Screening for genetic mutations in hyperphenylalaninemia using Ion Torrent PGM sequencing

Abstract

To establish a hyperphenylalaninemia related genes screening method using Ion Torrent Personal Genome Machine (PGM) for early detection and differential diagnosis of hyperphenylalaninemia (HPA). Three children with known HPA mutations and a healthy control were used for setting up the method. Ten children with HPA with known mutations were recruited for validating the method. Ion Ampliseq PCR was used to amplify the 5' and 3' untranslated region, coding sequence, and flanking introns of PAH, GCH1, PTS, QDPR, and PCBD1 genes. After the enrichment with the Ion OneTouch system, the products were sequenced by PGM. Data from the PGM were processed with Torrent Suite v2.2 software package. All variations were confirmed by Sanger sequencing. For the 4 samples, the PGM output was 94.22 Mb, with approximately 99.5% of reads mapping to the target regions. Among these samples, we detected 74 variations (28 positions) including 6 known mutations. Compared with database and results of Sanger sequencing, 55 (18 positions) polymorphisms and 13 (4 positions) false positive calls were confirmed. For the 10 samples, all the known mutations were successfully identified. Ion Torrent PGM sequencing is suitable for screening genetic mutation underlying HPA from the perspective of metabolic pathways, which can meet the clinical demand for individualized diagnosis and treatment.