2.1.4 Sequencing of PCR products
PCR products were sent to Biotechnology (Shanghai) Co., Ltd. for sequencing. Compared with the PAH genomic DNA sequence (GI: 209364518) in GenBank, the naming of mutations followed the principles of the PAH database (http://www.pahdb.mcgill.ca/). Novel mutations were identified by referring to the Human Gene Mutation Database (http://www.hgmd.org) and related literature. A mutation was considered to be new after screening the exons of 50 unrelated individuals to exclude it as a polymorphic site.