Oral clefts and van der Woude syndrome

Hypodontia is a very common dental anomaly in patients with oral and facial clefts. The prevalence of hypodontia increases with cleft severity, and varies between populations. Prevalence of hypodontia ranges from 10% to 68% in different cleft types in Finland, being 10% in cleft lip, 33% in cleft palate, 49% in unilateral, and 68% in bilateral cleft lip and palate groups, and even higher in twins with clefts (Ranta, 1986; Laatikainen et al, 1994). The upper lateral incisor is the most frequently affected tooth in the cleft area both in primary and permanent dentitions. Hypodontia is more common than in the normal population also outside the cleft region, where the upper and lower second premolars are most frequently missing. A higher incidence of hypodontia in the maxilla has been reported, and has been suggested to be a result of the same factors as for the cleft (Ranta et al, 1988). If the permanent lateral incisor is present on the cleft side it usually shows abnormalities in size and shape. In addition, the dimensions of other teeth are smaller, and timing of tooth formation and eruption in cleft children is delayed (Ranta, 1986).

In Pierre Robin sequence with cleft palate, micrognathia, and glossoptosis, a 50% prevalence of hypodontia, excluding the third molars, has been reported. Hypodontia in the mandible is more frequent in Pierre Robin patients than in that of the cleft patients (Ranta, 1986).

Even higher prevalence of hypodontia (69%) has been shown in patients with the autosomal dominant Van der Woude syndrome associated with cleft lip and/or palate and pits of the lower lip. Mutations in the IRF6 (interferon regulatory factor 6) gene in has been reported 1q32-41 in families with van der Woude or popliteal pterygium syndromes (Kondo et al, 2002). The mutations included missense, nonsense and indel-mutations. The authors suggested that loss-of-function mutations typically cause Van der Woude syndrome whereas missense mutations of the residues that directly interact with DNA cause a more severe phenotype of popliteal pterygium syndrome through a dominant-negative mechanism. Genetic heterogeneity in Van der Woude syndrome has been suggested and linkage to another region of chromosome 1 has been reported (Koillinen et al, 2001).

Text partially adapted from Sirpa Arte: Phenotypic and genotypic features of familial hypodontia. Dissertation, Institute of Dentistry, University of Helsinki, Finland, 2001.


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Text last edited 07.10.2003 by P.N. , page last created 10.12.2004 by P.N.