primarily evaluated by the 6-minute walking test (6MWT) and compared to placebo treatment in ten participants who could perform the test. The 6MWT measured the distance a patient could walk on a flat surface in 6 minutes. An additional follow-up using 6MWT was done for up to 120 weeks. The application for vestronidase alfa was granted fast track designation, orphan drug designation, and a rare pediatric disease priority review voucher. This was the twelfth rare pediatric disease priority review voucher issued. The U.S. Food and Drug Administration (FDA) granted approval of Mepsevii to Ultragenyx Pharmaceutical, Inc, and required the manufacturer to conduct a post-marketing study to evaluate the long-term safety of the product. References External links Orphan drugs Recombinant proteins