A Bayesian method for the estimation of penetrance: application to mandibulofacial and frontonasal dysostoses.

We describe a Bayesian method of estimating penetrance from genealogical data. It consists of calculating the likelihood of the data alone to make inferences about penetrance without sample space considerations. The method is applied to mandibulofacial dysostosis giving a penetrance of 0.908 with 0.95 credible interval of [0.809; 0.972] and to frontonasal dysostosis giving a penetrance of 0.670 with 0.95 credible interval of [0.457; 0.851].