Exhibit A JOINT FILING AGREEMENTA Joint Filing Agreement • December 11th, 2008 • Biotechnology Value Fund L P • Investment advice
In accordance with Rule 13d-1(k)(l)(iii) under the Securities Exchange Act of 1934, as amended, the persons named below agree to the joint filing on behalf of each of them that certain Amendment No. 3 to the Statement on Schedule 13D filed on October 23, 2008 (including additional amendments thereto) with respect to the shares of Common Stock of Avigen, Inc. This Joint Filing Agreement shall be filed as an Exhibit to such Statement.
