Phenylketonuria and scleroderma.

Two mentally retarded siblings, one with severe segmental scleroderma and the other with atrophoderma of Pasini and Pierini, were found at the ages of 6 and 10 years to have phenylketonuria (PKU). The belief that a common pathomechanism exists between morphea and atrophoderma of Pasini and Pierini is supported by the case of the two siblings. Disorders in tryptophan metabolism can occur in both PKU and scleroderma. For a low phenylalanine diet to be effective in PKU, it has to be instituted at an early age. Phenylketonuria should be considered in infants and children with sclerodermatous skin lesions.