X0306 4 2021-03-30 0 0001807120 Design Therapeutics, Inc. DSGN 0001595117 George Simeon C/O DESIGN THERAPEUTICS, INC. 6005 HIDDEN VALLEY ROAD, SUITE 110 CARLSBAD CA 92011 1 0 1 0 Common Stock 2021-03-30 4 C 0 4439839 A 4439839 I See footnote Common Stock 2021-03-30 4 C 0 936637 A 5376476 I See footnote Common Stock 2021-03-30 4 P 0 250000 20.00 A 5626476 I See footnote Series A Preferred Stock 2021-03-30 4 C 0 7236938 0.00 D Common Stock 4439839 0 I See footnote Series B Preferred Stock 2021-03-30 4 C 0 1526718 0.00 D Common Stock 936637 0 I See tootnote All outstanding shares of Preferred Stock automatically converted into shares of Common Stock immediately upon the closing of the Issuer's initial public offering, for no additional consideration at a rate of one share of Common Stock for each 1.63 shares of Preferred Stock, based on the conversion price currently in effect. The Preferred Stock has no expiration date. The reported securities are held directly by SR One Capital Fund I Aggregator, LP. SR One Capital Partners I, LP is the general partner of SR One Capital Fund I Aggregator, LP, and SR One Capital Management, LLC is the general partner of SR One Capital Partners I, LP. Simeon George, M.D. is the managing member of SR One Capital Management, LLC. Each of SR One Capital Partners I, LP, SR One Capital Management, LLC and Mr. George may each be deemed to have shared power to vote or dispose of these shares, and each disclaims beneficial ownership of the shares except to the extent of any pecuniary interest therein. The shares were purchased in the Issuer's initial public offering. /s/ Mustapha Parekh, Attorney-in-Fact 2021-03-31