[Mutation analysis of phenylalanine hydroxylase gene in 55 patients with phenylketonuria from Hebei province].

OBJECTIVE

To identify the pathogenic mutations of phenylalanine hydroxylase gene (PAH) in patients with phenylketonuria (PKU) from Hebei Province.

METHODS

Genomic DNA was extracted from 55 unrelated PKU patients from September 2007 to July 2009. All PAH exons and exon-intron junctions were amplified by polymerase chain reaction (PCR) and sequenced. Multiplex ligation-dependent probe amplifications (MLPA) was performed to detect the deletions or duplications of PAH. Gap-PCR was used to determine the breakpoints of large deletions.

RESULTS

Among them, 108 mutant alleles (98.2%) were found. All PAH exons with the exceptions of exons 9 and 13 were affected. A total of 41 different mutations were detected, including missense (n = 24), nonsense (n = 7), splicing (n = 7), small deletion (n = 1) and large deletion (n = 2). Among them, 4 missense mutations (p.Pro147Leu, p.Gly289Arg, p.Phe392Ser, p.Ile421Thr) and 2 large deletions (-4163_-406del and -1932_+3402del) were novel. The most common mutations were p.Arg243Gln (12.7%), c.611A > G (11.8%) and c.1197A > T (9.1%).

CONCLUSION

The mutations of PKU patients with from Hebei Province are scattered throughout the PAH gene. Most of them are of single nucleotide substitutions, but large deletions are not rare.