Clouston's hidrotic ectodermal dysplasia

Clouston's hidrotic ectodermal dysplasia
Classification and external resources
OMIM	129500

Clouston's hidrotic ectodermal dysplasia (also known as "Alopecia congenita with keratosis palmoplantaris," "Clouston syndrome,"^[1]^:571 "Fischer–Jacobsen–Clouston syndrome," "Hidrotic ectodermal dysplasia," "Keratosis palmaris with drumstick fingers," and "Palmoplantar keratoderma and clubbing") is caused by mutations in a connexin gene, GJB6 or connexin-30, characterized by scalp hair that is wiry, brittle, and pale, often associated with patchy alopecia.^[2]^{:507,511,517-16}

Disease characteristics

Hidrotic ectodermal dysplasia 2, or Clouston syndrome (referred to as HED2 throughout this entry) is characterized by partial or total alopecia, dystrophy of the nails, hyperpigmentation of the skin (especially over the joints), and clubbing of the fingers. Sparse scalp hair and dysplastic nails are seen early in life. In infancy, scalp hair is wiry, brittle, patchy, and pale; progressive hair loss may lead to total alopecia by puberty. The nails may be milky white in early childhood; they gradually become dystrophic, thick, and distally separated from the nail bed. Palmoplantar keratoderma may develop during childhood and increases in severity with age. The clinical manifestations are highly variable even within the same family.

Diagnosis

HED2 is suspected after infancy on the basis of physical features in most affected individuals. GJB6 is the only gene known to be associated with HED2. Targeted mutation analysis for the four most common GJB6 mutations is available on a clinical basis and detects mutations in approximately 100% of affected individuals. Sequence analysis is also available on a clinical basis for those in whom none of the four known mutations is identified.

Treatment

Treatment of manifestations: special hair care products to help manage dry and sparse hair; wigs; artificial nails; emollients to relieve palmoplantar hyperkeratosis.

Genetic counseling

HED2 is inherited in an autosomal dominant manner. Most individuals with HED2 have an affected parent; de novo gene mutations have also been reported. Offspring of affected individuals have a 50% chance of inheriting the mutation and being affected. Prenatal testing for pregnancies at increased risk is possible if the disease-causing mutation in an affected family member is known; however, requests for prenatal testing for conditions such as HED2 are not common.

External links

References

↑ James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0-7216-2921-0.
↑ Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.

Diseases of ion channels

Calcium channel

Voltage-gated	CACNA1A Familial hemiplegic migraine 1 Episodic ataxia 2 Spinocerebellar ataxia type-6 CACNA1C Timothy syndrome Brugada syndrome 3 Long QT syndrome 8 CACNA1F Ocular albinism 2 CSNB2A CACNA1S Hypokalemic periodic paralysis 1 Thyrotoxic periodic paralysis 1 CACNB2 Brugada syndrome 4

Ligand gated	RYR1 Malignant hyperthermia Central core disease RYR2 CPVT1 ARVD2

Sodium channel

Voltage-gated	SCN1A Familial hemiplegic migraine 3 GEFS+ 2 Febrile seizure 3A SCN1B Brugada syndrome 6 GEFS+ 1 SCN4A Hypokalemic periodic paralysis 2 Hyperkalemic periodic paralysis Paramyotonia congenita Potassium-aggravated myotonia SCN4B Long QT syndrome 10 SCN5A Brugada syndrome 1 Long QT syndrome 3 SCN9A Erythromelalgia Febrile seizure 3B Paroxysmal extreme pain disorder Congenital insensitivity to pain

Constitutively active	SCNN1B/SCNN1G Liddle's syndrome SCNN1A/SCNN1B/SCNN1G Pseudohypoaldosteronism 1AR

Potassium channel

Voltage-gated	KCNA1 Episodic ataxia 1 KCNA5 Familial atrial fibrillation 7 KCNC3 Spinocerebellar ataxia type-13 KCNE1 Jervell and Lange-Nielsen syndrome Long QT syndrome 5 KCNE2 Long QT syndrome 6 KCNE3 Brugada syndrome 5 KCNH2 Short QT syndrome KCNQ1 Jervell and Lange-Nielsen syndrome Romano–Ward syndrome Short QT syndrome Long QT syndrome 1 Familial atrial fibrillation 3 KCNQ2 BFNS1

Inward-rectifier	KCNJ1 Bartter syndrome 2 KCNJ2 Andersen–Tawil syndrome Long QT syndrome 7 Short QT syndrome) KCNJ11 TNDM3 KCNJ18 Thyrotoxic periodic paralysis 2

Chloride channel

TRP channel

TRPC6
- FSGS2
TRPML1
- Mucolipidosis type IV

Connexin

Porin

AQP2
- Nephrogenic diabetes insipidus 2

See also: ion channels

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