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The presence of abnormally high blood levels of phenylalanine, which may be associated with elevated tyrosine levels, in newborn infants (premature and full-term), associated with the heterozygous state of phenylketonuria, maternal phenylketonuria, or transient deficiency of phenylalanine hydroxylase or p-hydroxyphenylpyruvic acid oxidase.
1. any of several inherited defects in the hydroxylation of phenylalanine causing it to be accumulated and excreted; some are benign while others cause phenylketonuria, at least one type of which is unresponsive to treatment and rapidly fatal.
2. excess of phenylalanine in the blood.
Any of several genetic disorders, including phenylketonuria, that are characterized by abnormally high levels of phenylalanine in the blood.
Etymology: Gk, hyper + (phenylalanine), haima, blood
an abnormally high concentration of phenylalanine in the blood. This symptom may be the result of one of several defects in the metabolic process of breaking down phenylalanine. See also phenylketonuria.
hyperphenylalaninemiaA group of 8 different congenital enzymopathies characterized by an accumulation of phenylalanine and related metabolites–eg, phenylpyruvate, phenyllactate, phenylacetate, phenylacetylglutamine, a deficiency of T4, T3, melanin and other proteins; the most common or 'classic' phenylketonuria–PKU or hyperphenylalaninemia, type 1 is an AR condition characterized by a deficiency in phenylalanine hydroxylase, which if not recognized early–urine has a 'mousy' odor—and treated by restricting dietary phenylalanine, results in tremors, seizures, eczema, hyperactivity, and hypopigmentation and IQ of < 50; other hyperphenylalaninemia types–eg, types 2, 3 and 7, are relatively benign
The presence of abnormally high blood levels of phenylalanine in newborn infants associated with phenylketonuria, maternal phenylketonuria, or transient deficiency of phenylalanine hydroxylase or p-hydroxyphenylpyruvic acid oxidase.