The van der Woude syndrome is highly variable in its expression from person to person. There may be cleft lip, cleft palate, or both. The lip pits may be associated with accessory salivary glands that empty into the pits, leading to visible discharge.
The syndrome is inherited in an autosomal dominant manner. It is due to mutation of the IRF6 gene (interferon regulatory factor 6) on chromosome 1. The same gene is mutated in the popliteal pterygium syndrome, another disorder with cleft lip/palate and lip pits.