X-linked hypohidrotic ectodermal dysplasia is caused by mutation in the gene encoding ectodysplasin-A (EDA) (MIM.300451).
References
Casal ML, Lewis JR, Mauldin EA, Tardivel A, Ingold K, Favre M, Paradies F, Demotz S, Gaide O, Schneider P. Significant correction of disease after postnatal administration of recombinant ectodysplasin a in canine x-linked ectodermal dysplasia. Am J Hum Genet. 2007 Nov;81(5):1050-6. PMID: 17924345