Significant phenotypic variability of Muenke syndrome in identical twins.

Muenke syndrome (MS), also known as Muenke nonsyndromic coronal craniosynostosis, is an autosomal dominant condition which can be distinguished from the more common forms of acrocephalosyndactyly but presents a significant variable phenotype. We report on a set of identical twins with a de novo C749G mutation in the FGFR3 gene codon 250 after a pregnancy complicated by prenatal exposure to Nortriptyline. These patients illustrate the variable expressivity of MS in association with an identical gene mutation.