Facial Anthropometry in Hypohidrotic Ectodermal Dysplasia (HED)

Abstract

Ectodermal dysplasias are a large and heterogeneous group of heritable disorders, with an estimate prevalence of 1/100,000 births. Hypohidrotic ectodermal dysplasia (HED) is the most frequent ED variant, and it is identified by the triad of hypotrichosis, hypohidrosis, and hypodontia. Patients with HED also have an abnormal craniofacial morphology. Common phenotypic characteristic of patients suffering from HED is a generalized, but non-uniform, reduction of facial and head dimensions as compared to normal subjects. In particular, there is frontal bossing, reduced vertical facial height and cranial base width, maxillary and mandibular hypoplasia with small hard tissue palate, high-set orbits with increased biorbital and intercanthal widths, and prominent chin. Facial convexity in the horizontal plane (in all three facial thirds) is increased. The nose and ears are narrow and short, the mouth is narrow with protuberant and everted lips. The nasio-labial angle is acute, the supramental sulcus increased, and the vermilion area of the lips augmented. The midface hypoplasia produces a skeletal Class III tendency (maxillary retrusion associated with mandibular protrusion) with flat or concave facial profile, and the reduction of the vertical dimension turns out an “aged” appearance. Overall, the largest deviations from the norm are found in facial height and anterior-posterior dimensions of facial lower two-thirds, while facial widths are more similar to reference values. Patients with HED have extensive lack of both deciduous and permanent teeth and with hypoplasia of the alveolar processes. The severe facial and dental deficiencies induce alterations not only in masticatory function and in spoken communication, but also in esthetics, with subsequent psychological problems of self-confidence. Overall, the facial soft-tissue of subjects with HED can be successfully measured and monitored with non-invasive computerized anthropometry. Diagnosis, treatment planning, and evaluation of results can be based on global, three-dimensional, quantitative assessment of the craniofacial characteristics of patients with HED. Both the hard- and the soft-tissue structures should be analyzed to provide a complete evaluation of any patient, and should be compared to those of healthy subjects of the same age, sex, race, and ethnic group.