The van der Woude syndrome in a large kindred: variability, penetrance, genetic risks.

The van der Woude syndrome was studied in a seven-generation kindred. Lip pits were the most common manifestation of affected persons. They occurred in 88% of the affected and were the only manifestations in 64%; clefts of lip and palate occurred in 21%. Penetrance was 96.7%. Careful examination showed minor manifestations of the syndrome in several individuals who had considered themselves unaffected. The distribution of manifestations and the risk to off-spring differed appreciably from that reported in the literature. The implications of these findings for genetic counseling are discussed.