|Year : 2018 | Volume
| Issue : 4 | Page : 355-356
Department of Pathology, Employees' State Insurance Corporation Medical College and PGIMSR, Bengaluru, Karnataka, India
|Date of Web Publication||2-Aug-2018|
Department of Pathology, Employees' State Insurance Corporation Medical College and PGIMSR, Bengaluru - 560 010, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chikkannaiah P. Ectodermal dysplasia. Med J DY Patil Vidyapeeth 2018;11:355-6
Ectodermal dysplasia (ED) is a group of hereditary disorders characterized by developmental abnormalities of ectodermal derivative structure. The incidence of the disease is 1 in 1,00,000. X-linked recessive form (Christ–Siemens–Touraine syndrome) is a more common mode of transmission followed by autosomal dominant (Clouston's syndrome). Autosomal recessive form is rare. In few cases, the family history is not available indicating de novo mutation. Males are commonly affected than females.,,,
ED has been recorded long back in 1792 by Danz. Weech coined the term hereditary ED. In 1838, Wedderburs documented the x-linked mode of transmission of ED in a Hindu family. In 1933, Cockyane described the occurrence of ED in females and documented autosomal dominant and recessive mode of transmission. In 1936, Levit described the de novo concept in ED. In 2015, the first fetal autopsy case of ED was described by Chikkannaiah et al.
ED occurs due to the defects of the genes regulating epithelial and mesenchymal signaling. The defective genes identified are ED-1, muscle segment homeobox homology-1, ectodysplasia-1 (EDAR), paired box genes and human homolog of mouse dl, EDARDD, and WNT 10A. The genes like ED, EDAR and others collectively act to produce protein ectodysplasin-1. This protein is essential in the interaction between ectoderm and mesoderm, which occurs at 6th week of intrauterine life. hence any mutation at this point leads to severe form of ED. ED1 mutations are observed in X-linked recessive form, and EDAR, EDARDD, and WNT 10A mutations are observed in autosomal dominant and recessive inheritance.,
ED is classified based on molecular abnormality and on morphological features. Molecular classifications are Priolo and Lagana classification in 2001 and the Lamartine classification in 2003, but this classification is not practiced as molecular subtyping is not available for all the cases. Morphologically, it is classified as hidrotic/anhidrotic ED (HED) and hypohidrotic ED (HiED), based on the presence of absence of sweating. This classification is used frequently. In another classification, the ED is classified into four different types: ED1 (trichodysplasia), ED2 (dental dysplasia), ED3 (onchodysplasia), and ED4 (dyshidrosis). From these four major types, many subtypes are derived, common being 1-2-3-4.,,,
The morphology of ED varies from case to case. HED which is transmitted as X-linked recessive form is characterized by triad of hypotrochosis, hypohydrosis, and hypodontia. Hypotrochosis is marked by decreased or absent scalp hair, eyebrows, and eyelashes. There is absence of lanugo hair. The hairs on the other body parts are sparse. Hypohydrosis is due to hypoplasia or aplasia of the sweat and sebaceous gland. The other glands such as lacrimal and submucosal glands also show similar changes which lead to dryness of eyes, atrophic rhinitis, mucosal dryness, and repeated infections. There will be decreased both primary and permanant teeth (hypodontia). The eruption of the teeth is delayed. Structural anomalies lead to protrusion of lips. Other abnormalities observed are saddle nose deformity, periorbital wrinkling, and frontal bossing. In a female patient, breast is hypoplastic or aplastic with abnormalities of nipple. Mental retardation is observed in 30%–50% of cases. Corneal and lenticular opacities are also observed in few cases.,
HiED is transmitted as autosomal dominant form. HiED will have all the morphological features similar to HED, except for normal sweat glands and abnormalities of nail. Nails are brittle, spoon shaped and frequently undergo superadded infections.
There are few case reports pertaining to the disease across the world., The disease is relatively rare in Africa, with only few case reports in English literature, first of its kind is by Familusi et al. in 1975.,,,Aliyu. documented two cases of HED in sub-Saharan region; both the sisters had classical signs of HED, they were born of consanguineous marriage, they had no sweating since birth, and the possible mode of transmission was autosomal recessive. Even though morphological features were classical, the reports lack the findings of other family members and genetic study. The occurrence of ED in females and autosomal recessive mode of inheritance is rare.
The diagnosis of the condition is mainly by clinical examination, based on morphological features and pedigree. Skin biopsy will help study the presence or absence of eccrine glands. X-ray of the jaw and othopantogram is needed to study the dentures. Sweat pore test helps diagnose both the affected and carrier individuals and can be used for screening the family members. Molecular tests which identify the gene mutation are considered gold standard for diagnosis. Prenatal diagnosis can be done in suspected cases by chorionic villus biopsy at the 10th week of gestation.,
Treatment for the disease is supportive. Dentures can be offered for the people with oligodontia. Artificial tear and nasal irrigation are used for dryness of eyes and nose. Antimicrobial therapy may be needed for few cases after the appropriate microbiological study. Genetic counseling for the affected family helps in the prevention of the disease.,
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