We were pleased to gather all team members at the Institut Necker – Enfants Malades (INEM) on Mach 2nd 2020 to launch out the RHU COSY project. It was a very enthusiastic and productive meeting where we had the opportunity to make introductions, present the work packages, and get to know each other’s roles on the project. Other practical aspects such as context, overall goals, and timelines were discussed. We all have started working towards a common goal of transforming the outcome and the medical care of patients with overgrowth syndromes and we will keep you updated on the progress and the upcoming events of the project.