: Vetro
authors: Dept. of Molecular Medicine, University of Pavia, Italy.
authors: O
authors: O
authors: Zuffardi
authors: Institute of Human Genetics, Jena, Germany.. Electronic address: i8lith@mti.uni-jena.de.
authors: T
authors: T
authors: Liehr
authors: Eurogenetica S.A., Laboratory of Genetics, Athens-Thessaloniki, Greece.
authors: E
authors: E
authors: Manolakos
authors: University of Patras, Medical School, Greece.
authors: Papadopoulos
authors: P
authors: Vassilis
mesh_terms: D000328:Adult; D002872:Chromosome Deletion; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D004314:Down Syndrome / Q000235:genetics*; D056726:Genetic Association Studies / Q000379:methods; D006801:Humans; D008297:Male; D014178:Translocation, Genetic / Q000235:genetics; D014314:Trisomy / Q000235:genetics*
keywords: APP; Array comparative genome hybridization (aCGH); Chromosome 21; DNAJB6; DSCR1; DYRK1; DYRK1A; DnaJ/HSP40 homolog subfamily B member 6; Down syndrome; Down syndrome critical region gene 1; MX1; NCAPG2; OMIM; Online Mendelian Inheritance in Man; PTPRN2; Partial trisomy 21q; Phenotype; UBE3C; VIPR2; WD repeat-containing protein 60; WDR60; amyloid beta (A4) precursor protein; condensin-2 complex subunit G2; dual-specifity tyrosine phosphorylation-regulated kinase 1; dual-specifity tyrosine phosphorylation-regulated kinase 1A; myxovirus resistance 1, mouse, homolog of; tyrosine-protein phosphatase non-receptor type 2; ubiquitin protein ligase E3C; vasoactive intestinal peptide receptor 2