Probably mediates the removal of pyrophosphate from dihydroneopterin triphosphate (DHNTP), a possible step in the pterin branch of the folate synthesis pathway. Cofactor biosynthesis; tetrahydrofolate biosynthesis; 2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine diphosphate from 7,8-dihydroneopterin triphosphate: step 1/4. Monomer. Belongs to the Nudix hydrolase family.