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}

See also

• Palmoplantar keratoderma
• List of cutaneous conditions

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/testing. 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.

Management. 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

• GeneReviews/NCBI/NIH/UW entry on Hidrotic Ectodermal Dysplasia 2
• OMIM entries on Hidrotic Ectodermal Dysplasia 2

References

1. ^ James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0721629210.
2. ^ Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0071380760.

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

CFTR (Cystic fibrosis, Congenital absence of the vas deferens) · CLCN1 (Thomsen disease, Myotonia congenita) · CLCN5 (Dent's disease) · CLCN7 (Osteopetrosis A2, B4 · BEST1 (Vitelliform macular dystrophy) · CLCNKB (Bartter syndrome 3)

TRP channel

TRPC6 (FSGS2) · TRPML1 (Mucolipidosis type IV)

Connexin

GJA1 (Oculodentodigital dysplasia, Hallermann–Streiff syndrome, Hypoplastic left heart syndrome) · GJB1 (Charcot–Marie–Tooth disease X1) · GJB2 (Keratitis–ichthyosis–deafness syndrome, Ichthyosis hystrix, Bart–Pumphrey syndrome, Vohwinkel syndrome) · GJB3/GJB4 (Erythrokeratodermia variabilis, Progressive symmetric erythrokeratodermia) · GJB6 (Clouston's hidrotic ectodermal dysplasia)

Porin

AQP2 (Nephrogenic diabetes insipidus 2)

see also ion channels
B structural (perx, skel, cili, mito, nucl, sclr) · DNA/RNA/protein synthesis (drep, trfc, tscr, tltn) · membrane (icha, slcr, atpa, abct, othr) · transduction (iter, csrc, itra), trfk