Overview Response to Phenylketonuria to Tetrahydrobiopterin (BH4) Status: Terminated Trial end date: 2015-01-01 Target enrollment: Participant gender: Summary The purpose of this study is to determine whether tetrahydrobiopterin (BH4)is effective in treating patients with PKU. Phase: Phase 1 Details Lead Sponsor: FDA Office of Orphan Products DevelopmentThe University of Texas Medical Branch, Galveston