An inborn error of metabolism with the urinary excretion of alpha-hydroxy-butyric acid and phenylpyruvic acid.

We have recently seen a baby girl with gross mental deficiency who had repeated attacks of generalized oedema. She also had an extremely unpleasant, pungent smell due to the presence in her urine of a substance derived from ox-hydroxy-butyric acid. So far as we know, this acid has not previously been detected in human urine. The urine also contained phenylpyruvic acid and phenylacetic acid as well as an excess of certain amino-acids. We believe that the infant had a double metabolic abnormality. One was the familiar defect of phenylketonuria in which a block in the conversion of phenylalanine to tyrosine leads to the accumulation of phenylalanine in the body and to the excretion in the urine of phenylpyruvic acid, phenylacetic acid and other derivatives of phenylalanine (Jervis, 1954). The urinary excretion of oc-hydroxybutyric acid cannot be related to the metabolism of phenylalanine and indicates the presence of another metabolic defect.