LAUSR

We present a case of genetically confirmed X-linked ectodermal dysplasia (XHED) with the unusual clinical manifestation of palmoplantar keratoderma. Hypohidrotic ectodermal dysplasia (HED, also known as Christ-Siemens-Tourraine syndrome) is characterised by the triad of hypodontia, hypotrichosis and hypohidrosis, whereas palmoplantar keratoderma is a more frequently a feature of hidrotic ectodermal dysplasia 2 (Clouston syndrome). Our patient, a 63-year-old male of non-consanguinous parents, had classical features of HED but also had symmetrical palmoplantar keratoderma present since birth, which had worsened over the past 3-years. Genetic testing confirmed the diagnosis of XHED with a previously reported pathogenic variant in the EDA gene (EDA c.766C>T). A literature search revealed only four previous reports of a clinical presentation of palmoplantar keratoderma in HED, and only one had been confirmed with genetic testing. This case suggests that palmoplantar keratoderma may be considered an uncommon manifestation of XHED, which is important as, despite advances in the understanding of the genetics of ectodermal dysplasia, classification remains clinical for those who do not have access to genetic testing.