Each month, Clinical Pharmacology & Therapeutics focuses on a particular theme. Twice a year, the associate editors, editors, and staff get together to discuss journal business and spend time setting up the calendar of themes. Often, there are no experts among us to take on a particular topic that we have chosen. The consequence is that one or two of us take on the theme and then have a crash course to learn as much as they can about it in order to solicit meaningful articles. This month's theme on rare diseases is such a case.