Background Phenylketonuria (PKU) is a genetic metabolic disease with a relatively higher incidence, but only a few studies about the prenatal diagnosis of PKU have been reported so far in China. The aim of this study was to characterize the spectrum of mutations in PAH gene in PKU probands and the prenatal diagnosis of PKU in north China.
Methods A total of 157 families in which PKU patients had been diagnosed were included in the study. The 13 exons and their flanking sequences of PAH gene were amplified by PCR and sequenced in the probands. If none or only one mutant allele was found in the probands, the sample was subjected to MLPA for large deletions/duplication detection in PAH gene. Prenatal diagnosis was performed for pregnant women in these families.
Results Pathogenic mutation in PAH was found in 2 alleles in 148 probands and in one allele in 7 probands, and the mutation was not detected in 2 probands. There were 289 point mutants, 10 frame-shift mutations and 4 large deletions with a total of 80 kinds of mutations. The most prevalent mutations were R243Q (17.2%), EX6-96A>G (8.6%) and V399V (8.0%). We also found a novel mutation of 163_164insATAT. Prenatal diagnosis of 95 families found 21 healthy fetus (20.4%), 52 carriers (50.5%) and 30 patients (29.1%), and the accuracy of prenatal diagnosis was confirmed after birth of the fetuses.
Conclusion We present here a spectrum of mutations in PAH gene in PKU patients in north China. Prenatal diagnosis for PKU is useful for PKU families to prevent birth of another PKU case.