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Craniofrontonasal syndrome (CFNS) is an X-linked developmental disorder that shows paradoxically greater severity in heterozygous females than in hemizygous males. Females have frontonasal dysplasia and coronal craniosynostosis (fusion of the coronal sutures); in males, hypertelorism is the only typical manifestation. Here, we show that the classical female CFNS phenotype is caused by heterozygous loss-of-function mutations in EFNB1, which encodes a member of the ephrin family of transmembrane ligands for Eph receptor tyrosine kinases. In mice, the orthologous Efnb1 gene is expressed in the frontonasal neural crest and demarcates the position of the future coronal suture. Although EFNB1 is X-inactivated, we did not observe markedly skewed X-inactivation in either blood or cranial periosteum from females with CFNS, indicating that lack of ephrin-B1 does not compromise cell viability in these tissues. We propose that in heterozygous females, patchwork loss of ephrin-B1 disturbs tissue boundary formation at the developing coronal suture, whereas in males deficient in ephrin-B1, an alternative mechanism maintains the normal boundary. This is the only known mutation in the ephrin/Eph receptor signaling system in humans and provides clues to the biogenesis of craniosynostosis.

Original publication

DOI

10.1073/pnas.0402819101

Type

Journal article

Journal

Proc Natl Acad Sci U S A

Publication Date

08/06/2004

Volume

101

Pages

8652 - 8657

Keywords

Agenesis of Corpus Callosum, Amino Acid Sequence, Animals, Base Sequence, Chromosomes, Human, X, Cleft Lip, Cleft Palate, Cranial Sutures, Craniofacial Abnormalities, DNA, DNA Mutational Analysis, Dosage Compensation, Genetic, Ephrin-B1, Female, Genetic Linkage, Humans, Hypertelorism, Male, Mice, Molecular Sequence Data, Mutation, Nose, Pedigree, Sequence Homology, Amino Acid, Syndrome, Thumb