title: A case of tetrahydrobiopterin deficiency due to a defective synthesis of dihydrobiopterin.
mesh_terms: D001708:Biopterins / Q000031:analogs & derivatives / Q000096:biosynthesis* / Q000172:deficiency*; D006801:Humans; D007223:Infant; D008297:Male; D010649:Phenylalanine / Q000097:blood; D011621:Pteridines / Q000096:biosynthesis* / Q000172:deficiency*
chemical_list: D011621:Pteridines; D001708:Biopterins; D010649:Phenylalanine; C017226:7,8-dihydrobiopterin; C003402:sapropterin