OBJECTIVETo study the mutations in exons 3, 6, 7, 11 and 12 of the phenylalanine hydroxylase gene (PAH) in Shanxi population.

METHODSThe mutations in exons 3, 6, 7, 11 and 12 and flanking sequences of PAH gene were detected by PCR-DNA sequencing, in 59 patients with phynelketonuria(PKU) and 100 healthy children from Shanxi province.

RESULTSBy sequence analysis, three single nucleotide polymorphism (SNP) Q232Q (CAA>CAG), V245V (GTG>GTA) and L385L (CTG>CTC) were detected in both the patients and healthy children, with the frequencies of nt 696, 735 and 1155 of the PAH cDNA up to 96.2%, 76.1% and 7.6% in patients respectively, and 97.0%, 77.3% and 8.3% respectively in the healthy controls. In addition, 72 different mutations accounting for 61.0% of mutant alleles were identified in the patients only. In exon 3, R111X, H64>TfsX9 and S70 del were found accounting for 5.1%, 0.8% and 0.8%; EX6-96A>G in exon 6 was found accounting for 10.2%. In exon 7, R243Q was the highest incidence accounting for 12.7%, followed by Ivs7+2 T>A(5.1%) and T278I(2.5%); the lowest incidences were G247V, R252Q, L255S, R261Q and E280K accounting for 0.8 %, respectively. In exon 11, Y356X (5.9%) and V399V (5.1%) were found; in exon 12, R413P and A434D were found accounting for 5.9% and 2.5%. In total, 9 missense mutations, 3 splice site mutations, 2 nonsense mutations and 2 deletions were included in 16 kinds of different mutations.

CONCLUSIONThe mutation characteristics and distribution in exons 3, 6, 7, 11 and 12 of the PAH gene have been identified, and it suggested that the EX6-96A>G and R243Q were the hot spots of PAH gene mutations in Shanxi PKU population.