Morphological and Biochemical Investigations of Hair in Disturbed Amino Acid Metabolism

The study examined the impact of inborn errors of metabolism on the amino acid content, structure, and growth of human hair in patients with Phenylketonuria, Cystinosis, Homocystinuria, and Tyrosinosis. Using a scanning electron microscope, researchers observed defects in the hair cuticle, such as a plicated pattern, in patients with Phenylketonuria and Cystinosis. Despite these structural abnormalities, the amino acid content of hydrolyzed hair keratin remained within normal ranges, showing no significant changes in phenylalanine, cystine, homocystine, methionine, or tyrosine. Hair growth disturbances were assessed through standardized hair root samples, revealing an increase in hair root atrophy correlating with the severity of the metabolic disorder.