Phenylalanine hydroxylase deficiency
Classic phenylketonuria (PKU)
Variant PKU
Non-PKU hyperphenylalaninemia (non-PKU HPA)
In non-PKU HPA, there is elevation of phenylalanine (phe) in the blood but not enough to qualify as PKU or variant PKU. Non-PKU HPA is associated with the least risk of intellectual damage. Variant PKU is intermediate between PKU and non-PKU HPA.
The decision as to whether an individual needs to be on a low-phenylalanine diet is based on their blood level of phenylalanine (phe), rather on the precise condition causing the elevated phe, because phe is toxic to the brain.
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The inherited inability to metabolize (process) the essential amino acid phenylalanine due to complete or near-complete deficiency of the enzyme phenylalanine hydroxylase. Newborns are screened for phenylketonuria (PKU) by a blood test, usually with the Guthrie card bloodspot obtained from a heelprick. Treatment is with a special diet low in phenylalanine. The goal is to […]
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