13G Filing: Jafco Sv4 Investment Limited Partnership and Miragen Therapeutics Inc. (NASDAQ:MGEN)

Page 8 of 8

Page 8 of 8 – SEC Filing

CUSIP No. 60463E103 Page 8 of 8

Exhibit A

Agreement of Joint Filing

The undersigned hereby
agree that a single Schedule 13G (or any amendment thereto) relating to the common stock of the Issuer shall be filed on behalf
of each of the undersigned and that this Agreement shall be filed as an exhibit to such Schedule 13G.

Date: March 31, 2017

JAFCO SV4 Investment Limited Partnership
By: JAFCO Co., Ltd.
Its: General Partner
By: /s/ Miwa Toyoda
Miwa Toyoda, Principal
JAFCO Co., Ltd.
By: /s/ Miwa Toyoda
Miwa Toyoda, Principal

Follow Viridian Therapeutics Inc. (NASDAQ:VRDN)

Page 8 of 8