Congenital hair defects.

Congenital hair defects are not just medical curiosities. Congenital hair defects and associated disease entities may represent different manifestations of a basic underlying metabolic defect. Abnormal hair should serve as a clue to other associated abnormalities particularly abnormal amino acid metabolism, neurosensory hearing loss, dental enamel hypoplasia and mental and physical retardation. With application of modern technics to the study of hair, new data have been obtained on the physical and biochemical properties of human hair.