X0206 3 2017-10-09 1 0001527599 SYNLOGIC, INC. SYBX 0001563623 Gengos Andrew C/O SYNLOGIC, INC. 200 SIDNEY STREET, SUITE 320 CAMBRIDGE MA 02139 0 1 0 0 See Remarks Chief Operating Officer and Head of Corporate Development /s/ William J. Bussiere, Jr., Attorney-in-fact 2017-10-10