A new mutation in EDA gene in X-linked hypohidrotic ectodermal dysplasia associated with keratoconus.

Hypohidrotic ectodermal dysplasia (HED) was first described in 1848 by Thurnam. HED belongs to ectodermal dysplasias (EDs), which are developmental impairments of ectodermal-derived tissues. X-linked hypohidrotic ectodermal dysplasia (XLHED) is the most common form of the EDs and consists in abnormal development of teeth, hair, and eccrine sweat glands. XLHED is determined by mutations in the ED1 gene, which is responsible for the coding of ectodysplasin-A(EDA-A), a protein that regulates ectodermal appendage formation. In the present study we found both in our proband and in the mother the same missense mutation in exon 9 (c.957 C>A), which resulted in an aminoacid change at position 319 (Ser319Arg). This latter anomaly might alter the charges in the TNF domain of EDA-A, affecting the stability of the protein and therefore the interaction with its receptor. The male propositus presented classical manifestations of HED except for keratoconus (KC) and, to the best of our knowledge, this association has not been previously described. The identification of this new mutation may contribute to evaluating the genotype/phenotype correlations. Finally, this report can give useful information about the genetic basis of KC and HED. Future studies will allow us to understand if a genetic bond exists between them.