Plasma phenylalanine and tyrosine levels revisited in heterozygotes for hyperphenylalaninaemia.
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.
Saraiva
J M
JM
Paediatric Hospital, Coimbra, Portugal.
Seakins
J W
JW
Smith
I
I
D000592:Amino Acid Metabolism, Inborn Errors / Q000097:blood* / Q000235:genetics; D001499:Bayes Theorem; D005260:Female; D006579:Heterozygote; D006801:Humans; D008297:Male; D010649:Phenylalanine / Q000097:blood*; D012307:Risk Factors; D014443:Tyrosine / Q000097:blood*
D014443:Tyrosine; D010649:Phenylalanine