A novel EFNB1 mutation in a patient with craniofrontonasal syndrome and right hallux duplication

•CFNS is a rare X-linked dominant developmental disorder.•EFNB1 is the only gene in which mutation is known to cause CFNS.•We describe 402 T > C, a novel de novo mutation on EFNB1•Broad hallux, a rare finding was present in this case with CFNS

Craniofrontonasal syndrome (CFNS, MIM #304110) is a rare X-linked dominant developmental disorder that shows paradoxically greater severity in affected females than in affected males. Our female patient with frontonasal dysplasia, craniosynostosis and additional malformations was consistent with CFNS. EFNB1, which encodes a member of the ephrin family of transmembrane ligands for Eph receptor tyrosine kinases, is the only gene in which mutation is known to cause CFNS. Here, we describe 402 T > C, a novel de novo mutation on EFNB1. This mutation results in substitution of highly conserved isoleucine at 134th residue to threonine.