CareDx (CDNA) 8-K Changes in Registrant's Certifying Accountant

Exhibit 16.1

April 16, 2018

Securities and Exchange Commission

100 F Street, N.E.

Washington, DC 20549

Ladies and Gentlemen:

We have read Item 4.01 of Form8-K dated April 16, 2018, of CareDx, Inc. and are in agreement with the statements contained in the first, second, third, and fifth paragraphs on page 2 therein. We have no basis to agree or disagree with other statements of the registrant contained therein.

/s/ Ernst & Young LLP