Exhibit 23.1
CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
We consent to the incorporation by reference in this Registration Statement on FormS-8 of our report dated March 26, 2020 relating to the financial statements of IGM Biosciences, Inc. appearing in the Annual Report on Form10-K of IGM Biosciences, Inc. for the year ended December 31, 2019.
/s/ Deloitte & Touche LLP
San Francisco, California
March 26, 2020