Chapter 641 Ectodermal Dysplasias
Ectodermal dysplasia (ED) is a heterogeneous group of disorders characterized by a constellation of findings involving defects of 2 or more of the following: teeth, skin, and appendageal structures including hair, nails, and eccrine and sebaceous glands. Although more than 150 ectodermal dysplasias have been described, the majority are rare and most have not been genetically defined.
Anhidrotic (Hypohidrotic) Ectodermal Dysplasia
The syndrome known as anhidrotic ectodermal dysplasia manifests as a triad of defects: partial absence (hypohidrosis) or complete absence of sweat glands, anomalous dentition, and hypotrichosis. There are 4 recognized types of anhidrotic ectodermal dysplasia (Table 641-1). The X-linked form is most common.
Table 641-1 FOUR RECOGNIZED TYPES OF ANHIDROTIC ECTODERMAL DYSPLASIA
| TYPE | INHERITANCE | GENE DEFECT |
|---|---|---|
| ED-1 | X-linked recessive | Ectodysplasin A (EDA) |
| ED-anhidrotic | Autosomal recessive | Ectodyplasin A anhidrotic receptor (EDAR) |
| EDAR-associated death gene (EDARADD) | ||
| ED-3 | Autosomal dominant | EDAR |
| ED-anhidrotic with immune deficiency |
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