Exhibit 31.1
CERTIFICATION PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002
I, Emil D. Kakkis, certify that:
1. | I have reviewed this Quarterly Report on Form 10-Q/A of Ultragenyx Pharmaceutical Inc.; and |
2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report. |
| /s/ Emil D. Kakkis | |
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| Emil D. Kakkis, M.D., Ph.D. |
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| President and Chief Executive Officer |
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| (Principal Executive Officer) |