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Total absence of the α2(I) chain of collagen type I causes a rare form of Ehlers-Danlos syndrome with hypermobility and propensity to cardiac valvular problems
  1. F Malfait1,
  2. S Symoens1,
  3. P Coucke1,
  4. L Nunes2,
  5. S De Almeida2,
  6. A De Paepe1
  1. 1Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
  2. 2Medical Genetics Service, Hospital Dona Estefania, Lisbon, Portugal
  1. Correspondence to:
 Dr Anne De Paepe
 Center for Medical Genetics, Ghent University Hospital, De Pintelaan 185, B-9000 Ghent, Belgium; Anne.Depaepe{at}


Background: Heterozygous mutations in the COL1A1 or COL1A2 gene encoding the α1 and α2 chain of type I collagen generally cause either osteogenesis imperfecta or the arthrochalasis form of Ehlers-Danlos syndrome (EDS). Homozygous or compound heterozygous COL1A2 mutations resulting in complete deficiency of the proα2(I) collagen chains are extremely rare and have been reported in only a few patients, albeit with variable phenotypic outcome.

Methods: The clinical features of the proband, a 6 year old boy, were recorded. Analysis of proα and α-collagen chains was performed by SDS-polyacrylamide gel electrophoresis using the Laemmli buffer system. Single stranded conformation polymorphism analysis of the proband’s DNA was also carried out.

Results: In this report we show that complete lack of proα2(I) collagen chains can present as a phenotype reminiscent of mild hypermobility EDS during childhood.

Conclusions: Biochemical analysis of collagens extracted from skin fibroblasts is a powerful tool to detect the subset of patients with complete absence of proα2(I) collagen chains, and in these patients, careful cardiac follow up with ultrasonography is highly recommended because of the risk for cardiac valvular problems in adulthood.

  • EDS, Ehlers-Danlos syndrome
  • NMD, nonsense-mediated mRNA decay
  • OI, osteogenesis imperfecta
  • PTC, premature termination codon
  • SDS-PAGE, SDS-polyacrylamide gel electrophoresis
  • SSCP analysis, single stranded conformation polymorphism analysis
  • collagen
  • Ehlers-Danlos syndrome
  • joint hypermobility
  • homozygous mutation

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  • This work is supported by grant G.0171.05 from the Fund for Scientific Research-Flanders and a GOA research grant from Ghent University to ADP. FS is a research fellow of the Fund for Scientific Research-Flanders.

  • Competing interests: none declared

  • Written informed consent was obtained from the patient and his parents for the publication of his details