Relative reliability of three different discriminant analysis methods for detecting PKU gene carriers.

A previously derived discriminant function for detecting classical PKU gene carriers without a priori pedigree probability was reevaluated using a large sample size. The test involves fluorometric measurement of fasting phenylalanine and tyrosine plasma levels. Among 75 controls and 45 known carriers, 95% could be classified as to their carrier status with greater than 98% accuracy. The accuracy of our method in classifying our population compared favorably to that of two other discriminant analysis methods requiring a priori probability.