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Plasma phenylalanine and tyrosine levels revisited in heterozygotes for hyperphenylalaninaemia

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Journal of Inherited Metabolic Disease

Summary

We examined the value of the fasting plasma phenylalanine/tyrosine ratio obtained in an ordinary clinical setting for assessing the probability of being a heterozygote for hyperphenylalaninaemia. This biochemical test was found to be of little value in those with a high (66%) prior risk of heterozygosity, because it could not reduce the risk below 12%. However, in a population with a prior risk of only 2%, it discriminates the 3% with a 19% risk from the 97% with a risk of 1.5% or less. This simple method could usefully be applied to such a population, in order to select those at higher risk for further investigation using molecular genetics.

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Authors and Affiliations

  1. Paediatric Hospital, 3000, Coimbra, Portugal

    J. M. Saraiva

  2. Department of Child Health, Institute of Child Health, 30 Guilford Street, WC1N 1EH, London, UK

    J. W. T. Seakins & I. Smith

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  1. J. M. Saraiva
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  2. J. W. T. Seakins
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  3. I. Smith
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Saraiva, J.M., Seakins, J.W.T. & Smith, I. Plasma phenylalanine and tyrosine levels revisited in heterozygotes for hyperphenylalaninaemia. J Inherit Metab Dis 16, 105–109 (1993). https://doi.org/10.1007/BF00711323

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  • DOI: https://doi.org/10.1007/BF00711323

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