X0306 4 2020-09-11 0 0001274737 EXAGEN INC. XGN 0001230641 TULLIS JAMES L L 11770 US HIGHWAY ONE, SUITE 503 PALM BEACH GARDENS FL 33408 1 0 1 0 Common Stock 2020-09-11 4 S 0 15000 12.40 D 1585275 I See footnote. Common Stock 38745 D Common Stock 1431 I By Spouse Common Stock 4537 I By Trust The shares reported on this form are held of record by Tullis-Dickerson Capital Focus III, L.P. ("Tullis"), Tullis Growth Fund, L.P. ("Tullis Growth") and Tullis Growth Fund II, L.P. ("Tullis Growth II"). Tullis-Dickerson Partners III, LLC ("Tullis Partners") is the general partner of Tullis and may be deemed to beneficially own the securities held by Tullis. Tullis Growth Partners, LLC and Tullis Growth Partners II, LLC are the general partners of Tullis Growth and Tullis Growth II, respectively, and may be deemed to beneficially own the securities held by Tullis Growth and Tullis Growth II. James L.L. Tullis is a Principal of each of the foregoing entities and may be deemed to possess voting and investment control over, and may be deemed to have an indirect beneficial ownership with respect to, the shares held by Tullis, Tullis Growth and Tullis Growth II. /s/ John L. Tullis as Attorney-in-Fact for James L.L. Tullis 2020-09-14