To assess the highly variable clinical consequences and treatments of Moesin deficiency, collect real world evidence about this ultra rare disease, and ultimately to improve patient management, Isabelle André, Jean-Sébastien Diana and coworkers in Paris are performing an international registry study (XMAID international registry NCT06278337). If you care for a MOESIN-deficient patient and want to participate, please contact   to participate in the study. Inclusion of new patients is possible till the end of 2024.