Uncombable hair syndrome
|Uncombable hair syndrome|
|Scalp hair in uncombable hair syndrome.|
Uncombable hair syndrome, also known as Pili trianguli et canaliculi,:639 Spun-glass hair, Struwwelpeter syndrome (see Struwwelpeter) and Cheveux incoiffables,:765 is a rare structural anomaly of the hair with a variable degree of effect. It was first reported in the early 20th century. It typically becomes apparent between the ages of 3 months and 12 years.
The hair is normal in quantity and is usually silvery-blond or straw-colored. It is disorderly, it stands out from the scalp, and cannot be combed flat. It can be controlled by braiding methods. The underlying structural anomaly is longitudinal grooving of the hair shaft, which appears triangular in cross section. This is caused by mutations in one of three possible genes, PADI3, TGM, or TCHH3. The characteristic hair shaft anomaly can be demonstrated in asymptomatic family members by scanning electron microscopy. To be noticeable, 50% of hairs must be affected by the structural abnormality. Improvement often occurs in later childhood. An autosomal dominant mode of inheritance has been suggested though an autosomal recessive pattern with varying degrees of penetrance has also been noted. The stiffness of the uncombable hair has been reasoned to be due to the triangular form of the hair shaft in cross section. It has been suggested that the condition may result from premature keratinization of the inner root sheath.
A possible case of uncombable hair syndrome was reported in 1912 by A.F. Le Double and F. Houssay. The syndrome was described in 1973 by A. Dupré, P. Rochiccioli and J.L. Bonafé, who named it "cheveux incoiffables". Later that year it was independently described as "spun-glass hair" by J.D. Stroud and A.H. Mehregan. The famous term was coined in the early eighties.
Other syndromes with hair abnormalities may also show features of uncombable hair syndrome such as Rapp–Hodgkin ectodermal dysplasia syndrome, loose anagen syndrome, EEC syndrome (ectodermal dysplasia, ectrodactyly and cleft lip/palate) and familial tricho-odonto-onychial ectodermal dysplasia with syndactyly. However, unlike these conditions, uncombable hair syndrome alone is not associated with physical, neurologic, or mental abnormalities.
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