Phenylketonuria with normal intelligence and Gowers' muscular dystrophy.

Phenylketonuria is a rare inborn error of metabolism, which is believed to be associated almost always with some degree of mental retardation. The great majority of those affected are idiots or imbeciles; any with an intelligence quotient over 65 are rare enough to merit reporting (e.g., Low, Armstrong and Carlisle, 1956). Gowers' peripheral muscular dystrophy is also a very unusual disease in children. The case reported here showed this extremely rare combination of Gowers' muscular dystrophy, phenylketonuria and an intelligence quotient of over 100. It appeared important, therefore, to determine any metabolic or other differences between this case and other phenylketonurics in the hope of throwing more light on the disease process.