13G Filing: Viking Global and Editas Medicine, Inc. (EDIT)

Schedule 13G PAGE 20 of 20

CUSIP No. 28106W103

SIGNATURES

After reasonable inquiry and to the best of our knowledge and belief,
the undersigned certify that the information set forth in this statement is
true, complete and correct.

DATED: February 9, 2016

/s/ O. ANDREAS HALVORSEN
By: O. Andreas Halvorsen – individually and
as an Executive Committee Member of
VIKING GLOBAL PERFORMANCE LLC, on behalf
of itself and VIKING GLOBAL EQUITIES LP,
VIKING GLOBAL EQUITIES II LP and VGE III PORTFOLIO LTD.,
and as an Executive Committee Member of
Viking Global Partners LLC, on behalf of
VIKING GLOBAL INVESTORS LP, and as
an Executive Committee Member of
VIKING LONG FUND GP LLC, on behalf of itself
and VIKING LONG FUND MASTER LTD., and as
an Executive Committee Member of
VIKING GLOBAL OPPORTUNITIES GP LLC, on behalf
of itself and VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC and
VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP

/s/ DAVID C. OTT
By: David C. Ott – individually and
as an Executive Committee Member of
VIKING GLOBAL PERFORMANCE LLC, on behalf
of itself and VIKING GLOBAL EQUITIES LP,
VIKING GLOBAL EQUITIES II LP and VGE III PORTFOLIO LTD.,
and as an Executive Committee Member of
Viking Global Partners LLC, on behalf of
VIKING GLOBAL INVESTORS LP, and as
an Executive Committee Member of
VIKING LONG FUND GP LLC, on behalf of itself
and VIKING LONG FUND MASTER LTD., and as
an Executive Committee Member of
VIKING GLOBAL OPPORTUNITIES GP LLC, on behalf
of itself and VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC and
VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP

/s/ DANIEL S. SUNDHEIM
By: Daniel S. Sundheim – individually and
as an Executive Committee Member of
VIKING GLOBAL PERFORMANCE LLC, on behalf
of itself and VIKING GLOBAL EQUITIES LP,
VIKING GLOBAL EQUITIES II LP and VGE III PORTFOLIO LTD.,
and as an Executive Committee Member of
Viking Global Partners LLC, on behalf of
VIKING GLOBAL INVESTORS LP, and as
an Executive Committee Member of
VIKING LONG FUND GP LLC, on behalf of itself
and VIKING LONG FUND MASTER LTD., and as
an Executive Committee Member of
VIKING GLOBAL OPPORTUNITIES GP LLC, on behalf
of itself and VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC and
VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP