Abstract: Objective  To analyze the screening of neonatal hypermethionemia in Shijiazhuang City retrospectively, and to detect the incidence and MAT1A gene mutation. 
Methods  A total of 149 094 cases neonates born in Shijiazhuang were screened by tandem mass spectrometry-non-derivative method to detect the methionine concentration in dried blood spots of filter paper. Next-generation sequencing technology was used to detect positive children, and the MAT1A gene mutations were verified by Sanger sequencing. 
Results  Among 149 094 neonates, 13 were confirmed positive, with an incidence of 1/11 469. All 13 patients had isolated hypermethioninemia, except for 1 patient with elevated homocysteine. The mutations in the MAT1A gene were identified in 9 children with simple hypermethionine, including 7 heterozygous mutations, 1 compound heterozygous mutation, and 1 loss of heterozygosis. Nine types of point mutations were found by gene sequencing, including 4 types that had been reported, namely, c.791G＞A, c.769G＞A, c.1070C＞T and c.874C＞T, and 5 types that had not been reported, namely, c.1086-3C＞G, c.712G＞A, c.188G＞T, c.757G＞A and c.178T＞C. 
Conclusion  The incidence of hypermethioninemia in neonates in Shijiazhuang is 1/11 469; 5 unreported gene mutations were found by gene sequencing, which enriched the database. 

Key words: eonatal disease screening, tandem mass spectrometry, hypermethioninemia, MAT1A gene