Ectodermal Dysplasia

• results from the abnormal morphogenesis of cuticular or oral derivatives from embryonal ectoderm.
• encompasses a large, heterogeneous group of inherited disorders that share primary defects in the development of 2 or more tissues derived from ectoderm.

Characterized by:

• poor development or absence of
  • hair
  • teeth
  • nails
  • sweat glands
• hyperextensible skin and easy bruisability
• hypermobile joints

Labs

• Patients with EDS associated with immunodeficiency may have depressed cell-mediated immunity. Delayed hypersensitivity skin test results with phytohemagglutinin, concanavalin A, Candida, and purified protein derivative (tuberculin) antigens may be negative.
• Other tests: Sweat pore counts and skin biopsy may document a sweating deficit and reduced sweat glands.Genetic studies may provide gene localization or detect mutations in families with EDS.
   

Imaging

• Jaw radiographs are indicated for infants with fever of unknown origin and possible hypohidrotic ED; tooth buds may be absent.
• Perform orthopantography (orbiting panoramic radiographs) at an early age if hypodontia or dental abnormalities are present.
• X-ray films of hands, feet, or both may demonstrate specific deformities.
• An intravenous pyelogram or urethrocystography with sonographic examination is used to search for genitourinary tract anomalies when EDS is associated with cleft lip and/or palate

More detailed discussion

• Freire-Maia proposed classification into different subgroups according to the presence or absence of
  • Subgroup 1: trichodysplasia
  • Subgroup 2: dental abnormalities
  • Subgroup 3: onychodysplasia
  • Subgroup 4: dyshidrosis
• The disorders are congenital, diffuse, and nonprogressive.
• To date, more than 150 distinctive syndromes have been described with all possible modes of inheritance
• The most common syndromes within this group are (1) hypohidrotic (anhidrotic) ED and (2) hidrotic ED.
• Several EDSs may manifest in association with midfacial defects, mainly cleft lip and palate. The 3 most commonly recognized entities are (1) ectodermal dysplasia, ectrodactyly, and cleft lip/palate (EEC) syndrome; (2) Rapp-Hodgkin syndrome; and (3) Hay-Wells or ankyloblepharon, ectodermal dysplasia, cleft lip/palate (AEC) syndrome.
   

E-medicine.com, last update Jan 2004
The 5 minute pediatric consult, 3rd ed.