Causal Variations at IRF6 Gene Identified in Van der Woude Syndrome Pedigrees

The purpose of this study is to analyze the clinical characteristics of patients with Van der Woude syndrome (VWS) and to detect variations in each patient. Finally, the combination of genotype and phenotype can make a clear diagnosis of VWS patients with different phenotype penetrance.

Five Chinese VWS pedigree were enrolled. Whole exome sequencing of the proband was performed, and the potential pathogenic variation was further verified by Sanger sequencing in the patient and their parents. The human mutant IRF6 coding sequence was generated from the human full-length IRF6 plasmid by site-directed mutagenesis and cloned into the GV658 vector, RT-qPCR and Western blot were used to detect the expression of IRF6.

We found one de novo nonsense variation (p. Gln118Ter) and three novel missense variations (p. Gly301Glu, p. Gly267Ala, and p. Glu404Gly) co-segregated with VWS. RT-qPCR analysis revealed that p. Glu404Gly significantly reduced the expression level of IRF6 mRNA. Western blot of cell lysates confirmed that IRF6 p. Glu404Gly abundance levels were lower than those for IRF6 wild type.

This discovery of the novel variation (IRF6 p. Glu404Gly) expands the spectrum of known variations in VWS in Chinese humans. Genetic results combined with clinical phenotypes and differential diagnosis points from other diseases can make a definitive diagnosis and provide genetic counseling for families.