Clinical teaching dictates that isolated unicoronal synostosis is sporadic in 
occurrence and is possibly related to intrauterine constraint. Despite this, 
isolated reports document a familial occurrence. It has previously been 
recognized that there may be a familial pattern of inheritance. Recently, 
mutations in fibroblast growth factor receptors (FGFRs) have been implicated in 
several syndromic craniosynostoses. At the authors' institution, mutations in 
FGFR3, located at chromosome 4p16, have been found to cause coronal synostosis. 
Two cases of unicoronal synostosis were found to have the same Pro250Arg 
missense mutation in FGFR3. This finding suggested that all patients with a 
diagnosis of unicoronal synostosis be screened for the FGFR3 mutation. Between 
January and December of 1996, patients with a diagnosis of plagiocephaly at the 
Children's Hospital of Philadelphia were evaluated for the FGFR3 mutation. 
Thirty-seven patients with unicoronal synostosis had mutational studies. Two 
additional patients were known to have the FGFR3 mutation at the onset of the 
study. Of the 37 patients screened, four were found to have the FGFR3 mutation, 
for a total of six patients with both unicoronal synostosis and the FGFR3 
mutation. All patients with unicoronal synostosis were evaluated for facial 
dysmorphology and operative outcome. The six patients with the FGFR3 mutation 
had more severe cranial dysmorphology and were more likely to need surgical 
revision than those without the FGFR3 mutation. The occurrence of the FGFR3 
mutation among patients with unicoronal synostosis provides evidence for a 
genetic basis of certain forms of plagiocephaly. The clinical, radiologic, and 
molecular findings will be an important addition to the surgical management and 
counseling of patients with unicoronal synostosis.