XGN Exagen Inc

CUSIP No. 30068X103

1.

Names of Reporting Persons
Tullis-Dickerson Capital Focus III, L.P.

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power

6.

Shared Voting Power
1,222,670

7.

Sole Dispositive Power

8.

Shared Dispositive Power
1,222,670

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
1,222,670

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
9.7%

12.

Type of Reporting Person (See Instructions)
PN

CUSIP No. 30068X103

1.

Names of Reporting Persons
Tullis Dickerson Partners III, L.L.C.

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power

6.

Shared Voting Power
1,222,670

7.

Sole Dispositive Power

8.

Shared Dispositive Power
1,222,670

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
1,222,670

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
9.7%

12.

Type of Reporting Person (See Instructions)
PN

CUSIP No. 30068X103

1.

Names of Reporting Persons
Tullis Growth Fund, L.P.

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power

6.

Shared Voting Power
751,443

7.

Sole Dispositive Power

8.

Shared Dispositive Power
751,443

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
751,443

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
6%

12.

Type of Reporting Person (See Instructions)
PN

CUSIP No. 30068X103

1.

Names of Reporting Persons
Tullis-Growth Partners, L.L.C.

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power

6.

Shared Voting Power
751,443

7.

Sole Dispositive Power

8.

Shared Dispositive Power
751,443

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
751,443

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
6%

12.

Type of Reporting Person (See Instructions)
PN

CUSIP No. 30068X103

1.

Names of Reporting Persons
Tullis Growth Fund II, L.P.

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power

6.

Shared Voting Power
105,453

7.

Sole Dispositive Power

8.

Shared Dispositive Power
105,453

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
105,453

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
0.8%

12.

Type of Reporting Person (See Instructions)
PN

CUSIP No. 30068X103

1.

Names of Reporting Persons
Tullis-Growth Partners II, L.L.C.

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power

6.

Shared Voting Power
105,453

7.

Sole Dispositive Power

8.

Shared Dispositive Power
105,453

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
105,453

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
0.8%

12.

Type of Reporting Person (See Instructions)
PN

CUSIP No. 30068X103

1.

Names of Reporting Persons
James L.L. Tullis

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
United States

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
54,540

6.

Shared Voting Power
2,079,566

7.

Sole Dispositive Power
54,540

8.

Shared Dispositive Power
2,079,566

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
2,134,106

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
17.0%

12.

Type of Reporting Person (See Instructions)
IN

Item 1.

(a)

Name of Issuer
Exagen, Inc.

(b)

Address of Issuer’s Principal Executive Offices
1261 Liberty Way, Suite C, Vista, CA 92081

Item 2.

(a)

Name of Person Filing
This statement is being filed on behalf of each of the following persons (each, a “Reporting Person” and collectively, the “Reporting Persons”):

i.                  Tullis-Dickerson Capital Focus III, L.P. (“TD Capital Focus”)

ii.               Tullis-Dickerson Partners III, L.L.C., the general partner of TD Capital Focus

iii.            Tullis Growth Fund, L.P. (“Tullis Growth Fund”)

iv.           Tullis-Growth Partners, L.L.C., the general partner of Tullis Growth Fund

v.              Tullis Growth Fund II, L.P. (“Tullis Growth Fund II”)

vi.           Tullis-Growth Partners II, L.L.C., the general partner of Tullis Growth Fund II

vii.        James L.L. Tullis as a principal of each of the foregoing entities and in his individual capacity

(b)

Address of Principal Business Office or, if none, Residence
The address of the principal business office of each of the Reporting Persons is 11770 US Highway One, Suite 503, Palm Beach Gardens, FL 33408

(c)

Citizenship
James L. L. Tullis is a citizen of the United States and each of the remaining Reporting Persons were formed in Delaware

(d)

Title of Class of Securities
Common Stock

(e)

CUSIP Number
30068X103

Item 3.

If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

o

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)

o

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)

o

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)

o

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)

o

An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)

o

An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)

o

A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);

(h)

o

A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

o

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

o

A non-U.S. institution in accordance with § 240.13d–1(b)(1)(ii)(J);

(k)

o

Group, in accordance with § 240.13d–1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with

§ 240.13d–1(b)(1)(ii)(J), please specify the type of institution:____________________________

Item 4.

Ownership

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

(a)

Amount beneficially owned:   

See row 9 of the cover page of each Reporting Person.

As of December 31, 2019, the general partner of Tullis-Dickerson Capital Focus III, L.P., Tullis Dickerson Partners III, L.L.C. is deemed to beneficially own 1,222,670 shares of the Issuer’s common stock. As the general partner of Tullis Growth Fund, L.P. , Tullis-Growth Partners, L.L.C. is deemed to beneficially own 751,443 shares of the Issuer’s common stock.  As the general partner of Tullis Growth Fund II, L.P., Tullis-Growth Partners II, LLC is deemed to beneficially own 105,453 shares of the Issuer’s common stock.  James L.L. Tullis, in his individual capacity, beneficially owns 54,540 shares of the Issuer’s common stock and is a principal of each of the foregoing entities and may be deemed to possess voting and investment control over, and may be deemed to have an indirect beneficial ownership with respect to the shares held by Tullis-Dickerson Capital Focus III, L.P., Tullis Growth Fund, L.P., and Tullis Growth Fund II, L.P.

Pursuant to Rule 13d-4 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), the Reporting Persons declare that filing this Schedule 13G shall not be construed as an admission that any such person is, for the purposes of Section 13(d) and/or Section 13(g) of the Exchange Act, the beneficial owner of any Common Stock covered by this Schedule 13G except to the extent of such person’s direct ownership of such Common Stock, and except to the extent of such direct ownership, such beneficial ownership is expressly disclaimed by each Reporting Person.

(b)

Percent of class:   

i.                                          Tullis-Dickerson Capital Focus III, L.P.:  9.7%

ii.                                       Tullis-Dickerson Partners III, L.L.C.:  9.7%

iii.                                    Tullis Growth Fund, L.P.:  6%

iv.                                   Tullis-Growth Partners, L.L.C.:  6%

v.                                      Tullis Growth Fund II, L.P.: 08%

vi.                                   Tullis-Growth Partners II, L.L.C., 0.8%

vii.                                James L. L. Tullis:  16.6% as a principal of each of the foregoing entities and 0.4%, individually

The calculations of beneficial ownership percentages are based on 12,560,990 shares of common stock outstanding as of November 8, 2019, as reported by the Issuer in its Form 10-Q filed with the Securities and Exchange Commission on November 12, 2019.

(c)

Number of shares as to which the person has:

See row 5 of the cover page of each Reporting Person.

(i)

Sole power to vote or to direct the vote   

See row 6 of the cover page of each Reporting Person.

(ii)

Shared power to vote or to direct the vote    

See row 7 of the cover page of each Reporting Person.

(iii)

Sole power to dispose or to direct the disposition of   

See row 8 of the cover page of each Reporting Person.

(iv)

Shared power to dispose or to direct the disposition of   

Item 5.

Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following   o.

Not applicable.

Item 6.

Ownership of More than Five Percent on Behalf of Another Person

Not applicable.

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person

Not applicable.

Item 8.

Identification and Classification of Members of the Group

Not applicable.

Item 9.

Notice of Dissolution of Group

Not applicable.

Item 10.

Certification

Not applicable.

February 14, 2020

Date

TULLIS-DICKERSON CAPITAL FOCUS III, L.P.

By:

Tullis-Dickerson Partners III, L.L.C., its general partner

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS GROWTH FUND, L.P.

By:

Tullis-Growth Partners, L.L.C., its general partner

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS GROWTH FUND II, L.P.

By:

Tullis-Growth Partners II, L.L.C., its general partner

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS-DICKERSON PARTNERS III, L.L.C.

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Chief Executive Officer

TULLIS-GROWTH PARTNERS, L.L.C.

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS-GROWTH PARTNERS II, L.L.C.

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Chief Executive Officer

/s/ James L.L. Tullis

JAMES L.L. TULLIS, Individually

ATTENTION

Intentional misstatements or omissions of fact constitute Federal Criminal Violations (See 18 U.S.C. 1001).

TULLIS-DICKERSON CAPITAL FOCUS III, L.P.

By:

Tullis-Dickerson Partners III, L.L.C., its general partner

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS-DICKERSON PARTNERS III, L.L.C.

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS GROWTH FUND, L.P.

By:

Tullis-Growth Partners, L.L.C., its general partner

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS-GROWTH PARTNERS, L.L.C.

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS GROWTH FUND II, L.P.

By:

Tullis-Growth Partners II, L.L.C., its general partner

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Manager

TULLIS-GROWTH PARTNERS II, L.L.C.

By:

/s/ James L.L. Tullis

Name:

James L.L. Tullis

Title:

Chief Executive Officer

/s/ James L.L. Tullis

JAMES L.L. TULLIS, Individually