No function (updated: Sept. 12, 2018)
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
No sequence conservation computed yet.
Total structural coverage: 53%
No model available.
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The reference OMIM entry for this protein is 158000
Monilethrix; mnlix
A number sign (#) is used with this entry because of evidence that monilethrix is caused by heterozygous mutation in the hair cortex keratin genes KRTHB1 (KRT81; 602153) and KRTHB6 (KRT86; 601928). There is also evidence that monilethrix is caused by heterozygous mutation in the KRTHB3 gene (KRT83; 602765). One such patient has been reported.
DESCRIPTION
Individuals with monilethrix have normal hair at birth, but within the first few months of life develop fragile, brittle hair that tends to fracture and produce varying degrees of dystrophic alopecia. In the mildest forms, only the occipital regions of the scalp are involved; however, in severe forms the eyebrows, eyelashes, and secondary sexual hair may also be involved. Follicular hyperkeratosis with predilection for the scalp, nape of neck, and extensor surfaces of the upper arm and thighs is also a characteristic finding in these patients. Light microscopic examination is diagnostic and reveals elliptical nodes of normal thickness and intermittent constrictions (internodes) at which the hair easily breaks. There may be spontaneous improvement with time, especially during puberty and pregnancy, but the condition never resolves completely (summary by Zlotogorski et al., 2006). An autosomal recessive form of monilethrix-like congenital hypotrichosis (see
607903) is caused by mutation in the DSG4 gene (
607892). The clinical picture of autosomal recessive monilethrix is more severe than the dominant form, with more extensive alopecia of the scalp, body, and limbs, and a papular rash involving the extremities and periumbilical region (Zlotogorski et al., 2006). The term monilethrix derives from the Latin word for necklace and the Greek for hair (Schweizer, 2006).
CLINICAL FEATURES
Salamon and Schnyder (1962) reviewed the clinical findings in 4 previously reported Swiss families segregating autosomal dominant monilethrix. Hypotrichosis may be the presenting manifestation. The degree of hypotrichosis is variable from patient to patient and from time to time in the same individual. Perifollicular hyperkeratosis is a consistent feature. Microscopically, the hair is beaded. The beading is the result of a periodic narrowing of the shaft with nodes separated by about 0.7 mm (Ito et al., 1984). Expression of monilethrix is variable; in mild cases, dystrophic hair may be confined to the occiput but more severely affected individuals have near total hair loss. In some cases, the hair loss persists throughout life; in others, regrowth of apparently normal hair may occur in adolescence or, temporarily, in pregnancy. Healy et al. (1995) reviewed the phenomenon of beading in this disorder. It had been shown that the periodicity is not diurnal and that it is not synchronous in independent follicles. In mild cases, close inspection is needed to confirm the presence of a few typical beaded hairs. Follicular keratosis and, in some families (Heydt, 1963), nail defects are associated. Electron microscopic studies of affected hair shafts showed defects in the microfibrillar structure of the cortex of the hair shaft and amorphous clumps of cysteine-rich material in both nodal and internodal regions. Hence, the genes for the structural proteins of the hair shaft were considered candidates for causative defects in monilethrix. The major structural proteins of hair are the relatively cysteine-rich 'hard' keratins, also found in nail. Winter et al. (2000) reported a 3-generation French family ...
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Subscribe to this protein entry history
Oct. 20, 2018: Protein entry updated
Automatic update: OMIM entry 158000 was added.
Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).