SEC Form DEFA14A filed by Design Therapeutics Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

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☐ Preliminary Proxy Statement

☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☐ Definitive Proxy Statement

☒ Definitive Additional Materials

☐ Soliciting Material Pursuant to § 240.14a-12

Design Therapeutics, Inc.

(Name of Registrant as Specified In Its Charter)

N/A

(Name of Person(s) Filing Proxy Statement if other than the Registrant)

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☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

DESIGN THERAPEUTICS P.O. BOX 8016, CARY, NC 27512-9903 Your vote matters! Design Therapeutics, Inc. Annual Meeting of Stockholders Tuesday, June 9, 2026 8:00 AM, Pacific Time Annual Meeting to be held live via the Internet - please visit www.proxydocs.com/DSGN for information. For a convenient way to view proxy materials, VOTE, and obtain directions to attend the meeting go to www.proxydocs.com/DSGN To vote your proxy while visiting this site, you will need the 12 digit control number in the box below. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. This is not a ballot. You cannot use this notice to vote your shares. We encourage you to access and review all of the important information contained in the proxy materials before voting. Under United States Securities and Exchange Commission rules, proxy materials do not have to be delivered in paper. Proxy materials can be distributed by making them available on the internet. If you want to receive a paper or e-mail copy of the proxy material, you must request one. There is no charge to you for requesting a copy. In order to receive a paper package in time for this year's meeting, you must make this request on or before May 29, 2026. Meeting Materials: Notice of Meeting and Proxy Statement & Annual Report or Form 10-K Important Notice Regarding the Availability of Proxy Materials for the Stockholders Meeting To Be Held On June 9, 2026 For Stockholders of record as of April 14, 2026 To order paper materials, use one of the following methods. Internet: www.investorelections.com/DSGN Call: 1-866-648-8133 Email: paper@investorelctins.com * If requesting material by e-mail, please send a blank e-mail with the 12 digit control number (located below) in the subject line. No other requests, instructions OR other inquiries should be included with your e-mail requesting material. Go Green! To receive documents via e-mail, simply go to: www.proxydocs.com/DSGN Your control number Have the 12 digit control number located in the box above available when you access the website and follow the instructions. SEE REVERSE FOR FULL AGENDA Copyright © 2026 BetaNXT, Inc. or its affiliates. All Rights Reserved

DESIGN THERAPEUTICS Design Therapeutics, Inc. Annual Meeting of Stockholders THE BOARD OF DIRECTORS RECOMMENDS A VOTE: FOR ON PROPOSALS 1 AND 2 PROPOSAL 1. To elect one nominee for Class II director named herein to serve for a three-year term until the 2029 Annual Meeting of Stockholders. 1.01 Simeon George, M.D. 2. To ratify the selection by the Audit Committee of the Board of Directors of Ernst & Young LLP as our independent registered public accounting firm for our fiscal year ending December 31, 2026.