( Luc Michiels 1 Baudoui...)Identification of Disease Causing Mutations in Phenylketonuria by Denaturing Gradient Gel Electrophoresis Using the DCode System

Luc Michiels¹, Baudouin Franois^{1, 2}, and Jef Raus^{1, 2}, 1 Dr. L. Willems-Instituut and 2 Limburgs Universitair Centrum, Universitaire Campus, B-3590 Diepenbeek, Belgium

Introduction
Phenylketonuria (PKU) is a hereditary disease that gives rise to elevated blood levels of phenylalanine. The disease most frequently is caused by mutations in the phenylalanine hydroxylase gene. This gene is situated at the human chromosomal locus 12q22-q24.1 and encodes a hepatic enzyme that hydroxylates phenylalanine (PAH; phenylalanine 4-monooxygenase, EC 1.14.16.1). The large variety of mutations described in this gene results in a broad range of plasma phenylalanine concentrations associated with phenotypic differences ranging from the severest form of PKU to the mildest hyperphenylalaninaemia. PKU is autosomal recessively inherited, carriers therefore are phenotypically normal, with no pronounced elevated phenylalanine or tyrosine blood levels. The need for a reliable method to identify persons carrying PAH mutations is evident. To identify mutations in each of the 13 exons of the PAH gene, Guldberg and coworkers (1993) reported a method based on DGGE.¹ For the rapid screening of PKU patients and their relatives for mutations in the PAH exons and intron/exon boundaries we further refined this method by using multiplex PCR* amplifications combined with Multiplex Denaturing Gradient Gel electrophoresis analysis (Michiels et al., 1996).³

Methods
MULTIPLEX PCR AMPLIFICATION OF PAH DNA
Genomic DNA of PKU patients was prepared from dried blood spots on Guthrie cards using the Chelex<sup>'"/>

Source:</sup>