ThZeal - The Zeal

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Fund X, L.P.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 1,084,527.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,084,527.00

Aggregate amount beneficially owned by each reporting person

1,084,527.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

3.1 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

ATLAS VENTURE ASSOCIATES X, L.P.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 1,084,527.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,084,527.00

Aggregate amount beneficially owned by each reporting person

1,084,527.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

3.1 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Associates X, LLC

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 1,084,527.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,084,527.00

Aggregate amount beneficially owned by each reporting person

1,084,527.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

3.1 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Fund XII, L.P.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 51,000.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 51,000.00

Aggregate amount beneficially owned by each reporting person

51,000.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

0.1 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Associates XII, L.P.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 51,000.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 51,000.00

Aggregate amount beneficially owned by each reporting person

51,000.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

0.1 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Associates XII, LLC

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 51,000.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 51,000.00

Aggregate amount beneficially owned by each reporting person

51,000.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

0.1 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Opportunity Fund I, L.P.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 592,908.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 592,908.00

Aggregate amount beneficially owned by each reporting person

592,908.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

1.7 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Associates Opportunity I, L.P.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 592,908.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 592,908.00

Aggregate amount beneficially owned by each reporting person

592,908.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

1.7 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Associates Opportunity I, LLC

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 592,908.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 592,908.00

Aggregate amount beneficially owned by each reporting person

592,908.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

1.7 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Opportunity Fund II, L.P.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 420,549.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 420,549.00

Aggregate amount beneficially owned by each reporting person

420,549.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

1.2 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Associates Opportunity II, LP

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 420,549.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 420,549.00

Aggregate amount beneficially owned by each reporting person

420,549.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

1.2 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

CUSIP No.

254604101

Name of reporting person

Atlas Venture Associates Opportunity II, LLC

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 420,549.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 420,549.00

Aggregate amount beneficially owned by each reporting person

420,549.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

1.2 %

Type of Reporting Person (See Instructions)

SCHEDULE 13D

Item 1.

Security and Issuer

(a)

Title of Class of Securities:

Common Stock, $0.0001 par value per share

(b)

Name of Issuer:

DISC MEDICINE, INC.

(c)

Address of Issuer's Principal Executive Offices:

321 ARSENAL STREET, SUITE 101, WATERTOWN, MASSACHUSETTS , 02472.

Item 1 Comment:

This Amendment No. 4 to Schedule 13D ("Amendment No. 4") is being filed as an amendment to the statement on Schedule 13D relating to common stock, par value $0.0001 per share of Disc Medicine, Inc., a Delaware corporation, as filed with the Securities and Exchange Commission (the "SEC") on February 16, 2021 (the "Initial Schedule 13D") and later amended on February 14, 2023 ("Amendment No. 1") , September 21, 2023 ("Amendment No. 2") and January 24, 2024 ("Amendment No. 3" and together with the Initial Schedule 13D, Amendment No. 1 and Amendment No. 2 the "Prior Schedule 13D"). All capitalized terms not otherwise defined herein shall have the meanings ascribed to the terms in the Prior Schedule 13D. The Prior Schedule 13D is hereby amended and supplemented as follows and, except as expressly amended below, the Prior Schedule 13D remains in full force and effect.

Item 5.

Interest in Securities of the Issuer

(a)

As of the date hereof, Atlas X is the record owner of 1,084,527 shares of Common Stock. AVA X LP is the general partner of Atlas X and AVA X LLC is the general partner of AVA X LP. Each of Atlas X, AVA X LP and AVA X LLC has shared voting and dispositive power over the shares held by Atlas X. As such, each of Atlas X, AVA X LP and AVA X LLC may be deemed to beneficially own the shares held by Atlas X. As of the date hereof, Atlas XII is the record owner of 51,000 shares of Common Stock. AVA XII LP is the general partner of Atlas XII and AVA XII LLC is the general partner of AVA XII LP. Each of Atlas XII, AVA XII LP and AVA XII LLC has shared voting and dispositive power over the shares held by Atlas XII. As such, each of Atlas XII, AVA XII LP and AVA XII LLC may be deemed to beneficially own the shares held by Atlas XII. As of the date hereof, AVOF is the record owner of 592,908 shares of Common Stock. AVAO LP is the general partner of AVOF and AVAO LLC is the general partner of AVAO LP. Each of AVOF, AVAO LP and AVAO LLC has shared voting and dispositive power over the shares held by AVOF. As such, each of AVOF, AVAO LP and AVAO LLC may be deemed to beneficially own the shares held by AVOF. As of the date hereof, AVOF II is the record owner of 420,549 shares of Common Stock. AVAO II LP is the general partner of AVOF II and AVAO II LLC is the general partner of AVAO II LP. Each of AVOF II, AVAO II LP and AVAO II LLC has shared voting and dispositive power over the shares held by AVOF II. As such, each of AVOF II, AVAO II LP and AVAO II LLC may be deemed to beneficially own the shares held by AVOF II. Each of the Fund X Reporting Persons, Fund XII Reporting Persons, Opportunity Fund Reporting Persons and Opportunity Fund II Reporting Persons may be deemed to beneficially own 3.1%, 0.1%, 1.7% and 1.2%, respectively, of the Issuer's outstanding Common Stock, which percentages are calculated based upon 34,765,581 shares of Common Stock outstanding as of July 31, 2025, as reported in the Issuer's Quarterly Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended June 30 on Form 10-Q, filed with the Securities and Exchange Commission on August 7, 2025. Collectively, the Reporting Persons beneficially own an aggregate of 2,148,984 shares of Common Stock, which represents an estimated 6.2% of the Issuer's outstanding Common Stock. The Fund X Reporting Persons, Fund XII Reporting Persons, Opportunity Fund Reporting Persons and the Opportunity Fund II Reporting Persons are under common control and as a result, the Reporting Persons may be deemed to be members of a group. However, the Reporting Persons disclaim such group membership, and this Schedule 13D shall not be deemed an admission that the Reporting Persons are members of a group for purposes of Section 13 or for any other purposes.

(b)

As of the date hereof, each of Atlas X, AVA X LP and AVA X LLC have shared voting power and shared dispositive power over 1,084,527 shares of Common Stock. As of the date hereof, each of Atlas XII, AVA XII LP and AVA XII LLC have shared voting power and shared dispositive power over 51,000 shares of Common Stock. As of the date hereof, each of AVOF, AVAO LP and AVAO LLC have shared voting power and shared dispositive power over 592,908 shares of Common Stock. As of the date hereof, each of AVOF II, AVAO II LP and AVAO II LLC have shared voting power and shared dispositive power over 420,549 shares of Common Stock.

(c)

The transactions in the common stock by the Reporting Persons during the past sixty days are set forth in Exhibit 99.1 and are incorporated herein by reference.

Item 7.

Material to be Filed as Exhibits.

Joint Filing Agreement

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Atlas Venture Fund X, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates X, L.P., its general partner, By: Atlas Venture Associates X, LLC, its general partner, By Ommer Chohan, CFO
Date:	08/15/2025

ATLAS VENTURE ASSOCIATES X, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates X, LLC, its general partner, By Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Associates X, LLC

Signature:	/s/ Ommer Chohan
Name/Title:	Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Fund XII, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates XII, L.P., its general partner, By: Atlas Venture Associates XII, LLC, its general partner, By Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Associates XII, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates XII, LLC, its general partner, By Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Associates XII, LLC

Signature:	/s/ Ommer Chohan
Name/Title:	Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Opportunity Fund I, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates Opportunity I, L.P., its GP, By: Atlas Venture Associates Opportunity I, LLC, its GP, By Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Associates Opportunity I, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates Opportunity I, LLC, its GP, By Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Associates Opportunity I, LLC

Signature:	/s/ Ommer Chohan
Name/Title:	Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Opportunity Fund II, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates Opportunity II, L.P., its GP, By: Atlas Venture Associates Opportunity II, LLC, its GP, By Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Associates Opportunity II, LP

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates Opportunity II, LLC, its GP, By Ommer Chohan, CFO
Date:	08/15/2025

Atlas Venture Associates Opportunity II, LLC

Signature:	/s/ Ommer Chohan
Name/Title:	Ommer Chohan, CFO
Date:	08/15/2025