Phenylketonuria: detection of a frequent haplotype 4 allele mutation

Summary By sequence analysis of 94 phenylketonuria (PKU) alleles using polymerase chain reaction (PCR) based techniques, we identified a G to A transition in exon 5 of the human phenylalanine hydroxylase gene. This base substitution predicts an Arg¹⁵⁸Glu¹⁵⁸ amino acid exchange and is strongly associated with the mutant haplotype 4 PKU allele.