Abstract:

Objective To investigate the screening, clinical manifestations, genetic variants and long-term follow-up results of 6-pyruvoyltetrahydropterin synthase deficiency (PTPSD) in Qingdao. Methods Two hundred and fifty-one children with hyperphenylalaninemia (HPA) in Qingdao Women and Children's Hospital from November 1998 to December 2021 were included, and urinary pterin profile test, erythrocyte dihydropteroate reductase activity test, tetrahydrobiopterin (BH4) loading test, and genetic test were performed to confirm the diagnosis of PTPSD. The incidence, gene mutations and long-term follow-up of PTPSD were analyzed. Results Twenty-six children were diagnosed as tetrahydrobioptenin deficiency (BH4D), all PTPSD, and the incidence of PTPSD among newborns in Qingdao was 12.7 per million. 19 children (from 17 families) underwent genetic testing, and 10 variants were detected among 34 alleles of PTS, with the higher frequency of variants being c.259C>T (29.4%, 10/34), and the rest were c.286G>A (14.7%, 5/34), c.272A>G (14.7%, 5/34), c.84-291A>G (8.8%, 3/34), c.166G>A (8.8%, 3/34), c.276T>A (8.8%, 3/34 ), and the variant sites were mainly concentrated in exon 5 (67.6%, 23/34). Among them, c.200C>T, c.259C>T and c.286G>A may be associated with severe PTPSD. Conclusion The incidence of PTPSD in Qingdao is 12.7/ million in 1996-2021, and the hotspot variants of PTS gene are c.259C>T, c.286G>A, c.272A>G. Establishment of a complete integrated management system of newborn disease screening-diagnosis-treatment-long-term follow-up-assistance is a powerful measure to achieve a tertiary prevention of birth defects and reduce the occurrence of disabled children.

Key words: hyperphenylalaninemia, tetrahydrobiopterin deficiency, 6-pyruvyl tetrahydrotrexate synthetase deficiency, gene variation