Identification of Mutations Causing 6-Pyruvoyl- Tetrahydrobiopterin Synthase Deficiency in Polish Patients With Variant Hyperphenylalaninemia.

Background: 6-Pyruvoyl-tetrahydrobiopterin synthase (PTPS) is required for biosynthesis of tetrahydrobiopterin, the cofactor of various enzymes including the hepatic phenylalanine hydroxylase. Mutations in the PTS gene result in a variant type of hyperphenylalaninemia, requiring cofactor replacement therapy for treatment. Methods and Results: Four Polish patients with PTPS deficiency were screened for mutations in the PTS gene. Three novel mutations E35G, N36K, and F100V were identified. In one patient, a known mutation D136V was identified in both PTS alleles. Conclusions: Mutation D136V present in both alleles was proposed to be connected with a mild form of PTPS deficiency. The other three mutations were found in heterozygous patients with a central type of PTPS deficiency. D136V mutation is a common mutation in the Polish population.