Beschreibung:
<jats:p>The tenascin‐X (<jats:styled-content style="fixed-case">TNX</jats:styled-content>) deficient type Ehlers–Danlos syndrome (<jats:styled-content style="fixed-case">EDS</jats:styled-content>) is similar to the classical type of EDS. Because of the limited awareness among geneticists and the challenge of the molecular analysis of the <jats:italic>TNXB gene</jats:italic>, the <jats:styled-content style="fixed-case">TNX</jats:styled-content>‐deficient type <jats:styled-content style="fixed-case">EDS</jats:styled-content> is probably to be under diagnosed. We therefore performed an observational, cross‐sectional study. History and physical examination were performed. Results of serum <jats:styled-content style="fixed-case">TNX</jats:styled-content> measurements were collected and mutation analysis was performed by a combination of next‐generation sequencing (<jats:styled-content style="fixed-case">NGS</jats:styled-content>), Sanger sequencing and multiplex ligation‐dependent probe amplification (<jats:styled-content style="fixed-case">MLPA</jats:styled-content>). 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 of 17 patients. Deformities of the hands and feet were observed frequently. <jats:styled-content style="fixed-case">TNX</jats:styled-content> serum level was tested and absent in 11 patients (seven families). Genetic testing was performed in all families; 12 different mutations were detected, most of which are suspected to lead to non‐sense <jats:styled-content style="fixed-case">mRNA</jats:styled-content> mediated decay. In short, patients with the <jats:styled-content style="fixed-case">TNX</jats:styled-content>‐deficient type <jats:styled-content style="fixed-case">EDS</jats:styled-content> 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 <jats:italic>TNXB</jats:italic> in a diagnostic setting is challenging.</jats:p>