Causes for High Phenylalanine With Normal Tyrosine

Authors:
  • JBJulian L. Berman
    Julian L. Berman
  • GCGeorge C. Cunningham
    George C. Cunningham
  • RDRobert W. Day
    Robert W. Day
  • RFRobin Ford
    Robin Ford
  • DHDavid Y. Y. Hsia
    David Y. Y. Hsia
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Abstract
ALTHOUGH phenylketonuria was described by Asbjörn Fölling1over 30 years ago, it is only recently that we have begun to appreciate the full clinical spectrum of the disorder and to get a critical appraisal of the value of a low-phenylalanine diet in preventing the mental defect in such patients.2 Much of this confusion has come about because of differences in methods of ascertainment for phenylketonuria. In the beginning, it was felt that the disorder could only be detected in the patient who developed clinical symptoms, most prominently mental retardation. As a result, it was believed that all patients with phenylketonuria were mentally defective3and the occasional "atypical" phenylketonuric person with normal or near-normal intelligence was considered to be sufficiently unusual as to be worthy of reporting separately.4Since treatment was of little benefit once mental deficiency was already present, very few data were available on treatment