BACKGROUND: Muenke syndrome is a genetically determined craniosynostosis that 
involves one or both coronal sutures. In some patients it is associated with 
skeletal abnormalities such as thimble-like middle phalanges, coned epiphysis, 
and/or neurological impairment, namely sensorineural hearing loss or mental 
retardation. In spite of a variable phenotype, Muenke syndrome has been related 
to a unique mutation on the FGFR3 gene, Pro 250 to Arg, which is characteristic 
of this disease. Because of the incomplete penetrance of this anomaly, the 
suspicion of Muenke syndrome must be raised in any child with uni- or bilateral 
coronal craniosynostosis, and the genetic analysis propounded even in the 
absence of extracranial features.
ILLUSTRATIVE CASES: We report the cases of two sisters who presented with Muenke 
syndrome and whose affected mother did not have any form of craniosynostosis.