Two decades of orphan product development.

Over the past 20 years, incentives of the Orphan Drug Act (ODA), the largest single source of extramural clinical grants at the US Food and Drug Administration, have had a substantial impact on public health. ODA incentives have contributed to the development of many innovative biotechnology products, and as our understanding of the human genome evolves, it is anticipated that pharmacogenomics will result in the identification of more 'orphan diseases'.