Molecular characterization of 6-pyruvoyl-tetrahydropterin synthase deficiency in Japanese patients.
We identified three mutations in four Japanese patients with central type 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency. One missense mutation was a C-to-T transition, resulting in the substitution of Pro by Ser at codon 87 (P87S) in exon 5. Another missense mutation was a G-to-A transition, resulting in the substitution of Asp by Asn at codon 96 (D96N) in exon 5. A splicing mutation was found by skipping of exon 4 on PTPS mRNA analysis, and a G-to-A transition at the third base of codon 81 (E81E) and at the terminal base in exon 4 were detected on genomic PTPS DNA analysis. The E81E mutation affected the splice donor site of exon 4 and caused the splicing error. In COS cell expression analysis, the P87S and D96N mutant constructs revealed, respectively, 52% and 10% of wild-type activity. Patients with P87S/P87S (52%/52% in-vitro PTPS activity) exhibited 0.11 and 0 microU/g hemoglobin [Hb] in erythrocyte PTPS activity (wild-type control: 11-29 microU/gHb) erythrocyte PTPS activity, and the patient with P87S/D96N mutations (52%/10%) had 0.97 microU/gHb in PTPS erythrocyte activity. The PTPS erythrocyte activity did not coincide with the in-vitro PTPS activity based on patient genotype.
D000592:Amino Acid Metabolism, Inborn Errors / Q000235:genetics*; D044466:Asian People / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007564:Japan; D008297:Male; D020125:Mutation, Missense; D010649:Phenylalanine / Q000097:blood; D019761:Phosphorus-Oxygen Lyases / Q000172:deficiency* / Q000235:genetics*; D017422:Sequence Analysis, DNA