Mutation identification in a canine model of X-linked ectodermal dysplasia.

X-linked hypohidrotic ectodermal dysplasia (XHED), an inherited disease recognized in humans, mice, and cattle, is characterized by hypotrichosis, a reduced number or absence of sweat glands, and missing or malformed teeth. In a subset of affected individuals and animals, mutations in the EDA gene (formerly EDI), coding for ectodysplasin, have been found to cause this phenotype. Ectodysplasin is a homotrimeric transmembrane protein with an extracellular TNF-like domain, which has been shown to be involved in the morphogenesis of hair follicles and tooth buds during fetal development.

Frequent respiratory tract infections in the canine model of X-linked ectodermal dysplasia are not caused by an immune deficiency.

As in many human patients with X-linked hypohidrotic ectodermal dysplasia (XHED), XHED dogs are at an increased risk for pulmonary disorders. Localized immune system defects had been suspected previously in affected dogs because of frequent infections and unexpected deaths due to opportunistic respiratory tract infections. Experiments were designed to examine systemic and localized humoral and cellular responses, development and function of T cells, and thymic morphology.