X0306 4 2022-12-19 0 0001807120 Design Therapeutics, Inc. DSGN 0001534986 Siffert Joao MD C/O DESIGN THERAPEUTICS, INC. 6005 HIDDEN VALLEY ROAD, SUITE 110 CARLSBAD CA 92011 1 1 0 0 President and CEO Common Stock 2022-12-19 4 P 0 1150 8.47 A 126319 D Common Stock 2022-12-20 4 P 0 6300 8.375 A 132619 D Includes 1,250 shares acquired under the Issuer's 2021 Employee Stock Purchase Plan ("ESPP") on November 15, 2021 and 1,220 shares acquired under the ESPP on May 13, 2022. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $8.32 to $8.44, inclusive. The Reporting Person undertakes to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each price within the range set forth herein. /s/ Mustapha Parekh, Attorney-in-Fact 2022-12-21