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.