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Treatment with KRN23 induces a sustained increase in serum phosphorus and increases in bone remodeling markers

Novato, CA— June 24, 2014 — Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE), a biopharmaceutical company focused on the development of novel products for rare and ultra-rare diseases, today announced the presentation of results from a multiple-dose study, conducted by Kyowa Hakko Kirin Pharma, Inc (KKP), of the investigational anti-FGF23 monoclonal antibody KRN23 (UX023) in adult patients with X-linked hypophosphatemia (XLH). XLH is an inherited metabolic bone disease characterized by short stature, skeletal deformities, bone pain, fractures, and muscle weakness. The data was presented at the 2014 ICE/ENDO joint meeting of The Endocrine Society and The International Congress of Endocrinology in Chicago.