SCREENING FOR TETRAHYDROBIOPTERIN DEFICIENCY AMONG HYPERPHENYLALANINEMIA IN SOUTHERN CHINESE

Ye J, Gu XF, Liu XQ, Huang XD

Xin Hua Hospital, Shanghai Second Medical University and Shanghai Institute for Pediatric Research, Shanghai, China

 

Objective: To find the incidence of tetrahydrobiopterin deficiency (BH4D) among patients with hyperphenylalaninemia(HPA) in Southern Chinese and evaluate the clinical outcome and gene mutations in BH4D

Methods: Analysis of urinary neopterin (N) and biopterin (B) was done in 87 patients with HPA by HPLC. Further combined loading test with phenylalanine and tetrahydrobiopterin were performed in suspected cases with abnormal urinary pterin profiles. Gene mutation analysis was performed for BH4D patients.

Results: Eleven patients were diagnosed as having BH4 deficiency caused by 6-Pyruvoyl tetrahydropterin synthase (PTPS) deficiency. The six PTPS- deficient patients were found in 50 PKU diagnosed by neonatal screening in Southern Chinese, with the incidence of BH4 deficiency of 12%. The Phe levels were decreased to normal 4-6h after BH4 administration in 4 of 11 patients. Four different mutations (P87S, N52S, D96N and G144R) in PTPS gene were detected from 5 families. The five PTPS-deficient patients had satisfactory physical and mental development after treatment with synthetic BH4, neurotransmitter precursors Dopa and 5-hydroxytryptophan.

Conclusions: Our results emphasize that screening for BH4 deficiency should be carried out in all patients with hyperphenylalaninemia in order to minimize the misdiagnoses.

 

 
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