Rhythm Pharmaceuticals (RYTM) S-1 IPO registration

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Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

        We consent to the reference to our firm under the caption "Experts" and to the use of our report dated May 23, 2017, in the Registration Statement (Form S-1) and related Prospectus of Rhythm Pharmaceuticals, Inc. for the registration of shares of its common stock.

/s/ Ernst & Young LLP

Boston, Massachusetts
September 5, 2017

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Exhibit 23.1