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Phenylalanine supplementation improves the phenylalanine profile in tyrosinaemia
Author(s) -
Wilson C. J.,
Van Wyk K. G.,
Leonard J. V.,
Clayton P. T.
Publication year - 2000
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1023/a:1005666426079
Subject(s) - phenylalanine , tyrosine , tyrosinemia , phenylalanine hydroxylase , amino acid , medicine , endocrinology , tyrosine aminotransferase , chemistry , enzyme , biochemistry , enzyme inducer
Tyrosinaemia types I and II are caused by enzyme deficiencies in the tyrosine catabolism pathway. Successful treatment is possible with the novel enzyme inhibitor NTBC in tyrosinaemia type I and with dietary tyrosine and phenylalanine restriction in both conditions. This is achieved with a low natural protein intake and a supplementary amino acid formula that is phenylalanine‐ and tyrosine‐free. Patients on this regimen had been noted, periodically, to have very low plasma phenylalanine concentrations (<20 μmol/L). The tyrosine and phenylalanine profiles in six patients were measured. Five of the six patients had very low concentrations of phenylalanine during the later half of the day. The response to phenylalanine supplementation was assessed and supplementing the diet with phenylalanine 30–40 mg/kg per day resulted in normal concentrations throughout the day. Possible complications of hypophenylalaninaemia and potential preventive treatment strategies are discussed. Further studies are needed to investigate the longer‐term clinical and biochemical consequences of phenylalanine supplementation.