Consequences of X-Linked Hypohidrotic Ectodermal Dysplasia for the Human Jaw Bone

Mutations of the Eda gene, which encodes for ectodys-plasin-A1, result in X-linked hypohydrotic ectodermal dysplasia (XLHED). This pathology may lead to severe oligodontia, subsequently requiring implant therapy. Since Eda is suspected to participate in bone development, the jaw bone status was investigated in XLHED patients in order to adjust the surgical protocol. Using computed tomography, densitometric profiles and 3D reconstructions, the bone structure was analyzed and compared to that of control individuals; our results showed that the morphological changes comprised mandibular bone flattening. Craniofacial CT scans showed medullary bone hyperdensity, including in the mandibular symphysis area, where implants must be placed. These alterations in bone structure were also observed in locations where the presence/absence of teeth cannot interfere. If the changes in jaw bone morphology can be a consequence of oligodontia, the changes in bone structure seem to be tooth-independent and suggest a direct effect of the mutation on bone formation and/or remodeling.