Sibs with mental and physical retardation and trichorrhexis nodosa with abnormal amino acid composition of the hair.

Trichorrhexis nodosa is a condition in which individual hairs develop areas where the shaft has split longitudinally into numerous small fibres. The hairs eventually break at these points leaving brush-like ends. Usually trichorrhexis nodosa results from mechanical trauma or harsh chemical treatment (Chernosky and Owens, 1966), but two inherited disorders, argininosuccinic aciduria (Allan et al., 1958; Levin, Mackay, and Oberholzer, 1961; Westall, 1960) and a type of sex-linked neurodegeneration (Menkes et al., 1962), are often associated with a very marked degree of trichorrhexis nodosa. This is a report of a brother and sister with another syndrome, showing mental and physical retardation, trichorrhexis nodosa, and other hair defects.