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A heterogeneous genetic disorder caused by abnormal development of the ectodermal tissue and characterized by the association of hypohidrosis, hypotrichosis, defective dentition, peculiar facies, abnormal thermoregulation, and exocrine gland insufficiency.

Christ-Siemens-Touraine Syndrome

This 19-year-old man with Christ-Touraine-Siemens syndrome has mild frontal bossing with dry and sparse scalp hair, prominent supraorbital ridges with scanty eyebrows, a depressed and wide nasal bridge (saddle nose), and high and wide cheekbones with a flattened maxilla. The lips are thickened, and the skin is dry with an atopic-like dermatitis. Partial anodontia is present.

Anhidrotic Ectodermal Dysplasia; Hypohidrotic Ectodermal Dysplasia.

This is the condition affecting the “Toothless Men of Sind,” members of a Hindu kindred that resides in the vicinity of Hyderabad (the capital of Andhra Pradesh in India) and was described by Charles Darwin in 1875 and later by K.I. Thadani in 1934.

Approximately 1:100,000 of the general population is affected.

X-linked recessive. The disease is caused by a mutation in the ectodysplasin A gene (ED 1), which has been mapped to Xq12.2-q13.1. As a member of the tumor necrosis factor ligand superfamily, ectodysplasin is a membrane protein involved in signal transduction, promoting not only cell adhesion to the extracellular matrix, but also regulating the development of ectodermal appendages and epithelio-mesenchymal interactions. Although usually only men are affected and women act as carriers of the disease, the clinical picture in heterozygous females is highly variable, ranging from no symptoms to severe disease. Rarely, the disease is transmitted in an autosomal recessive or an autosomal dominant pattern.

The clinical triad of anhidrosis (or hypohidrosis), hypotrichosis, and defective dentition is helpful for diagnostic purposes. Skin biopsy of the palm demonstrates the absence or hypoplasia of sweat glands.

Often the disorder presents in the first year of life with episodes of unexplained hyperpyrexia. Thermography can reveal abnormal skin temperature patterns consistent with altered peripheral vascular perfusion. The skin is abnormally dry (lack of sebum and sweat), and heat loss by evaporation is impaired secondary to hypoplastic/aplastic eccrine sweat glands. Associated features include characteristic facies (frontal bossing, saddle nose, flattened maxilla, small chin), fine, brittle, and scant hair (hypotrichosis), scant or absent eyelashes and eyebrows, onychodysplasia (spoon-shaped nails), aplastic/hypoplastic mammary glands with hypoplastic/absent nipples, and atopic-like dermatitis. Dental anomalies include hypodontia/anodontia, taurodontism (tooth with abnormally short roots and enlarged pulp chamber), and conical crowns. Lacrimation and meibomian glands may be absent or diminished. Respiratory tract mucous glands may be hypoplastic/aplastic, resulting in an increased propensity to bronchitis and pneumonia. Laryngeal incompetence with dry mucosal atrophy (often resulting in hoarse voice) is not uncommon and may contribute to recurrent chest infections. A variable degree of mental retardation may be present. Otherwise the prognosis is good, and survival to adulthood ...

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