Liminal BioSciences : Arrangement Circular – Special Meeting September 2023

These materials are important and require your immediate attention. They require shareholders of Liminal BioSciences Inc. to make important decisions. If you are in doubt about how to make such decisions, please contact your financial, legal, tax or other professional advisors. If you are a shareholder of Liminal BioSciences Inc. and have any questions regarding the information contained in this management information circular or require assistance in completing your form of proxy, voting instructions form or the letter of transmittal, please contact Carson Proxy Advisors, the Company's proxy solicitor, at North American toll free phone at 1-800-530-5189, local (collect outside North America): 416-751-2066 or by email at info@carsonproxy.com.

Shareholders in the United States should read the section "Notice to Shareholders in the United States" on page 3 of the accompanying management information circular.

Notice of Special Meeting of Shareholders of

Liminal BioSciences Inc.

to be held on September 15, 2023 at 8:00 a.m.

and

Management Information Circular

with respect to an

Arrangement

involving

Liminal BioSciences Inc.

and

Structured Alpha LP

Dated August 16, 2023

YOUR VOTE IS IMPORTANT. TAKE ACTION AND VOTE TODAY.

The Board of Directors (other than the Recusing Directors), acting on the

unanimous recommendation of the Special Committee, unanimously recommends that you vote IN FAVOUR of the Arrangement Resolution.

NEITHER THE U.S. SECURITIES AND EXCHANGE COMMISSION, THE NASDAQ CAPITAL MARKET NOR THE SECURITIES REGULATORY AUTHORITY IN ANY STATE IN THE UNITED STATES HAS APPROVED OR DISAPPROVED OF THE ARRANGEMENT OR PASSED UPON THE FAIRNESS OR MERITS OF THE ARRANGEMENT, NOR HAS THE U.S. SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES REGULATORY AUTHORITIES OF ANY STATE IN THE UNITED STATES PASSED ON THE ADEQUACY OR ACCURACY OF THIS CIRCULAR. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENCE. IN ADDITION, NO CANADIAN SECURITIES REGULATORY AUTHORITY HAS IN ANY WAY PASSED UPON THE MERITS OF THE TRANSACTION DESCRIBED IN THIS CIRCULAR, AND ANY REPRESENTATION OTHERWISE IS AN OFFENCE.

Letter to Shareholders

August 16, 2023

Dear Shareholders:

The board of directors (the "Board") of Liminal BioSciences Inc. (the "Company" or "Liminal BioSciences") cordially invites you to attend a special meeting (the "Meeting") of the holders (the "Shareholders") of common shares (the "Shares") of the Company to be held as a virtual only meeting via a live webcast on Friday, September 15, 2023 at 8:00 a.m. (Eastern time) athttps://web.lumiagm.com/465634100.

At the Meeting, pursuant to the interim order (the "Interim Order") of the Ontario Superior Court of Justice (Commercial List) (the "Court"), as same may be amended, the Shareholders will be asked to consider and, if deemed advisable, to pass, with or without variation, a special resolution approving a statutory plan of arrangement (the "Arrangement") involving the Company and Structured Alpha LP ("SALP" or the "Purchaser") pursuant to the provisions of the Canada Business Corporations Act.

Under the Arrangement, SALP will acquire directly or indirectly all of the issued and outstanding Shares of the Company not currently owned by SALP or its affiliates and associates (the "Minority Shares") at a price of US$8.50 per Share, payable in cash (the "Consideration").

A special committee of the Board consisting entirely of disinterested directors (the "Special Committee") conducted, with the assistance of its legal and financial advisors, a review of the Company's alternatives available to the Company and obtained an independent valuation of the Shares. Following this process, and after, among other things, receiving outside legal and financial advice in evaluating the Arrangement and careful consideration of various matters, the Special Committee unanimously determined (i) that the Arrangement is fair to the holders of Minority Shares (the "Minority Shareholders") and (ii) that the Arrangement and the entering into of the Arrangement Agreement (as defined below) is in the best interests of the Company, and unanimously recommended that the Board approve the Arrangement and recommends that the Minority Shareholders vote IN FAVOURof the Arrangement Resolution.

On the unanimous recommendation of the Special Committee, and after, among other things, receiving outside legal and financial advice in evaluating the Arrangement and careful consideration of various matters, the Board, with Messrs. Eugene Siklos and Alek Krstajic (being the two directors on the Board affiliated with SALP) having recused themselves, unanimously determined (i) that the Arrangement is fair to Minority Shareholders and (ii) that the Arrangement and the entering into of the Arrangement Agreement is in the best interests of the Company, and recommends that the Minority Shareholders vote IN FAVOURof the Arrangement Resolution.

In evaluating the Arrangement, the Special Committee consulted with the Company's management and the Special Committee's legal and financial advisors and carefully reviewed the proposed Arrangement and the terms and conditions of the Arrangement Agreement and related agreements and documents and, in determining that the Arrangement is in the best interests of the Company and fair to the Minority Shareholders, the Special Committee considered and relied upon a number of substantive factors as more fully described in the accompanying management information circular (the "Circular").

To be effective, the Arrangement must be approved by a special resolution (the "Arrangement Resolution"), the full text of which is outlined in Appendix A of the Circular, passed by at least (i) two-thirds (662/3%) of the votes cast by Shareholders virtually present or represented by proxy at the Meeting, voting as a single class (each holder of Shares being entitled to one vote per Share) and (ii) the approval of the majority of the holders of Shares virtually present or represented by proxy at the Meeting, excluding the votes of Shareholders whose votes are required to be excluded for the purposes of "minority approval" under Multilateral Instrument 61-101 - Protection of Minority Security

Holders in Special Transactions in the context of a "business combination", including the Shares over which SALP and its affiliates and associates exercise control or direction.

The Arrangement is subject to certain closing conditions, including approval by the Shareholders, by the court and receipt of applicable regulatory approvals. Subject to those closing conditions being satisfied or waived (if permitted) and satisfying other customary conditions contained in the arrangement agreement dated July 11, 2023 among the Company and the Purchaser (the "Arrangement Agreement"), it is anticipated that the Arrangement will be completed at or around the end of September 2023. Further details of the Arrangement are set out in the accompanying Circular.

In connection with the Arrangement, all directors and executive officers of the Company entered into voting agreements pursuant to which they have agreed, subject to the terms hereof, to vote all of their Shares IN FAVOURof the Arrangement Resolution and against any resolution submitted by any other person that is inconsistent with the Arrangement.

Shareholders should review the accompanying notice of special meeting of Shareholders and management information circular which describes, among other things, the background to the Arrangement as well as the reasons for the determinations and recommendations of the Special Committee and the Board. The Circular contains a detailed description of the Arrangement, including certain risk factors relating to the completion of the Arrangement. You should consider carefully all of the information in the Circular. If you require assistance, you are urged to consult your financial, legal, tax or other professional advisor.

Your vote is important regardless of the number of Shares you hold. Whether or not you are able to attend the Meeting, you are urged to complete, sign, date and return the enclosed form of proxy or voting instruction form so that your Shares can be voted at the Meeting or any adjournment(s) or postponement(s) thereof in accordance with your voting instructions. Your votes must be received by Liminal BioSciences' transfer agent, Computershare Trust Company of Canada, no later than 5:00 p.m. (Eastern time) on September 13, 2023, or, if the Meeting is adjourned or postponed, by 5:00 p.m. (Eastern time) two Business Days before the day on which the Meeting is reconvened.

Non-registered Shareholders who hold their Shares through a broker, investment dealer, bank, trust company, custodian, nominee or other intermediary, should carefully follow the instructions of their intermediary to ensure that their Shares are voted at the Meeting in accordance with such Shareholder's instructions, to arrange for their Intermediary to complete the necessary transmittal documents and to ensure that they receive payment for their Shares if the Arrangement is completed.

If you are a Shareholder of Liminal BioSciences and have any questions regarding the information contained in the accompanying Circular or require assistance in completing your form of proxy, voting instructions form or the letter of transmittal, please contact Carson Proxy Advisors the Company's proxy solicitor, at North American toll free phone at 1-800-530-5189, local (collect outside North America): 416-751-2066 or by email at info@carsonproxy.com.

On behalf of Liminal BioSciences, we would like to thank all Shareholders for their ongoing support as we prepare to take part in this very important milestone event for Liminal BioSciences.

Yours very truly,

1. Neil A. Klompas Neil A. Klompas
   Chair of the Special Committee

Liminal BioSciences Inc.

Notice of Special Meeting of Shareholders

Laval, Québec, Canada, August 16, 2023.

NOTICE IS HEREBY GIVEN that, pursuant to an interim order of the Ontario Superior Court of Justice (Commercial List) dated August 16, 2023 (as same may be amended, the "Interim Order"), a special meeting (the "Meeting") of holders (the "Shareholders") of common shares (the "Shares") of Liminal BioSciences Inc. (the "Company" or "Liminal BioSciences") will be conducted as a virtual only meeting via a live webcast on Friday, September 15, 2023 at 8:00 a.m. (Eastern time) at https://web.lumiagm.com/465634100. The purpose of the Meeting is to:

1 to consider pursuant to the Interim Order and, if thought advisable, to pass, with or without variation, a special resolution (the "Arrangement Resolution"), the full text of which is set forth in Appendix A attached to the accompanying management information circular (the "Circular"), approving a statutory plan of arrangement (the "Arrangement") under the provisions of Section 192 of the Canada Business Corporations Act (the "CBCA") involving Liminal BioSciences and Structured Alpha LP ("SALP" or the "Purchaser"), the whole as more particularly described in the accompanying Circular; and

2 to transact such other business as may properly come before the Meeting or any adjournment(s) or postponement(s) thereof.

The Circular provides additional information relating to the matters to be addressed at the Meeting, including the Arrangement.

In the event necessary to address material comments from any securities regulatory authority, including from the SEC, on this Circular or the Schedule 13E-3, the Parties have agreed pursuant to the Arrangement Agreement that the Company may postpone or adjourn the Meeting.

Shareholders are reminded to review the accompanying Circular carefully before voting because it has been prepared to help you make an informed decision.

Participating at the Meeting

The Company is holding the Meeting as a virtual only meeting, which will be conducted via live webcast, where all shareholders regardless of geographic location and equity ownership will have an equal opportunity to participate at the Meeting and engage management as well as other shareholders. Shareholders will not be able to attend the Meeting in person. The Company views the use of technology-enhancedshareholder communications as a method to facilitate individual investor participation, making the Meeting more accessible and engaging for all involved, by permitting a broader base of shareholders to participate in the Meeting, which is consistent with the goals of the regulators, stakeholders, and others invested in the corporate governance process. Registered shareholders and duly appointed proxyholders will be able to attend, participate and vote at the Meeting online athttps://web.lumiagm.com/465634100(meeting ID: 465-634-100). Non-registeredshareholders (being shareholders who hold their shares through a broker, investment dealer, bank, trust company, custodian, nominee or other intermediary) who have not duly appointed themselves as proxyholder will not be able to attend, participate, vote or ask questions at the Meeting.

A shareholder who wishes to appoint a person other than the management nominees identified on the form of proxy or voting instruction form to represent him, her or it at the Meeting may do so by inserting such person's name in the blank space provided in the form of proxy or voting instruction form and following the instructions for submitting such form of proxy or voting instruction form. This must be completed prior to registering such proxyholder, which is an additional step to be completed once you have submitted your form of proxy or voting instruction form. If you wish that a person other than the Company nominees identified on the form of proxy or voting instruction form