There are over 7,000 identified rare diseases, and while each of these is by definition rare, collectively they affect more than 300 million people globally, or around 4% of the world’s population. Yet just a fraction of rare diseases has an approved therapy, and efforts to develop safe, effective therapies are hampered by issues such as the tiny numbers of patients involved and our poor understanding of many rare diseases. This session will feature collaborative research model case studies on rare and orphan diseases from both sides of the Atlantic that are making practical contributions to the advancement of research and drug development in this highly challenging field.