Genetic epidemiology and control of genetic expression in van der Woude syndrome.

By three pedigree and statistical criteria van der Woude syndrome (VWS) appears to have been underreported and frequently not diagnosed. Eight percent of gene carriers are not diagnosed because they are nonpenetrant. But among penetrant gene carriers as many as 80% may not have been recognized in the past. A direct estimate of incidence of VWS is 3.6/100,000 births; indirect estimates are more than double that. The relative risk of inheriting a cleft from an affected parent is 22.43%; the risk of inheriting lip pits only, or being nonpenetrant is 27.57%. (This corrects a similar statement in the abstract of Burdick et al [J Craniofacial Genet Dev Biol 5:181-208, 1985], which was incorrectly calculated). The idea of unitary control of the action of the VWS gene in the three target tissues appears not to be supported. Rather, we tend to support the idea that the gene is controlled independently in the three tissues. Indications of a family at risk are listed and discussed.