Screening and mutation analysis of hyperphenylalaninemia in newborns from Xiamen, China

In this study, we evaluated the incidence and genetic characteristics of hyperphenylalaninemia (HPA) in Xiamen, China. We analyzed the newborn screening data of HPA, obtained using a fluorometric method and tandem mass spectrometry (MS/MS), from 2013 to 2017. The suspected positive samples were further diagnosed using MassArray technology, multiplex ligation-dependent probe amplification (MLPA), and Sanger sequencing. A total of 418,831 newborns were screened, of whom 19 were diagnosed as HPA patients, with an incidence of 1:22,044. Of these HPA patients, 15 tested positive for phenylketonuria (PKU, 1:27922), and 4 tested positive for tetrahydrobiopterin deficiency (BH4D, 1:104,708). A total of 17 mutations were identified among 38 alleles in the 19 patients, with a detection rate of 94.74%, including 13 PAH and 4 PTS mutations. Among these, the c.721C>T, c.728G>A, c.1197A>T, c.611A>G and c.331C>T mutations, and the c.259C>T and c.155A>G mutations were the most prevalent PAH and PTS mutations in Xiamen, respectively. Therefore, this study systematically demonstrated the incidence and mutation spectrum of HPA in Xiamen. This information would contribute to genetic counseling, prenatal diagnosis, and management of HPA patients. Moreover, combining MS/MS technology with molecular genetic diagnosis is an effective strategy for future newborn HPA screening in Xiamen.