The , a.k.a. mucopolysaccharidosis type VII or MPS VII, the agency said Wednesday.
MPS VII is a lysosomal storage disorder in which beta-glucuronidase is deficient. The novel enzyme therapy, to be sold by Ultragenyx Pharmaceutical, is a recombinant version of the missing enzyme.
Data supporting the approval came from a clinical trial and also individual patients receiving the product through the FDA's expanded access program -- 23 patients in all. Patients receiving the agent showed an 18-meter improvement in 6-minute walk distance after 24 weeks relative to a placebo group. Longer treatment resulted in additional gains or stabilization.
"Overall, the results observed would not have been anticipated in the absence of treatment," the FDA said.