Phenylketonuria is one of the congenital metabolic diseases (“or inborn errors of amino acid metabolism”) that are orphan diseases.

Phenylketonuria was first described in 1934 by the Norwegian Doctor AsbjØrn FØlling, but it was not until 20 years later, in 1954, that Professor Horst Bickel mentioned the introduction of a low phenylalanine diet. It was not until 1962 that Dr Robert Guthrie developed screening.