7th June 2025

Ectodermal dysplasia

Aetiology

• Occurs when the ectodermal layer of the skin fails to develop
• Vast group of inherited disorders 
  • Primarily involving defects in hair, teeth, nails or sweat glands. 
  • Additionally, tissues of ectodermal origin are often affected which include the ears, eyes, lips, mucous membranes of the mouth or nose and the CNS.
• It is caused by a defect in the transmembrane protein ectodysplasin which is a member of the TNF related ligand proteins involved in the early epithelial-mesenchymal interaction that is essential for the regulation of the ectodermal appendage formation
• They are present from birth and are non-progressive in nature. 
• The classification is based on the presence or absence of the four primary ectodermal dysplasia defects:
  • Dental dysplasia 
  • Trichodysplasia (hair dysplasia)                  
  • Onchodysplasia (nail dysplasia)
  • Dyshidrosis (sweat gland dysplasia)

Diagnosis

• Prenatal testing is available in some centers.
• History                                                        
  • Family history
  • Onset of symptoms (usually at birth- recurrent unexplained fevers)
• Clinical
  • Depends on the organs being affected
  • Sweat glands
    • Absence/reduced sweat gland production results in disrupted thermoregulation which can lead to abnormally high temperatures in children. 
    • Seizures and neurological problems occur as a sequalae.
  • Hair
    • Thinning and sparsity of the hair present in the scalp and body. 
    • The facial, axillary and pubic hairs are usually spared. 
  • Nails
    • Fingernail and toenail abnormalities including thinning, ridging, discoloration, brittle nails, or absence of nails.
  • Teeth
    • Disfigurement in tooth shape, including pointed/peg shaped teeth. Teeth may also be missing
  • Other symptoms:
    • Skin: dryness, pigmentation, thickening leading to cracking, bleeding, and infections
    • Eyes: Keratoconjunctivitis sicca due to lack of tear production. Cataracts and visual defects can occur.
    • Mucous membranes: foul smelling nasal discharge and respiratory infections due to decreased synthesis of normal protective secretions. 
    • Cleft lip/palate
• Histopathology
  • Skin biopsy shows reduced numbers of sweat glands

Management

• Multidisciplinary approach with a team of dentists and doctors.
• General
  • If defective sweat gland production- affected individuals must live in cooler areas/air-conditioned houses which may be very useful in body temperature control
  • Wigs may help improve the cosmetic appearance in people with affected hair 
• Medical
  • Artificial tears may help protection from corneal damage that results from lack of tear production
  • Early dental intervention is essential as some children may require dentures at an early age
• Surgical
  • Surgical repair of cleft lip and palate

Complications

• Seizures and neurological sequalae from defective thermoregulation
• Recurrent chest infections