Tenascin-X deficient type of Ehlers-Danlos Syndrome

Recognizing the tenascin-X deficient type of Ehlers-Danlos syndrome: a cross-sectional study in 17 patients. – PubMed – NCBI –  Clin Genet. 2016 Sep

The tenascin-X (TNX) deficient type Ehlers-Danlos syndrome (EDS) is similar to the classical type of Ehlers-Danlos syndrome.

Due to the limited awareness among geneticists and the challenge of the molecular analysis of the TNXB gene, the TNX-deficient type EDS is likely to be under diagnosed.

We therefore performed an observational, cross-sectional study. History and physical examination were performed. Results of serum TNX measurements were collected and mutation analysis was performed by a combination of NGS, Sanger sequencing and MLPA. 

Included were 17 patients of 11 families with autosomal recessive inheritance and childhood onset.

All patients had hyperextensible skin without atrophic scarring.

  • Hypermobility of the joints was observed in 16/17 patients.
  • Deformities of the hands and feet were observed frequently.
  • TNX serum level was tested and absent in 11 patients (7 families).

Genetic testing was performed in all families; 12 different mutations were detected, most of which are suspected to lead to non-sense mRNA mediated decay.

In short, patients with the TNX-deficient type EDS typically have

  • generalized joint hypermobility,
  • skin hyperextensibility and
  • easy bruising.

In contrast to the classical type, the inheritance pattern is autosomal recessive and atrophic scarring is absent. Molecular analysis of TNXB in a diagnostic setting is challenging.  

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