Phenylalanine hydroxylase gene: novel missense mutation in exon 7 causing severe phenylketonuria.
By direct sequence analysis of 94 mutant phenylalanine hydroxylase alleles using polymerase chain reaction-based techniques, we identified a C to T transition in exon 7 of the human phenylalanine hydroxylase gene that is associated with RFLP haplotypes 1 and 4. A leucine for proline substitution at position 281 can be predicted from the nucleotide sequence of the mutant codon. Expression analysis in cultured mammalian cells after site-directed mutagenesis proved that the base substitution is a disease causing gene lesion. Dot-blot hybridization analysis using allele-specific oligonucleotides revealed that 25% of all mutant haplotype 1 alleles in the German population bear this mutation. In addition, this mutation could be detected on one mutant haplotype 4 allele. The fact that this mutation is associated with only 25% of all mutant haplotype 1 alleles suggests that multiple mutations may be associated with this haplotype. The occurrence of several different mutations would be in agreement with the clinical heterogeneity observed in the group of patients whose PKU alleles belong to haplotype 1.
Dworniczak
B
B
Institut für Humangenetik der Universität, Münster, Federal Republic of Germany.
Grudda
K
K
Stümper
J
J
Bartholomé
K
K
Aulehla-Scholz
C
C
Horst
J
J
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D005091:Exons; D015870:Gene Expression; D005796:Genes; D006239:Haplotypes; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010651:Phenylalanine Hydroxylase / Q000235:genetics* / Q000378:metabolism; D010661:Phenylketonurias / Q000201:enzymology / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length
D010651:Phenylalanine Hydroxylase