Van der Woude (VWS) and popliteal pterygium syndromes are caused by mutations in the interferon regulatory factor (IRF6) gene. Two Thai VWS families demonstrating newly recognized findings of VWS are reported. The phenotype in the first family includes sensorineural hearing loss, cleft lip and palate, lower lip anomalies, ankyloglossia, hypodontia, dental pulp stones, large craniofacial sinuses, and limb anomalies. Molecular analysis of IRF6 revealed an 11 bp deletion in exon 4. This frameshift mutation truncates IRF6 just after the DNA binding domain. The mutation implies that IRF6 can affect dental pulp calcification, pneumatization of craniofacial sinuses, and ear and limb development. The second family consists of an affected brother and sister. Both have lower lip anomalies and the sister has cleft lip and palate. Interestingly, both have abnormal shape of the mandibular deciduous and permanent molars. Mutation analysis of IRF6 was negative, suggesting that the mutations may be located outside of the coding exons or in another locus.
dental pulp stone, IRF6 gene, limb anomaly, hearing loss, Van der Woude syndrome