In the fourth seminar in the series on register research, Daniel Olsson, Associate Professor at the Institute of Medicine and specialist in endocirinology at Sahlgrenska University Hospital. The lecture was about register studies on rare diagnoses and small patient groups, and discussed possibilities, design and pitfalls in the area. The seminar was held in Swedish and broadcast on Zoom. It was filmed, and you can watch the film in retrospect until May 18. Here you can see the recording:https://play.gu.se/media/Registerstudier+p%C3%A5+s%C3%A4llsynta+diagnoser/0_c7xgexks