“When you hear hoofbeats, think horses not zebras,” is a saying well known to young doctors to remind them to think of the most common and likely diagnosis when assessing a patient. However, if a clinician is not that familiar with rare conditions, they may struggle to treat the horse when they should have diagnosed a zebra all along.
It is thought that around 350 million people are affected by undiagnosed genetic diseases, outnumbering people living with cancer and...