A novel mutation, 1234del(C), of the IRF6 in a Thai family with Van der Woude syndrome.

Van der Woude syndrome (VWS) is an autosomal dominant disorder and the most common cleft syndrome characterized by cleft lip and palate with lip pits. Very recently, mutations in the interferon regulatory factor 6 gene (IRF6) were identified to cause VWS in patients of northern European descent. We describe a Thai family with VWS. The proband, an 8-month-old boy, had bilateral complete cleft lip and palate, and two conical elevations with lip pits on his lower lip. Four other family members had various manifestations of the clefts and lower lip pits. Mutation analysis of the proband and his mother for the entire coding region of IRF6 identified a novel mutation, 1234del(C), in its exon 9. The deletion is expected to result in some amino acid changes followed by truncation at amino acid 435. This observation supports that IRF6 is the gene responsible for VWS across different populations and that haploinsufficiency of the gene disturbs development of the lip and palate.