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.