Anhidrotic ectodermal dysplasia

Anhidrotic ectodermal dysplasia (AED): Description, Causes and Risk Factors:Anhidrotic ectodermal dysplasia characterized by absent or defective sweat glands, saddle-shaped nose, hyperpigmentation around the eyes, malformed or missing teeth, sparse hair, dysplastic nails, smooth, finely wrinkled skin, syndactyly, absent breast tissue, and occasionally mental retardation; X-linked recessive inheritance, caused by mutation in the ED1 gene on chromosome Xq. There is also an autosomal recessive form.Anhidrotic ectodermal dysplasia is a rare disorder. It is commonly transmitted as an X-linked recessive disorder; however, rarely autosomal recessive and autosomal dominant inheritance also been seen.AED manifests as a triad of defects, partial or complete absence of sweat glands, anomalous dentition, and hypotrichosis. Affected children unable to sweat, may experience episodes of high fever in warm environment and may be mistakenly considered to have fever of unknown origin. The typical facies is characterized by frontal bossing, malar hypoplasia, a flattened nasal bridge, recessed columella, thick everted lips, wrinkled hyperpigmented periorbital skin and prominent low set ears. The skin over the entire body is dry, finely wrinkled and hypopigmented and often with prominent venous return. Anodontia or hypodontia with widely spaced, conical teeth are consistent features. Poor development of mucous gland in the respiratory and GI tract may result in increased susceptibility to respiratory infection, purulent rhinitis, dysphonia, and diarrhea.The gene for anhidrotic ectodermal dysplasia was the first X-chromosomal gene whose map position was suggested, based on the occurrence of an X; autosome translocation in a female patient with the disease phenotype. Later linkage studies confirmed the suggested position of the gene at Xq12-q13.1 (XLHED-gene). Mutations in the EDAR gene (2q11-q13) and the EDARADD gene (1q42.2-q43) can also cause AED, but this is considerably rarer.The recent cloning of the gene has led to the identification of a novel transmembrane protein "ectodysplasin" (TNF family ligand) and receptor "edar" (TNF receptor). This TNF ligand and receptor have a developmental regulatory role and are tightly associated with epithelial-mesenchymal interactions and signaling pathways that regulate ectodermal appendage formation and organogenesis during the initiation of development.The prevalence of anhidrotic ectodermal dysplasia is unknown; however, the incidence in male is estimated at 1 in 147,000 births although the condition is usually overlooked in infants.Symptoms:Signs & Symptoms:Forehead appears square with frontal bossing.
  • Sparse hair.
  • Missing teeth.
  • Reduced salivary secretion.
  • Nail dystrophy.
  • Dry skin.
  • Inability to sweat.
  • Mild-to-normal intelligence.
  • Hyperthermia due to lack of sweat glands.
  • Episodes of hyperpyrexia and severe respiratory infections, which may be life-threatening.Anhidrotic ectodermal dysplasia
Diagnosis:Early diagnosis is important to help prevent complications owing to overheating. A Multidisciplinary approach should be involved in diagnosing the syndrome.A detailed family history identifying other family members with anhidrotic ectodermal dysplasia facilitates an early diagnosis. The severity of the condition varies from family-to-family, as well as within families.Approximately 30-40% of affected die during the first 2 years of life as a result of hyperpyrexia or fulminant respiratory infections. The sweating deficit is a reflection of hypoplasia or absence of eccrine glands which may be diagnosed by skin biopsy. Tile palmar skin is an appropriate site for biopsy. Linkage analysis can be used for prenatal and early neonatal diagnosis.Imaging:Perform orthopantomography at an early age if hypodontia or dental abnormalities are present.
  • X-rays of hands, feet, or both may demonstrate specific skeletal deformities.
  • Renal ultrasonography, voiding cystourethrography, and intravenous pyelography may be helpful in evaluating children with anhidrotic ectodermal dysplasia in association with cleft lip and/or palate for underlying Genitourinary tract anomalies.
Treatment:Treatment of these children includes protecting them from exposure to high ambient temperature. Early dental evaluation is necessary so that prosthesis can be provided for cosmetic reasons and for adequate nutrition.Early repair of cleft lip or palate may lessen facial deformities and improve speech. Other midfacial defects or hand/foot deformities may be surgically corrected in order to improve function and reduce physical disfigurement.Allogeneic stem cell transplantation has been performed in a small number of patients with autosomal dominant AED with immunodeficiency (AED-ID); poor engraftment and post-transplant complications were common.NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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