IRF6 and van der Woude syndrome: Pathogenic variants in IRF6 are among the most common genetic causes of cleft lip and/or palate (CL/P) [17] and are associated with both Van der Woude syndrome (VWS, OMIM 119300) and Popliteal Pterygium syndrome (PPS, OMIM 119500), autosomal dominant Mendelian disorders with variable penetrance and expressivity that are characterized by CL/P and skin abnormalities [12].