Exhibit 23.1
CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
We consent to the use in this Registration Statement onForm S-1 of our report dated June 28, 2019 relating to the financial statements of IGM Biosciences, Inc. appearing in the Prospectus, which is part of this Registration Statement.
We also consent to the reference to us under the heading “Experts” in such Prospectus.
/s/ Deloitte & Touche LLP
San Francisco, California
August 19, 2019