Résumé
P>Background
Hypohidrotic ectodermal dysplasia (HED) is characterized by abnormal development of the eccrine sweat glands, hair and teeth. The X-linked form of the disease, caused by mutations in the EDA gene, represents the majority of HED cases. Autosomal dominant and recessive forms occasionally occur and result from mutations in at least two other genes: EDAR and EDARADD. EDARADD interacts with the TAB2/TRAF6/TAK1 complex, which is necessary for NF-kappa B activation by EDAR.
Objectives
To determine frequency of EDARADD, TRAF6, TAB2 and TAK1 mutations in HED.
Materials and methods
We have screened 28 familial or sporadic HED cases with no mutations in the EDA and EDAR genes for EDARADD, TRAF6, TAB2 and TAK1 mutations.
Results
We identified one EDARADD 6-bp homozygous in-frame deletion (c.402-407del, p.Thr135-Val136del) in a patient born to consanguineous parents. Functional studies showed that the p.Thr135-Val136del impaired the EDAR-EDARADD interaction and then severely inhibited NF-kappa B activity. In the remaining 27 patients, we failed to find causative mutations in EDARADD, or in TRAF6, TAB2 or TAK1.
Conclusions
Our study demonstrates that EDARADD mutations are not a frequent cause of HED, while mutations in TRAF6, TAB2 and TAK1 may not be implicated in this disease.