X0306 4 2020-04-20 0 0001399529 Dicerna Pharmaceuticals Inc DRNA 0001243847 GREEN JOHN B C/O DICERNA PHARMACEUTICALS, INC. 33 HAYDEN AVENUE LEXINGTON MA 02421 0 1 0 0 Chief Financial Officer Common Stock 2020-04-20 4 M 0 25624 5.45 A 45045 D Common Stock 2020-04-20 4 S 0 25624 22.95 D 19421 D Employee Stock Option (Right to Buy) 5.45 2020-04-20 4 M 0 25624 0.00 D 2026-04-14 Common Stock 25624 186375 D Includes shares acquired under the DRNA 2014 Employee Stock Purchase Plan in transactions that were exempt under Rule 16b-3(c). The reporting person sold an aggregate of 25,624 shares of common stock on April 20, 2020 (the "Shares Sold") as reported in this Form 4. The Shares Sold represent 4.01% of 638,583 shares of common stock, which is the number of shares of common stock owned by the reporting person prior to the Shares Sold transactions reported in this Form 4, as well as shares issuable upon exercise or settlement of vested and unvested options and restricted stock units held by the reporting person as of the date of this report. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 17, 2019. As of the transaction date, the option was fully vested. The option vested 25% after the first year anniversary of the vesting start date of April 14, 2016 and the remaining 75% vested in 36 substantially equal monthly installments thereafter, subject in each case to the reporting person's continued service with the issuer through the applicable vesting date. /s/ John B. Green 2020-04-22