POWER OF ATTORNEY

(FOR EXECUTING FORM ID, FORMS 3, 4 AND 5 AND SCHEDULES 13D AND 13G)

KNOW ALL BY THESE PRESENTS, that the undersigned hereby constitutes and appoints
Robin Praeger, signing individually, the undersigned's true and lawful
attorneys-in-fact and agents to:

(i)	prepare, execute in the undersigned's name and on the undersigned's behalf,
and submit to the Securities and Exchange Commission 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
Securities and Exchange Commission of reports required by Section 13(d) and
Section 16(a) of the Securities Exchange Act of 1934, as amended (the "Exchange
Act") or any rules or regulations promulgated thereunder;

(ii)	prepare, execute and file, for and on behalf of the undersigned with
respect to holdings of and transactions in securities issued by a company to the
undersigned or Versant Venture Capital I, L.P., Versant Side Fund I, L.P.,
Versant Affiliates Fund I-A, L.P., Versant Affiliates Fund I-B, L.P., Versant
Ventures I, LLC, Versant Venture Capital II, L.P., Versant Side Fund II, L.P.,
Versant Affiliates Fund II-A, L.P., Versant Ventures II, LLC, Versant Venture
Capital III, L.P., Versant Side Fund III, L.P., Versant Ventures III, LLC,
Versant Venture Capital IV, L.P., Versant Side Fund IV, L.P., Versant Ventures
IV, LLC, Versant Venture Capital V, L.P., Versant Affiliates Fund V, L.P.,
Versant Ophthalmic Affiliates Fund I, L.P., Versant Venture Capital V (Canada)
LP, Versant Ventures V, LLC and Versant Ventures V (Canada), L.P., any and all
documents and filings that are required or advisable to be made with the United
States Securities and Exchange Commission, any stock exchange or similar
authority, under the Exchange Act, including without limitation (a) any Joint
Filing Agreement under Rule 13d-1(k) of the Exchange Act (or any successor
provision thereunder), Schedule 13D and Schedule 13G (or any successor schedules
or forms adopted under the Exchange Act) and any amendments thereto in
accordance with Section 13 of the Exchange Act and the rules thereunder, and (b)
Forms 3, 4 and 5 and any amendments thereto in accordance with Section 16(a) of
the Exchange Act and the rules thereunder; and

(iii)	take any other action of any nature whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit, 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 is Versant Ventures assuming, any of the undersigned's responsibilities to
comply with the Exchange Act, including without limitation Sections 13 and 16 of
the Exchange Act.

This Power of Attorney shall remain in full force and effect until the earliest
to occur of (a) the undersigned is no longer required to file any form or
document with respect to the undersigned's holdings of and transactions in
securities issued by a company, (b) revocation by the undersigned in a signed
writing delivered to the foregoing attorney-in-fact or (c) as to any
attorney-in-fact individually, until such attorney-in-fact shall no longer be
employed by Versant Ventures.

I hereby declare that any act or thing lawfully done hereunder by the foregoing
attorneys-in-fact shall be binding on the undersigned as if done by myself.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 18th day of September, 2014.

/s/ Samuel D. Colella
Samuel D. Colella