LIMITED POWER OF ATTORNEY FOR
                             SECTION 16 REPORTING OBLIGATIONS

       Know all by these presents, that the undersigned hereby makes,
constitutes and appoints each of Douglas Fambrough and John B. Green, or either
of them acting individually, and with full power of substitution, the
undersigned's true and lawful attorney-in-fact to:

     (1)     prepare, execute in the undersigned's name and on the undersigned's
             behalf, and submit to the U.S. Securities and Exchange Commission
             (the "SEC") a Form ID, including amendments thereto, and any other
             documents necessary or appropriate to obtain codes and passwords
             enabling the undersigned to make electronic filings with the SEC of
             reports required by Section 16(a) of the Securities Exchange Act of
             1934 (the "Exchange Act") or any rule or regulation of the SEC;

     (2)     execute for and on behalf of the undersigned, in the undersigned's
             capacity as an officer and/or director of Dicerna Pharmaceuticals,
             Inc., a Delaware corporation (the "Company"), Forms 3, 4, and 5,
             including amendments thereto, in accordance with Section 16(a) of
             the Exchange Act and the rules and regulations thereunder;

     (3)     seek or obtain, as the undersigned's representative and on the
             undersigned's behalf, information on transactions in the Company's
             securities from any third party, including brokers, employee
             benefit plan administrators and trustees, and the undersigned
             hereby authorizes any such person to release any such information
             to the undersigned and approves and ratifies any such release of
             information;

     (4)     do and perform any and all acts for and on behalf of the
             undersigned which may be necessary or desirable to complete and
             execute any such Form 3, 4, or 5, complete and execute any
             amendment or amendments thereto, and timely file such form with the
             SEC and any stock exchange or similar authority; and

     (5)     take any other action of any type whatsoever in connection with the
             foregoing which, in the opinion of such attorney-in-fact, may be of
             benefit to, in the best interest of, or legally required by, the
             undersigned, it being understood that the documents executed by
             such attorney-in-fact on behalf of the undersigned pursuant to this
             Power of Attorney shall be in such form and shall contain such
             terms and conditions as such attorney-in-fact may approve in such
             attorney-in-fact's discretion.

       The undersigned hereby grants to each such attorney-in-fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and the
rights and powers herein granted. The undersigned acknowledges that the
foregoing attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming nor relieving, nor is the Company assuming nor
relieving, any of the undersigned's responsibilities to comply with Section 16
of the Exchange Act.  The undersigned acknowledges that neither the Company nor
the foregoing attorneys-in-fact assume (i) any liability for the undersigned's
responsibility to comply with the requirement of the Exchange Act, (ii) any
liability of the undersigned for any failure to comply with such requirements,
or (iii) any obligation or liability of the undersigned for profit disgorgement
under Section 16(b) of the Exchange Act.

       This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier (a) revoked by the undersigned in a signed writing delivered to
the foregoing attorneys-in-fact or (b)superseded by a new power of attorney
regarding the purposes outlined herein at a later date.

       IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 28th day of August, 2019.

                                          /s/ Patrick M. Gray
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                                          Signature

                                          Patrick M. Gray
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