A Congenital Hair Defect: Trichoschisis With Alternating Birefringence and Low Sulfur Content

Abstract

Hair from a four year old white girl with a history of brittle hair since birth did not show any previously reported defect with light microscopy. Examination with polarized light revealed regular alternating areas of birefringence and non-birefringence, suggesting a patterned abnormality of hair keratiniziation. Fractures occurred only in the non-birefringent zones. Examination of hairs from each member of the patient's family, and from normal children of the same age, did not show this pattern. Scanning electron micrographs of the defective hair shaft and fracture sites were compared with normal hair and artificially fractured hair and revealed a marked anatomic defect of the cuticle and of the fracture sites. Stress strain curve analysis of the defective hair showed a very low elongation prior to breakage, usually less than 10%. Friction coefficients between crossed hair pairs were lower than normal and correlated with the defective cuticle formation. Electron-probe x-ray microanalysis of the defective hair shaft revealed a marked deficiency of sulfur, the periodicity of which differs from that found in the normal hair. Total sulfur content of the defective hair shafts was markedly decreased. Copper content of the hair shaft was greater than the normal control. However, the copper content of the root and the root/hair shaft ratio were less than normal. Complete amino acid analysis of the patient's hair demonstrates a major decrease in the amount of cystine-cysteine. Urine amino acid analysis detected two peaks not present in normal urine. Preliminary evidence indicates that the unidentified peaks represent peptides of complex composition. Argininosuccinic acid, reported in association with trichorrhexis nodosa, was not found.