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Amino-acid composition in trichorrhexis nodosa.
D H Rushton1, M J Norris, K C James
1School of Pharmacy and Biomedical Sciences, Portsmouth Polytechnic, Cardiff, UK.
Clinical and Experimental Dermatology
|January 1, 1990
Summary
Trichorrhexis nodosa, a hair shaft defect, involves reduced cystine and increased acidic amino acids. Environmental weathering combined with cuticle defects likely causes these hair abnormalities.
Area of Science:
- Dermatology
- Biochemistry
- Genetics
Background:
- Trichorrhexis nodosa is a prevalent hair shaft abnormality.
- It is characterized by nodes along the hair shaft, leading to breakage.
Purpose of the Study:
- To investigate the amino acid composition of hair samples with trichorrhexis nodosa.
- To explore the factors contributing to the formation of nodes in hair shafts.
Main Methods:
- Analysis of amino acid composition in proximal, pre-nodule, nodule, and post-nodule sections of 200 scalp hairs from two females.
- Statistical analysis to compare amino acid levels between different hair sections.
Main Results:
- Significant reductions in cystine (14.3-19.8%) and increases in acidic amino acids were observed in pre-nodule, nodule, and post-nodule sections compared to proximal shaft.
- Nodules predominantly occurred in the distal 10% of the hair shaft.
- Amino acid composition similarities suggest environmental weathering is a key factor.
Conclusions:
- Hair shaft weathering and reduced cuticle coverage are implicated in trichorrhexis nodosa formation.
- A potential genetic defect affecting cuticle polypeptide synthesis may predispose hair to nodule formation under weathering conditions.