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Arthrochalasia

Arthrochalasia EDS (aEDS)

  • Inheritance
Autosomal dominant
  • Major criteria
  1. Congenital bilateral hip dislocation
  2. Severe general joint hypermobility (GJH), with multiple dislocations/subluxations
  3. Skin hyperextensibility

 

  • Minor criteria
  1. Muscle hypotonia
  2. Kyphoscoliosis
  3. Radiologically mild osteopenia
  4. Tissue fragility, including atrophic scars
  5. Easy bruisable skin

 

  • Minimal criteria suggestive for aEDS:
–Major criterion (1): Congenital bilateral hip dislocation
Plus
–Either major criterion (3): skin hyperextensibility
–Or major criterion (2): severe GJH with multiple dislocations/subluxations and at least two other minor criteria
Confirmatory molecular testing is obligatory to reach a final diagnosis.
  • Molecular basis
aEDS is caused by heterozygous mutations in either COL1A1 or COL1A2, that cause entire or partial loss of exon 6 of the respective gene. No other genes are associated with aEDS.
  • Verification of diagnosis
Molecular screening by Sanger sequencing of COL1A1 and COL1A2, or targeted resequencing of a gene panel that includes these genes, is indicated. When no mutation is identified, this approach should be complemented with a CNV detection strategy to identify large deletions or duplications.
In case of unavailability of genetic testing, SDS PAGE of the pepsin-digested collagen in the medium or cell layer of cultured dermal fibroblasts demonstrates the presence of a mutant pNα1(I) or pNα2(I) chain (precursor procollagen chains in which the carboxy (C)-but not the amino (N)-propetide is cleaved off).
TEM of skin specimens shows loosely and randomly organized collagen fibrils with a smaller and more variable diameter, and an irregular outline. These findings may support the diagnosis, but cannot confirm it.
Absence of a causative mutation in COL1A1 or COL1A2 that leads to complete or partial deletion of the exon 6 of either gene excludes the diagnosis of aEDS.
Resource:

The 2017 international classification of the Ehlers–Danlos syndromes

http://onlinelibrary.wiley.com/doi/10.1002/ajmg.c.31552/full

Congenital hip dislocation is present in all, as well as severe generalized joint hypermobility with recurrent subluxations, skin hyperextensibility with easy bruising, tissue fragility including atrophic scars, muscle hypotonia, kyphoscoliosis, and radiologically mild osteopenia.
Arthrochalasia Type EDS is caused by mutations leading to deficient processing of the amino-terminal end of proa 1(I) [type A] or proa 2 (I) [type B] chains of collagen type I. Inheritance: Autosomal dominant.

Medical Journal Article: 

“Clinical phenotypes and molecular characterisation of three patients with Ehlers-Danlos syndrome type VII.”

 

Click this link below to read entire article:

Clinical phenotypes and molecular characterisation of three patients with Ehlers-Danlos syndrome type VII

Collagen Diagnostic Laboratory – Arthrochalasia VIIA OR VIIB