X0306 4 2020-02-11 0 0001681087 AVROBIO, Inc. AVRO 0001741849 MACKAY GEOFFREY C/O AVROBIO, INC. 1 KENDALL SQ. BLDG 300, STE 201 CAMBRIDGE MA 02139 1 1 0 0 See Remarks Common Stock 2020-02-11 4 S 0 44596 27.3563 D 364927 D Common Stock 2020-02-11 4 S 0 18404 28.0971 D 346523 D Common Stock 72604 I By son of reporting person Common Stock 72604 I By daughter of reporting person The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.00 to $27.995, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.00 to $28.35, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. President and Chief Executive Officer /s/ Steven Avruch, as Attorney-in-Fact 2020-02-11