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 Michael Todisco, 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. (the "Company"), Forms 3, 4, and 5 in accordance
         with Section 16(a) of the Exchange Act and the rules 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
earliest of (a) the undersigned is no longer required to file Forms 3, 4, and 5
in accordance with Section 16(a) of the Exchange Act and the rules thereunder
with respect to the undersigned's holdings of and transactions in securities
issued by the Company, (b) neither Douglas Fambrough nor Michael Todisco is
employed by the Company, or (c) if revoked by the undersigned in a signed
writing delivered to each such attorney-in-fact.

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 4th day of February, 2016.

                                 /s/Dennis H. Langer, M.D., J.D.
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                                         Signature

                                 Dennis H. Langer, M.D., J.D.
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