Anhidrotic ectodermal dysplasia Q82.4

Group of genetically different phenotypically largely identical hereditary disease patterns with congenital malformations of skin appendages (hair, sweat glands, sebaceous glands), salivary glands, teeth and nasal cartilage, reduced cellular immunity with normal intelligence.

Christ-Siemens type is the most common form of ectodermal dysplasia.

An(hypo)hidrotic ectodermal dysplasia is a genetic disorder that can be caused by mutations in one of several genes.

These include:

• EDA
• EDAR
• EDARADD
• WNT10A.

Mutations in the EDA gene are the most common cause of this disease, accounting for more than half of all cases. The EDA gene encodes ectodysplasin-A, a protein from the tumor necrosis factor-α ligand family. EDAR, EDARADD and WNT10A gene mutations are each responsible for a smaller percentage of cases. In about 10% of people with hypohidrotic ectodermal dysplasia, the genetic cause is unknown.

The EDA, EDAR and EDARADD genes encode proteins that work together during embryonic development. These proteins are part of a signaling pathway that is crucial for the interaction between two cell layers, the ectoderm and the mesoderm. In the early embryo, these cell layers form the basis for many of the body's organs and tissues. The interactions between the ectoderm and mesoderm are essential for the formation of various structures that arise from the ectoderm, including skin, hair, nails, teeth and sweat glands.

Mutations in the EDA, EDAR or EDARADD gene prevent normal interactions between the ectoderm and mesoderm, which impairs the normal development of skin, hair, nails, teeth and sweat glands. Mutations in one of these three genes lead to the main signs and symptoms of hypohidrotic ectodermal dysplasia described above.

The WNT10A gene encodes a protein that is part of another signaling pathway (Wnt signaling pathway). The Wnt signaling pathway controls the activity of certain genes and regulates the interactions between cells during embryonic development. The signaling pathway in which the WNT10A protein is involved is crucial for the development of ectodermal structures, especially teeth. The WNT10A gene mutations that cause hypohidrotic ectodermal dysplasia impair the function of the protein, disrupting the development of teeth and other structures that arise from the ectodermal cell layer.

When hypohidrotic ectodermal dysplasia is caused by mutations in the WNT10A gene, the features are more variable than with mutations in the EDA, EDAR or EDARADD genes. Signs and symptoms range from mild to severe, and mutations in the WNT10A gene are more likely to result in the absence of all permanent (adult) teeth.

Clarke et al (1987) conducted a linkage study of 24 families with an(hypo)hidrotic ectodermal dysplasia. They concluded that the HED locus is located in the centromeric region between DXYS1 on the long arm and DXS14 on the short arm, probably on the proximal Xq. The authors found that EDA is closely associated with PGK1 (311800). Zonana et al. (1988) extended their earlier linkage study by analyzing 36 families using 10 DNA probes at 9 marker loci. They came to the conclusion that the disorder is localized in the region Xq11-q21.1, probably Xq12-q13. This assignment was later confirmed and more than 60 mutations of the EDA gene have now been described.

Generalized hypotrichosis: sparse scalp hair, absence of eyebrows and eyelashes as well as axillary and pubic hair. Hypohidrosis to anhidrosis, resulting in heat intolerance. Tendency to eczematization due to reduced sebum secretion, ichthyosiform skin condition(ichthyosis). Frequent thin, brittle, grooved nails. Anodontia or hypodontia (missing or conical-hypoplastic teeth). Flat nasal bridge, bulging lips, Olympian forehead. Possible eye disorders, neurolabyrinthine disorders, ozaena, hypo- and dysmastia. Mental and other physical development normal.

Special type: associated with follicular and palmoplantar keratoses and centrofacial lentiginosis. Tendency to otitis media and chronic rhinitis and bronchitis. Female conductors show a lack of sweat glands in some areas and occasionally a hypoplasia of the nipples and a reduction of the teeth. Rarely reduced intelligence, possibly due to hyperthermia in childhood.

Symptomatic. It is important to clarify the accompanying symptoms (e.g. eyes). Avoidance of extreme temperatures and desiccating measures such as long and warm showers, hot baths, etc.

Bland care with oily externals.

If anhidrosis is pronounced, ointments that are too greasy may be perceived as unpleasant. Creams such as Ungt. emulsif. aq., 2-10% urea-containing creams R102 or ointments (e.g. Basodexan S ointment, Eucerin 5% urea cream) have proved effective here. Dental monitoring.

There are several different inheritance patterns in an(hypo)hidrotic ectodermal dysplasia.

Most cases are inherited according to the X-linked pattern and are caused by mutations in the EDA gene. In women who have two copies of the X chromosome, an altered copy of the gene in each cell often results in less severe manifestations of the disease. Signs and symptoms may include some missing or abnormal teeth, thinning hair, and mild problems with sweat gland function.

Less commonly, hypohidrotic ectodermal dysplasia is inherited in an autosomal dominant or autosomal recessive manner. Mutations in the EDAR, EDARADD, or WNT10A gene can cause either autosomal dominant or autosomal recessive an(hypo)hidrotic ectodermal dysplasia. In autosomal dominant inheritance, one copy of the altered gene in each cell is sufficient to cause the disorder. Some affected individuals inherit the mutation from an affected parent. Other cases arise from new mutations in the gene and occur in people who do not have the disease in their family.

Autosomal recessive inheritance means that both copies of the gene have mutations in every cell. The parents of a person with an autosomal recessive disease each carry one copy of the mutated gene. Some mutation carriers have mild signs and symptoms of hypohidrotic ectodermal dysplasia, including a slightly lower ability to sweat and less severe dental abnormalities.

1. Blume-Peytavi U et al (1994) Anhidrotic ectodermal dysplasia. Dermatologist 45: 378-384
2. Carrol ED et al (2003) Anhidrotic ectodermal dysplasia and immunodeficiency: the role of NEMO. Arch Dis Child 88: 340-341
3. Clarke A et al (1987) X-linked hypohidrotic ectodermal dysplasia: DNA probe linkage analysis and gene localization. Hum. Genet. 75: 378-380.
4. Clarke A, Burn J (1991) Sweat testing to identify female carriers of X-linked hypohidrotic ectodermal dysplasia. J Med Genet 28: 330-333
5. Christ J (1913) On the congenital ectodermal defects and their relations to each other; vicariir pigment for hair formation. Archiv für Dermatologie und Syphilis (Berlin) 116: 685-703
6. Darwin C (1875) The variation of animals and plants under domestication. John Murray (London) (2nd ed.): 319
7. Doffinger R et al (2001) X-linked anhidrotic ectodermal dysplasia with immunodeficiency is caused by impaired NF-kappaB signaling. Nat Genet 27: 277-285
8. Happle R, Frosch PJ (1985) Manifestation of the lines of Blaschko in women heterzygous for X-linked hypohidrotic ectodermal dysplasia. Clin Genet 27: 468-471
9. Kobielak K et al (2001) Mutations in the EDA gene in three unrelated families reveal no apparent correlation between phenotype and genotype in patients with an X-linked anhidrotic ectodermal dysplasia. Am J Med Genet 100: 191-197
10. Lexner MO et al (2008) X-linked hypohidrotic ectodermal dysplasia. Genetic and dental findings in 67 Danish patients from 19 families. Clin Genet 74: 252-259.
11. Örge C et al (1991) Multiple sebaceous gland hyperplasias in X-linked hypohidrotic ectodermal dysplasia. Dermatologist 42: 645-647
12. Siemens HW (1937) Studies on inheritance of skin diseases XII. Anhidrosis hipotrichotica. Archiv für Dermatologie und Syphilis (Berlin) 175: 567-577.
13. Touraine A (1936) L'anidrose avec hypotricose et anodontie." (Polydysplasia ectodérmique héréditaire.) La presse médicale (Paris) 44: 145-149.
14. Uner A et al. (2001) Anhidrotic ectodermal dysplasia in a child with a fever of unknown origin. J Dermatol 28: 516-517
15. van Steensel MA M et al (2009) Lelis syndrome may be a manifestation of hypohidrotic ectodermal dysplasia. (Letter) Am. J Med Genet 149A: 1612-1613.
16. Zonana J et al (1987) Prenatal diagnosis of X-linked hypohidrotic ectodermal dysplasia by linkage analysis. Am J Med Genet 35: 132-135.