Predicted to enable 6,7-dihydropteridine reductase activity; NADH binding activity; and NADPH binding activity. Predicted to be involved in L-phenylalanine catabolic process and tetrahydrobiopterin biosynthetic process. Predicted to be active in cytoplasm. Is expressed in several structures, including adult head; adult heart; embryonic/larval midgut; embryonic/larval midgut primordium; and somatic trunk mesoderm derivative. Human ortholog(s) of this gene implicated in BH4-deficient hyperphenylalaninemia C and phenylketonuria. Orthologous to human QDPR (quinoid dihydropteridine reductase).