X – linked Hypohidrotic Ectodermal Dysplasia and atopic eczema – case report and discussion on mechanisms of eczema

Abstract

X-linked Hypohidrotic Ectodermal Dysplasia (XHED) is an inherited disorder that involves defective development of tissues derived from embryonic ectoderm and it is generally suspected by the triad of hypohidrosis, hypotrichosis and hypodontia.
We report a four-year-old boy with a persistent and severe eczema, anodontia, a sparse, thin and blonde hair, periorbital wrinkling with hyperpigmentation and absence of sweating. Laboratory results showed elevation of total serum IgE and IgE specific to house dust mites and grass pollen. Skin biopsy revealed absence of eccrine and sebaceous glands and hair follicles. The genetic molecular study disclosed a c.463C>T (p.Arg155Cys) mutation of the EDA1 gene, consistent with X-linked HED.
Although XHED has a favorable prognosis, eczema is a major problem and the eczematous characteristics of patient’s skin resemble those of atopic dermatitis. Ceramide profile, reduction of natural moisturizing factors due to hypohidrosis and skin barrier dysfunction elicited by airborne proteins likely contribute to persistent and difficult-to-control AD-like eczema. As a consequence of the rarity of the disease, obtaining a significant number of clinical studies to clarify and validate the pathways involved in skin barrier dysfunction and the consequent eczematous lesions in HED patients will probably remain a challenge.