The Van der Woude syndrome (dominantly inherited lip pits and clefts)

Abstract

A patient with symmetrical lower lip pits with or without cleft lip or palate is most likely to be the carrier of a dominant gene that causes the syndrome of lip pits and clefts or Van der Woude syndrome. Burdick et al, from data from 864 cases, calculated a mutation rate of about 1.8 x 10-5. In Zurich, Klausler found that about half of the probands ascertained through clefts represented fresh mutations. In Finland, Rintala and Ranta estimated the incidence of gene carriers among livebirths to be 1 in 33 600 with a prevalence in the general population of about 1 in 60 000 (about 2% of all clefts are associated with lower lip pits, the incidence of all clefts is about 1 in 650, and about 70 to 80% of patients carrying the Van der Woude gene have some kind of cleft). The 2% association of clefts with pits is higher than suggested in previous studies, but this probably reflects better ascertainment of cases with microforms of pits. The cardinal feature present in over 80% of carriers of the gene is symmetrical pits or eminences in the vermilion border of the lower lip about 1/2 cm from the midline. The pits are localised at the end of a canal 1 mm to 2.5 cm in length, which runs through the orbicularis oris muscle and may contain heterotopic salivary glands. The pits may be asymmetrical due to alteration of lip morphology or asymmetrical size or both. These pits are associated with clefts in about half of the gene carriers. Among these, two-thirds have cleft lip or cleft lip and palate and one-third have cleft palate alone. Hypodontia is present in about 10 to 20% of gene carriers (third molars excluded) and may occasionally represent the sole expression of the gene. The second incisors and second molars are mostly affected in the deciduous or permanent teeth or both.