Article

Mutation analysis of PAH gene and characterization of a recurrent deletion mutation in Korean patients with phenylketonuria.

Department of Laboratory Medicine and Genetics, Soonchunhyang University Bucheon Hospital, Soonchunhyang Univerisity College of Medicine, Bucheon 420-767, Korea.
Experimental and Molecular Medicine (impact factor: 2.48). 11/2008; 40(5):533-40. pp.533-40
Source: PubMed

ABSTRACT Phenylketonuria (PKU; MIM 261600) is an autosomal recessive metabolic disorder caused by a deficiency of phenylalanine hydroxylase (PAH; EC 1.14.16.1). Point mutations in the PAH gene are known to cause PKU in various ethnic groups, and large deletions or duplications account for up to 3% of the PAH mutations in some ethnic groups. However, a previous study could not identify approximately 14% of the mutant alleles by sequence analysis in Korean patients with PKU, which suggests that large deletions or duplication might be frequent causes of PKU in Koreans. To test this hypothesis, we performed multiplex ligation-dependent probe amplification (MLPA) for the identification of uncharacterized mutant alleles after PAH sequence analysis of 33 unrelated Korean patients with PKU. Bi-directional sequencing of the PAH exons and flanking intronic regions revealed 27 different mutations, including four novel mutations (two missense and two deletion mutations), comprising 57/66 (86%) mutant alleles. MLPA identified a large deletion that encompassed exons 5 and 6 in four patients, another large deletion that extended from exon 4 to exon 7 in one patient, and a duplication of exon 4 in one patient. Chromosomal walking characterized the deletion breakpoint of the most common large deletion that involved exons 5 and 6 (c.456_706+138del). The present study shows that the allelic frequency of exon deletion or duplication is 9% (6/66) in Korean PKU patients, which suggests that these mutations may be frequent causes of PKU in Korean subjects.

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Keywords

27 different mutations
 
33 unrelated Korean patients
 
autosomal recessive metabolic disorder
 
Bi-directional sequencing
 
common large deletion
 
deletion breakpoint
 
duplications account
 
encompassed exons 5
 
ethnic groups
 
exon 4
 
exon 7
 
exon deletion
 
flanking intronic regions
 
involved exons 5
 
Korean patients
 
Korean PKU patients
 
large deletion
 
large deletions
 
multiplex ligation-dependent probe amplification
 
various ethnic groups
 

Yong-Wha Lee