Amino-acid composition in trichorrhexis nodosa

Hereditary hypotrichosis simplex of the scalp

Hereditary hypotrichosis simplex of the scalp is a genetic disorder, characterized by sparse or absent scalp hair without structural defects, in the absence of other ectodermal or systemic abnormalities. Structural hair defects may be presented with a genetic disorder affecting hair growth or part of a congenital syndrome or may indicate underlying metabolic disorders, or may be associated with other diseases. We describe a 26-years-old Persian girl suffering from hypotrichosis simplex of the scalp with trichorrhexis nodosa who had no ectodermal defects and systemic disease.

'Relaxers' damage hair: evidence from amino acid analysis

BACKGROUND

'Relaxers' are used by more than two thirds of African females to straighten hair, with easy grooming and increased length often cited as reasons. A recent study reported relaxed hair lengths much shorter than expected, suggesting increased fragility; the potential for scalp inflammation and scarring alopecia remains unclear.

OBJECTIVE

To investigate the biochemical effects of 'relaxers' on hair.

METHODS

With informed consent, included participants represented 3 groups: natural hair, asymptomatic relaxed hair, and symptomatic (brittle) relaxed hair. Biochemical analysis was performed by using a Biochrom 30 amino acid analyzer. Differences in amino acid levels were assessed using either Wilcoxon rank sum test or matched-pairs signed-rank test.

RESULTS

There was a decrease in cystine, citrulline, and arginine; however, an increase in glutamine was found in all relaxed compared to natural hair. Cystine levels (milligram per gram amino acid nitrogen) were similar in natural proximal and distal hair: 14 mg/g (range, 4-15 mg/g) versus 14 mg/g (range, 12-15 mg/g); P = .139. In asymptomatic relaxed hair, cystine levels were higher in less frequently relaxed samples proximal to scalp: 7.5 mg/g (5.6-12) versus 3.3 mg/g (1.3-9.2); P = .005. Cystine levels in distal asymptomatic relaxed and symptomatic relaxed hair were similar to each other and to those in the genetic hair fragility disease trichothiodystrophy.

LIMITATIONS

It was not possible to analyze lye and no-lye 'relaxers' separately.

CONCLUSIONS

'Relaxers' are associated with reduced cystine consistent with fragile damaged hair. A decrease in citrulline and glutamine has been associated with inflammation; prospective studies are needed to investigate whether or how 'relaxers' induce inflammation.

Trichothiodystrophy without associated neuroectodermal defects

Trichothiodystrophy leading to generalized trichorrhexis nodosa-like hair changes with abnormal hair breakage is described in a 4-year-old girl. A marked deficiency of sulphur and the sulphur-containing amino acid, cystine, was detected in the biochemical analysis of the hair. Further investigation of the hair showed the morphological criteria of trichothiodystrophy. Commonly related symptoms, such as mental retardation, ichthyosis and increased sensitivity to sunlight, were not present in our patient.

Localized trichorrhexis nodosa

Trichorrhexis nodosa is a disorder of the hair shaft in which there is a distinctive response to injury. The hair is fragile and on examination regularly spaced pale 'node-like' swellings may be observed. It may affect normal hair following excessive or repeated trauma, or may occur after minimal trauma if there is an inherent defect in keratin synthesis causing abnormally brittle hair. The diagnosis can be readily made clinically and confirmed microscopically. Treatment is aimed at reducing trauma. We describe a case of localized trichorrhexis nodosa in a patient with otherwise apparently normal hair.

Morphological and biochemical characteristics of trichothiodystrophy-variant hair are maintained after grafting of scalp specimens on to nude mice

Trichothiodystrophy (TTD) is a hair defect associated with abnormal composition of the high-sulphur proteins (HSP). HSP can be modified quantitatively (reduced amount of qualitatively normal HSP: TTD-variant) and qualitatively (TTD). In this study we show that the amino acid composition of hairs collected from the scalp of a patient with TTD-variant (donor) was preserved in hairs produced by donor scalp follicles maintained up to 6 months as grafts on to nude mice. It is the first time that an exceptionally rare, clinically and biochemically well-characterized hair dysplasia has been maintained under laboratory conditions for a long period of time. The linear growth rate of TTD-variant hairs was similar to that of control hairs grown under comparable conditions. The persistence of disease-specific abnormalities in the hair shaft indicates that the TTD-variant mutation is expressed without significant quantitative modifications, and appears independent of systemic host-related factors. This model may serve as a clinically relevant working platform for evaluating regulation of abnormal gene expression in the hair follicle under well-controlled experimental conditions.