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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. 1)*

Genaera Corporation

(Name of Issuer)

Common Stock, par value $.002 per share

(Title of Class of Securities)

36867G100

(CUSIP Number)

December 31, 2006

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

o Rule 13d-1(b)

þ Rule 13d-1(c)

o Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).


CUSIP No.		36867G100		Page		2		of		8


1	NAMES OF REPORTING PERSONS: I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): RA Capital Management, LLC


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:

	Massachusetts

		5	SOLE VOTING POWER:

NUMBER OF			6,328,163

SHARES		6	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			0

EACH		7	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			6,328,163

WITH:		8	SHARED DISPOSITIVE POWER:

			0

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

	6,328,163

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):

	6.05%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):

	IA


CUSIP No.		36867G100		Page		3		of		8


1	NAMES OF REPORTING PERSONS: I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): Richard H. Aldrich


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:

	USA

		5	SOLE VOTING POWER:

NUMBER OF			0

SHARES		6	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			6,328,163

EACH		7	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER:

			6,328,163

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

	6,328,163

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):

	6.05%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):

	IN


CUSIP No.		36867G100		Page		4		of		8


1	NAMES OF REPORTING PERSONS: I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): Peter Kolchinsky


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:

	USA

		5	SOLE VOTING POWER:

NUMBER OF			0

SHARES		6	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			6,328,163

EACH		7	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER:

			6,328,163

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

	6,328,163

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):

	6.05%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):

	IN


CUSIP No.		36867G100		Page		5		of		8


1	NAMES OF REPORTING PERSONS: I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): RA Capital Biotech 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

		5	SOLE VOTING POWER:

NUMBER OF			6,328,163

SHARES		6	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			0

EACH		7	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			6,328,163

WITH:		8	SHARED DISPOSITIVE POWER:

			0

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

	6,328,163

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):

	6.05%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):

	PN

Page 6 of 8

Item 1.

(a) Name of Issuer: Genaera Corporation (the “Issuer”).

(b) Address of the Issuer’s Principal Executive Offices: 5110 Campus Drive, Plymouth Meeting, Pennsylvania.

Item 2.

(a) Name of Person Filing: This joint statement on Schedule 13G is being filed by Richard H. Aldrich, Peter Kolchinsky, RA Capital Management, LLC and RA Capital Biotech Fund, L.P., who are collectively referred to as the “Reporting Persons.” Mr. Aldrich and Mr. Kolchinsky (together, the “Managers”) are the managers of RA Capital Management, LLC (“Capital”), which is the sole general partner of RA Capital Biotech Fund, L.P. (the “Fund”). The Reporting Persons are parties to a Joint Filing Agreement dated October 5, 2006 relating to this Schedule 13G, a copy of which was previously filed with this Schedule 13G and is hereby incorporated by reference herein, pursuant to which the Reporting Persons have agreed to file this statement jointly in accordance with the provisions of Rule 13d-1(k) under the Act.

(b) Address of Principal Business Office: The principal business office of the Reporting Persons with respect to the shares reported hereunder is 111 Huntington Avenue, Suite 610, Boston, Massachusetts 02199.

(c) Citizenship: Capital is a Massachusetts limited liability company. The Fund is a Delaware limited partnership. The Managers are U.S. citizens.

(d) Title and Class of Securities: Common stock, par value $0.002 per share (“Common Stock”)

(e) CUSIP Number: 36867G100

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:

N/A

Item 4. Ownership

In the aggregate, the Reporting Persons beneficially own 6,328,163 shares of the Common Stock of the Issuer, representing 6.05% of such class of securities. The beneficial ownership of each Reporting Person is as follows: The Fund, Capital, as the sole general partner of the Fund, and Mr. Aldrich and Mr. Kolchinsky as the managers of Capital, each beneficially own 6,328,163 shares of the Common Stock of the Issuer representing 6.05% of the class. The percentage of the Common Stock beneficially owned by each Reporting Person is based on a total of 104,612,789 shares of the Common Stock of the Issuer outstanding as of November 9, 2006, as reported in the most recent quarterly report of the Issuer on Form 10-Q for the quarterly period ended September 30, 2006.

Page 7 of 8

The Fund has the power to vote and dispose of the shares of Common Stock beneficially owned by such Fund (as described above). Capital, as the sole general partner of the Fund, has the sole authority to vote and dispose of all of the shares of Common Stock reported in this Schedule 13G. The Managers, by virtue of their positions as managers of Capital, have the shared authority to vote and dispose of all of the shares of Common Stock reported in this joint statement Schedule 13G.

Item 5. Ownership of Five Percent or Less of a Class

N/A

Item 6. Ownership of More than Five Percent on Behalf of Another Person

N/A

Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person

N/A

Item 8. Identification and Classification of Members of the Group

N/A

Item 9. Notice of Dissolution of Group

N/A

Item 10. Certification

By signing below I hereby certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

Page 8 of 8

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.


		DATE: February 9, 2007

		RA CAPITAL BIOTECH FUND, L.P.

		By: RA Capital Management, LLC
		General Partner

		By: /s/ Richard H. Aldrich

		Richard H. Aldrich
		Manager

		RA CAPITAL MANAGEMENT, LLC

		By: /s/ Richard H. Aldrich

		Richard H. Aldrich
		Manager

		RICHARD H. ALRICH

		/s/ Richard H. Aldrich

		Richard H. Aldrich

		PETER KOLCHINSKY

		/s/ Peter Kolchinsky

		Peter Kolchinsky