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South African Dental Journal

On-line version ISSN 0375-1562
Print version ISSN 0011-8516

Abstract

ROBERTS, TS.  and  CHETTY, M.. Hypohidrotic Ectodermal Dysplasia: Genetic aspects and clinical implications of hypodontia. S. Afr. dent. j. [online]. 2018, vol.73, n.4, pp.253-256. ISSN 0375-1562.

Hypohidrotic Ectodermal Dysplasia (HED) is a rare genetic disorder, characterised by a distinctive facies, hypotrichosis and hypohidrosis. Hypodonita/ogligodontia is a significant component of the condition, contributes to aesethic and functional problems and may require special dental management. Furthermore, specific dental changes may alert the practitioner to the possible diagnosis of HED. Contemporary investigations to elucidate the molecular pathogenesis of HEDS have drawn attention to the disorder. For this reason, we have reviewed the genetic basis of HED and in particular hypodontia/oligodontia in the light of our own experiences and provided a literature search. Different approaches to the dental management and treatment options in hypodontia/oligodontia in HED are also included. The Ectodermal dysplasias (OMIM 305100) are a group of more than 150 hereditary disorders that affect tissues and organs derived from the ectodermal germ layer. The most common variants of ED are the hidrotic and hypohidrotic (anhidrotic) forms. The distinguishing feature between the two types is the presence or absence of sweat glands. Persons affected by Hypohidrotic Ectodermal Dysplasia (Christ-Siemens-Touraine syndrome) have characteristic facies, including frontal bossing, a depressed nasal bridge I saddle-shaped nose and hyperkeratosis.1 The congenital absence of teeth results in excessive resorption of the alveolar bone, a reduction in the height of the face and full lips. Fine, pigmented, linear wrinkles around the eyes are frequently seen. Symptoms arising from impaired mucous production are common, including upper respiratory infections, otitis, dysphagia and bronchitis.2 Specialised radiographic techniques can be used to detect the reduced sizes of all craniofacial bones. Apart from the otolaryngeal changes, general health is usually good, and the intellect is unimpaired. The inheritance of HED is by either an autosomal, dominant, autosomal recessive or X-linked patterns. Four gene mutations are linked to the pathogenesis of HED. The EDA1 gene mutation is associated with the X-linked variant and EDAR, and EDARADD mutations are associated with the autosomal dominant and autosomal recessive forms.3 WNT10A mutations have been linked to HED patients who have distinct phenotypic expressions Including striking dental changes without facial changes. HED is uncommon. Nguyen-Nielsen et al. reported the frequency of HED in the Danish population to be 1.6 per 100,000 in molecularly confirmed affected persons.4 The primary dental feature, hypodontia/oligodontia, occurs in both dentitions and may lead to mastication problems, impaired speech and poor aesthetics. Xerostomia as a result of hypoplastic salivary glands may predispose the existing teeth to dental caries. For these reasons, dental management is an essential aspect of the well-being of affected persons.

Keywords : Dental; Genetic; Hypodontia.

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