Liminal BioSciences : Letter of Transmittal – Special Meeting September 2023

You are strongly urged to read the accompanying Liminal BioSciences Inc. Management Information Circular dated August 16, 2023 before completing this Letter of Transmittal.

This is not a form of proxy for the purposes of the special meeting of shareholders of Liminal Biosciences Inc. to be held on September 15, 2023. A form of proxy has been distributed by Limital Biosciences Inc. for use in connection with such meeting and must be completed for the common shares represented by this Letter of Transmittal to be voted at the special meeting.

The Instructions accompanying this Letter of Transmittal should be read carefully before this Letter of Transmittal is completed. Your broker or other financial advisor can assist you in completing this Letter of Transmittal.

LETTER OF TRANSMITTAL

FOR REGISTERED HOLDERS OF COMMON SHARES

OF

LIMINAL BIOSCIENCES INC.

This Letter of Transmittal, properly completed and duly executed by the registered holders (the "Shareholders") of common shares (the "Shares") of Liminal BioSciences Inc. ("Liminal BioSciences" or the "Company"), together with all other required documents, must accompany certificate(s) or DRS Advice(s) (each, a "Share Instrument") for the Shares deposited in connection with the proposed arrangement (the "Arrangement") involving Liminal BioSciences and Structured Alpha LP ("SALP" or the "Purchaser"), a limited partnership existing under the laws of the Cayman Islands, managed by its general partner, Thomvest Asset Management Ltd., pursuant to an arrangement agreement among Liminal BioSciences and the Purchaser dated July 11, 2023 (as may by further amended, supplemented and/or restated in accordance therewith, the "Arrangement Agreement"). The Arrangement will be submitted for approval at the special meeting of Shareholders of Liminal BioSciences to be held on September 15, 2023 (the "Meeting") as described in a management information circular of Liminal BioSciences dated August 16, 2023 (the "Circular"). Capitalized terms used but not defined in this Letter of Transmittal have the meanings set out in the Circular. Copies of the Circular and the Arrangement Agreement are available under the Company's profile on SEDAR+ at www.sedarplus.ca and on EDGAR at www.sec.gov.

The Arrangement is expected to close on or about September 30, 2023. At the Effective Time, SALP will acquire all of the issued and outstanding Shares of the Company not currently owned by SALP or its affiliates and associates at a price of US$8.50 per Share, payable in cash (the "Consideration").

This Letter of Transmittal is for use by registered holders of Shares only or their authorized representatives and is not to be used by beneficial holders of Shares that are not also registered holders of Shares ("Beneficial Shareholders"). A Beneficial Shareholder does not have Shares registered in its name; rather, such Shares are held by an intermediary on its behalf. If you are a Beneficial Shareholder, you should contact your intermediary for instructions and assistance in receiving the Consideration for your Shares.

Please note that the delivery of this Letter of Transmittal, together with the Share Instruments representing your Shares, does not constitute a vote in favour of the Arrangement. To exercise your right to vote at the Meeting, you must follow the instructions provided in the form of proxy that accompanies the Circular.

If you are a U.S. Person (as defined in Instruction 6), you must also complete the Substitute Form W-9 included set forth herein. If you are not a U.S. Person but have a U.S. mailing address, see Instruction 6.

Any Share Instrument(s) representing Shares which have not been duly surrendered, with all other documents required by the Depositary (as defined below), on or before the date that is three (3) years from the Effective Date, will cease to represent a claim against or interest of any kind or nature in the Company, the Purchaser or the

Depositary. Accordingly, Shareholders who do not deliver their Share Instrument(s) and all other required documents to the Depositary on or before the date that is three (3) years from the Effective Date will lose their right to receive the Consideration for their Shares.

Please read the Circular and the instructions set out below carefully before completing this Letter of Transmittal. Delivery of this Letter of Transmittal to an address other than as set forth on the back of this Letter of Transmittal will not constitute a valid delivery. If Shares are registered in different names, a separate Letter of Transmittal must be submitted for each different registered owner.

It is further acknowledged that the Company and/or the Purchaser may be required to disclose personal information in respect of the undersigned, and the undersigned consents to disclosure of personal information in respect of the undersigned to (i) stock exchanges or securities regulatory authorities, (ii) the Depositary, (iii) any of the parties to the Arrangement Agreement and (iv) legal counsel to any of the parties to the Arrangement Agreement.

The undersigned irrevocably constitutes and appoints the Depositary and any other person designated by the Purchaser in writing, the true and lawful agent, attorney and attorney-in-fact of the undersigned with respect to the Deposited Shares purchased in connection with the Arrangement with full power of substitution (such power of attorney, being coupled with an interest, being irrevocable) to, in the name of and on behalf of the undersigned,

1. register or record the transfer of such Deposited Shares consisting of securities on the registers of Liminal BioSciences; and (b) execute and negotiate any cheques or other instruments representing any such distribution payable to or to the order of the undersigned.

Except for any proxy deposited with respect to the vote on the Arrangement Resolution in connection with the Meeting, the undersigned revokes any and all other authority, whether as agent, attorney-in-fact, attorney, proxy or otherwise, previously conferred or agreed to be conferred by the undersigned at any time with respect to the Deposited Shares or any distributions other than as set out in this Letter of Transmittal and in any proxy granted for use at the Meeting. Other than in connection with the Meeting, no subsequent authority, whether as agent, attorney- in-fact, attorney, proxy or otherwise, will be granted with respect to the Deposited Shares or any distributions by or on behalf of the undersigned, unless the Deposited Shares are not taken up and paid for in connection with the Arrangement. The undersigned covenants and agrees to execute all such documents, transfers and other assurances as may be necessary or desirable to convey the Deposited Shares and distributions effectively to the Purchaser as and form the Effective Time. Each authority conferred or agreed to be conferred by the undersigned in this Letter of Transmittal may be exercised during any subsequent legal incapacity of the undersigned and all obligations of the undersigned in this Letter of Transmittal shall be binding upon the heirs, personal representatives, successors and assigns of the undersigned. The undersigned acknowledges that the covenants, representations and warranties of the undersigned contained herein shall survive the completion of the Arrangement.

The undersigned instructs the Purchaser and the Depositary, upon the Arrangement becoming effective, to deliver or arrange to be delivered the Consideration for the Deposited Shares, by wire transfer of immediately available funds in accordance with the wire instructions set forth in BOX E below, if duly completed by the undersigned, or by mailing cheques by first class mail, postage prepaid, to the address of record of the undersigned, or to hold such cheques for pick-up, in accordance with the instructions given below. Should the Arrangement not proceed for any reason, the deposited Share Instruments and other relevant documents shall be returned in accordance with the instructions in the preceding sentence.

The undersigned acknowledges and agrees that the method of delivery of the Share Instrument(s) representing the Deposited Shares and all other required documents is at the election and risk of the undersigned. The undersigned acknowledges that there shall be no duty or obligation on Liminal BioSciences, the Purchaser, the Depositary or any other Person to give notice of any defect or irregularity in any deposit and no liability shall be incurred by any of them for failure to give such notice. The Company and the Purchaser reserve the right, if they so elect, in their absolute discretion, to instruct the Depositary to waive any defect or irregularity contained in any Letter of Transmittal received by the Depositary. The granting of a waiver to one or more Shareholders does not constitute a waiver for any other Shareholder(s). The Company and the Purchaser reserve the right to demand strict compliance with the terms of this Letter of Transmittal and the Arrangement.

By reason of the use by the undersigned of an English language form of Letter of Transmittal, the undersigned shall be deemed to have required that any contract evidenced by the Arrangement as accepted through this Letter of Transmittal, as well as all documents related thereto, be drawn exclusively in the English language. En raison de l'usage d'une lettre d'envoi en langue anglaise par le soussigné, le soussigné et les destinataires sont présumés d'avoir requis que tout contrat attesté par l'arrangement et son acceptation par cette lettre d'envoi, de même que tous les documents qui s'y rapportent, soient rédigés exclusivement en langue anglaise.