IRF6 and cleft lip: Mutations of interferon regulatory factor 6 (IRF6), located on chromosome 1q32.2 (OMIM # 607199), is associated with the autosomal‐dominant Van der Woude syndrome, the most common Mendelian syndrome that has the cardinal signs of cleft lip with or without cleft palate (CL/P) and/or cleft palate only (CPO) with dental anomalies and pitted lips (Kondo et al., 2002; Rizos and Spyropoulos, 2004).