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| The 2022 Annual Meeting of Stockholders of Sigilon Therapeutics, Inc. will be held on May 26, 2022 at 8 am EDT, at Sigilon Therapeutics, Inc., 100 Binney Street, Suite 600, Cambridge, Massachusetts. Proposals to be voted on at the meeting are listed below along with the Board of Directors’ recommendations. The Board of Directors recommend a vote FOR all the nominees listed and FOR Proposal 2: 1.Election of Directors: 01 - Rogerio Vivaldi Coelho, M.D. 02 - John Cox 03 – Kavita Patel, M.D. 2.To ratify the appointment of PricewaterhouseCoopers LLP as Sigilon Therapeutic, Inc.’s independent registered public accounting firm for the fiscal year ending December 31, 2022. PLEASE NOTE – YOU CANNOT VOTE BY RETURNING THIS NOTICE. To vote your shares you must go online or request a paper copy of the proxy materials to receive a proxy card. Here’s how to order a copy of the proxy materials and select delivery preferences: Current and future delivery requests can be submitted using the options below. If you request an email copy, you will receive an email with a link to the current meeting materials. PLEASE NOTE: You must use the number in the shaded bar on the reverse side when requesting a copy of the proxy materials. — — — Internet – Go to www.envisionreports.com/SGTX. Click Cast Your Vote or Request Materials. Phone – Call us free of charge at 1-866-641-4276. Email – Send an email to investorvote@computershare.com with “Proxy Materials Sigilon Therapeutics, Inc.” in the subject line. Include your full name and address, plus the number located in the shaded bar on the reverse side, and state that you want a paper copy of the meeting materials. To facilitate timely delivery, all requests for a paper copy of proxy materials must be received by May 13, 2022. Stockholder Meeting Notice |