Ultragenyx Analyst Day Presentation

Near-term key clinical catalysts PROGRAM UX143 Osteogenesis Imperfecta GTX-102 Angelman Syndrome UX701 Wilson Disease DTX401 GSDla OBJECTIVE Complete enrollment of Phase 3 Orbit study Complete enrollment of Phase 3 Cosmic Further Phase 2 data update LPI for Expansion Cohorts Phase 1/2 Expansion data End of Phase 2 Discussion with FDA Stage 1 enrollment completion Stage 1 safety and initial efficacy data Initiation of Stage 2 Phase 3 data Timing 1Q 2024 1H 2024 2H 2024 ✓ 1H 2024 Mid-2024 ✓ Mid-2024 2H 2024 1H 2024 DTX301 Phase 3 enrollment completion 1H 2024 OTC deficiency ultragenyx 17 Confidential and Proprietary

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