Kosaki and Penttinen syndromes are extremely rare genetic conditions that cause serious problems in multiple organs, including the brain, bones, and blood vessels. Since 2019, an international team of doctors and researchers has been working together to better understand and treat these conditions. They have created shared care guidelines, a global patient database, and are studying whether a type of medicine called tyrosine kinase inhibitors (TKIs) might help. So far, over 25 patients have been identified worldwide, and some have already received this treatment. This collaborative effort helps improve care and research where traditional clinical trials are not possible. (By Pr Laurence FAIVRE, https://jmg.bmj.com/content/early/2025/07/24/jmg-2024-110600 )