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Effects of untreated maternal phenylketonuria and hyperphenylalaninemia on the fetus

H L Levy, S E Waisbren

    The New England Journal of Medicine
    |November 24, 1983
    PubMed

    Insights

    Maternal phenylketonuria significantly impacts offspring IQ and development. High maternal phenylalanine levels above 1100 mumol/L are linked to mental retardation and microcephaly in children.

    Area of Science:

    • Medical Genetics
    • Developmental Pediatrics
    • Metabolic Disorders

    Background:

    • Maternal phenylketonuria (PKU) and hyperphenylalaninemia are metabolic conditions.
    • Untreated maternal PKU poses risks to fetal development.
    • The precise impact of varying phenylalanine levels on offspring is a critical concern.

    Purpose of the Study:

    • To investigate the effects of maternal phenylketonuria and hyperphenylalaninemia on offspring development.
    • To establish correlations between maternal phenylalanine levels and offspring cognitive outcomes.
    • To determine thresholds for adverse developmental effects in offspring.

    Main Methods:

    • Studied 53 offspring from 22 mothers with untreated phenylketonuria or hyperphenylalaninemia.
    • Analyzed offspring IQ and presence of microcephaly.
    • Correlated offspring outcomes with maternal IQ and blood phenylalanine levels.

    Main Results:

    • Offspring IQ strongly correlated with maternal IQ (r=0.83) and maternal phenylalanine levels (r=0.82).
    • Mental retardation in offspring occurred when maternal phenylalanine exceeded 1100 mumol/L.
    • Microcephaly in offspring was consistently observed when maternal phenylalanine exceeded 1200 mumol/L.
    • Congenital anomalies were infrequent.

    Conclusions:

    • Severe maternal phenylketonuria (phenylalanine >1100 mumol/L) significantly affects offspring cognition.
    • The impact of mild hyperphenylalaninemia on offspring may have been previously overestimated.
    • Maternal phenylalanine control is crucial for preventing developmental deficits in offspring.

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