X0306 4 2018-06-25 0 0001681087 AVROBIO, Inc. AVRO 0001717728 SVLSF VI, LLC ONE BOSTON PLACE, SUITE 3900 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 0001642251 SV Life Sciences Fund VI, L.P. ONE BOSTON PLACE, SUITE 3900 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 0001667605 SV Life Sciences Fund VI Strategic Partners, L.P. ONE BOSTON PLACE, SUITE 3900 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 0001717730 SV Life Sciences Fund VI (GP), L.P. ONE BOSTON PLACE, SUITE 3900 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 Common Stock 2018-06-25 4 C 0 2207843 A 2207843 I See Footnote Common Stock 2018-06-25 4 C 0 75591 A 75591 I See Footnote Common Stock 2018-06-25 4 C 0 437611 A 2645454 I See Footnote Common Stock 2018-06-25 4 C 0 14982 A 90573 I See Footnote Series A Preferred Stock 2018-06-25 4 C 0 9122809 0.00 D Common Stock 2207843 0 I See footnote Series A Preferred Stock 2018-06-25 4 C 0 312341 0.00 D Common Stock 75591 0 I See footnote Series B Preferred Stock 2018-06-25 4 C 0 1808211 0.00 D Common Stock 437611 0 I See footnote Series B Preferred Stock 2018-06-25 4 C 0 61908 0.00 D Common Stock 14982 0 I See footnote Represents the total number of shares of Common Stock received by SV Life Sciences Fund VI, L.P. ("SV Life LP") upon the conversion of the Issuer's Series A Preferred Stock in connection with the closing of the Issuer's initial public offering. The shares are held directly by SV Life LP. SV Health Investors, LLC is the Manager of SV Life LP. SV Life Sciences Fund VI (GP), L.P., ("SV Fund VI GP") is the general partner of SV Life LP. The general partner of SV Fund VI GP is SVLSF VI, LLC. The members of the investment committee of SVLSF VI, LLC are Kate Bingham, Thomas Flynn, James Garvey, Eugene D. Hill, III, Paul LaViolette, and Michael Ross. Each of SV Fund VI GP, SVLSF VI, LLC and the SVLSF VI, LLC investment committee disclaims beneficial ownership of the shares owned directly by SV Life LP, except to the extent of any pecuniary interest therein. Represents the total number of shares of Common Stock received by SV Life Sciences Fund VI Strategic Partners, L.P. ("SV Life SP LP") upon the conversion of the Issuer's Series A Preferred Stock in connection with the closing of the Issuer's initial public offering. The shares are held directly by SV Life SP LP. SV Health Investors, LLC is the Manager of SV Life SP LP. SV Fund VI GP is the general partner of SV Life SP LP. The general partner of SV Fund VI GP is SVLSF VI, LLC. The members of the investment committee of SVLSF VI, LLC are Kate Bingham, Thomas Flynn, James Garvey, Eugene D. Hill, III, Paul LaViolette, and Michael Ross. Each of SV Fund VI GP, SVLSF VI, LLC and the SVLSF VI, LLC investment committee disclaims beneficial ownership of the shares owned directly by SV Life SP LP, except to the extent of any pecuniary interest therein. Represents the total number of shares of Common Stock received by SV Life LP upon the conversion of the Issuer's Series B Preferred Stock in connection with the closing of the Issuer's initial public offering. Represents the total number of shares of Common Stock received by SV Life SP LP upon the conversion of the Issuer's Series B Preferred Stock in connection with the closing of the Issuer's initial public offering. All series of Convertible Preferred Stock automatically converted into the Issuer's Common Stock on a 4.132-for-1 basis on June 25, 2018 and had no expiration date. SV Life Sciences Fund VI, L.P., By: SV Life Sciences Fund VI (GP), L.P., Its: sole General Partner, By: SVLSF VI, LLC, ItsL sole General Partner, By: Brent M. Faduski, Officer, /s/ Brent M. Faduski 2018-06-25 SV Life Sciences Fund VI Strategic Partners, L.P., By: SV Life Sciences Fund VI (GP), L.P., Its: sole General Partner, By: SVLSF VI, LLC, Its: sole General Partner, By: Brent M. Faduski, Officer, /s/ Brent M. Faduski 2018-06-25 SV Life Sciences Fund VI (GP), L.P., By: SVLSF VI, LLC, Its: sole General Partner, By: Brent M. Faduski, Officer, /s/ Brent M. Faduski 2018-06-25 SVLSF VI, LLC, By: Brent M. Faduski, Officer, /s/ Brent M. Faduski 2018-06-25