13D Filing: RA Capital Management and Dicerna Pharmaceuticals Inc (DRNA)

As of the date hereof,
each share of Preferred Stock has an accrued value of $100 and is convertible into approximately 31 shares of the Common Stock
(with cash in lieu of fractional shares), at a conversion price of $3.19. Therefore, as of the date hereof, the Preferred Stock
owned by the Reporting Persons would be convertible into 2,398,118 shares of the Common Stock, of which 1,956,865 shares would
be held by the Fund and 441,253 shares would be held by the Account.

The foregoing description of
the Preferred Stock does not purport to be complete and is qualified in its entirety by the full text of the Certificate of Designation
of Redeemable Convertible Preferred Stock of Dicerna Pharmaceuticals, Inc., a copy of which is filed as Exhibit 3.1 to the Company’s
Form 8-K filed with the SEC on March 30, 2017.

(d) Not applicable.

(e) Not applicable.

Item
6. Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer

Not applicable.

Item
7. Material to Be Filed as Exhibits

Exhibit 1 Joint Filing Agreement by and
among the Reporting Persons.