To determine whether the autosomal dominant fibroblast growth factor receptor 3 
(FGFR3) Pro250Arg mutation causes anterior plagiocephaly, patients with either 
apparently sporadic unicoronal synostosis (N = 37) or other forms of anterior 
plagiocephaly (N = 10) were studied for this mutation. Of 37 patients with 
unicoronal synostosis, 4 tested positive for the Pro250Arg mutation in FGFR3, 
and 33 were negative for this mutation. In three mutation positive patients with 
full parental studies, a parent with an extremely mild phenotype was found to 
carry the same mutation. None of the 6 patients with nonsynostotic plagiocephaly 
and none of the 4 patients with additional suture synostosis had the FGFR3 
mutation. Because it is impossible to predict the FGFR3 Pro250Arg mutation 
status based on clinical examination alone, all patients with unicoronal 
synostosis should be tested for it. To assess their recurrence risk, all parents 
of mutation positive patients should be tested regardless of their clinical 
findings, because the phenotype can be extremely variable and without 
craniosynostosis.