Rare diseases are defined as those which affect fewer than 200,000 people in the United States. Despite advancements in rare disease research and development due to incentives created in the Orphan Drug Act more than 40 years ago, many rare diseases still lack effective treatments due to the complex science and limited market incentives involved in their development. Of the 10,000+ known rare diseases, just 5% have an FDA-approved treatment. Incubate's Rare Disease Investment Tracker measures the impacts of a challenging policy environment on rare disease R&D and notes where passage of policies like the ORPHAN Cures Act have had a positive impact.