Sex differences in the incidence of orofacial clefts and the question of primary prevention in families with genetic risk.

Systematic registration of all children with orofacial clefts in Bohemia (Czech Republic) started at the Clinic of Plastic Surgery, Prague in 1964. A sample of 181 affected children with positive family histories (i.e. one of the parents had some type of orofacial cleft) was selected for the present study. The aim of this study was to follow the relation not only between the type of cleft in the child and in its parent, but also between the sex of the child and of the affected parent. Among children of mothers with cleft lip 68% were boys and only 32% were girls with cleft lip or cleft lip and palate. If the mother had cleft lip and palate, the same cleft type was found in 64% of boys and only 15% of girls. If the mother had cleft palate, the same cleft type was found in 37% of boys and 51% of girls. Very similar results were found for affected fathers and their children, with only one exception: among children of fathers with cleft lip and palate, the percentage of boys and girls with CLP was 43% and 40%, respectively. We can conclude that the cleft type in a child depends not only upon the cleft type present in the mother or father, but also upon the sex of the child. There was higher risk to have the orofacial cleft in sons of mothers with CL or CLP or fathers with CL and daughters of mothers or fathers with CP. The combination of the preconception choice of the sex of the baby with the ultrasonography method for the prenatal screening of malformations could decrease the risk delivering a child with an orofacial cleft in families with a genetic predisposition.