Our aim is to better determine the spectrum of clinical manifestations, natural history, and underlying pathomechanisms of MED13L syndrome (Asadollahi-Rauch syndrome) for its better diagnosis and management. We are collecting clinically well-characterized patients with de novo copy number or sequence variants affecting MED13L and assembling an international network of patients. We are also biobanking fibroblast cells (derived from skin) of patients for experimental studies. Based on our findings, we hope to better characterize the syndrome and plan further studies for the discovery of underlying pathomechanisms and affected biological pathways as the prerequisite for targeted therapy.