This study has been prepared with the support of the Rockefeller Foundation. A first draft was extensively reviewed by Catherine Monagle, who also undertook the final editing of the study. The author is also thankful for the comments made on the first draft by Graham Dutfield, Kelly P. Bannister, Gerry Bodeker, Xiaouri Zhang, Anthony Taubman, Jo Render, Robert Lettington, and Russell Barsh.

A review was also conducted by a group of experts convened by WHO, which met in New York on October 23, 2001, composed of Jerome Reichman, Catherine Monagle, Trevor Cook, Robert Weissman, German Velasquez, Xiaorui Zhang, Russell Barsh, Anthony So and the co-ordinator of the project, Carolyn Deere. The author, however, is solely responsible for the opinions contained in the study.