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EFNB1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

EFNB1 gene

The EFNB1 gene provides instructions for making the ephrin B1 protein, which is critical for cell adhesion and communication during the development of tissues and organs.

Normal Function

The EFNB1 gene provides instructions for making a protein called ephrin B1. This protein spans the membrane that surrounds the cell. The portion outside the cell attaches (binds) to proteins called Eph receptor kinases on the surface of neighboring cells. Together, these proteins form Eph/ephrin complexes, which help cells stick to one another (cell adhesion) and communicate. Communication between the attached cells plays a critical role in the normal shaping (patterning) of many tissues and organs before birth. In the brain, Eph/ephrin complexes also play a part in the development of nerve cells (neurons) and in the ability of the connections between neurons (synapses) to change and adapt over time in response to experience (synaptic plasticity).

Health Conditions Related to Genetic Changes

Craniofrontonasal syndrome

More than 115 mutations in the EFNB1 gene have been found to cause craniofrontonasal syndrome. This rare condition is characterized by the premature closure of certain bones of the skull (craniosynostosis) during development, which affects the shape of the head and face. Females with craniofrontonasal syndrome typically have more severe signs and symptoms than affected males, who often have one or two features of the condition.

Mutations in the EFNB1 gene result in a shortage (deficiency) of ephrin B1 protein. Most of these mutations lead to an abnormally short version of the molecule that acts as the genetic blueprint used to make the ephrin B1 protein. The shortened molecules are quickly broken down before protein can be produced. A deficiency of ephrin B1 protein prevents the adhesion and communication between cells that aids in proper development, which disrupts normal patterning in tissues before birth. Abnormal development of the skull and other facial structures leads to the signs and symptoms of craniofrontonasal syndrome.

Other Names for This Gene

  • EFL3
  • EFNB1 gene
  • ELK LIGAND
  • Elk-L
  • ELKL
  • EPH-RELATED RECEPTOR TYROSINE KINASE LIGAND 2
  • EPLG2
  • LIGAND OF EPH-RELATED KINASE 2

Frequently Asked Questions

coordinated team typically includes a pediatric craniofacial surgeon for skull reconstruction, a neurologist for developmental monitoring, an orthopedist for limb anomalies, a geneticist for counseling, and a speech/occupational therapist for feeding and motor skills. Regular ophthalmology and audiology exams are also important because vision and hearing problems are common.
EFNB1 is located on the X chromosome. In females, random X‑inactivation creates a mosaic pattern of cells that either express normal or mutant ephrin B1, leading to disrupted cell‑cell signaling and more pronounced tissue patterning defects. Males have only one X chromosome, so the single mutant allele usually results in a milder, sometimes limited, phenotype.
Key early clues include a broad nasal bridge, hypertelorism (wide‑set eyes), bifid nasal tip, low‑set or malformed ears, and premature closure of one or more skull sutures (craniosynostosis). Limb anomalies such as syndactyly (webbed fingers) or split hand/foot, as well as facial asymmetry, are also red flags.
Yes. If there is a known family mutation, chorionic villus sampling (10‑12 weeks) or amniocentesis (15‑18 weeks) can be used for targeted molecular testing. Prenatal ultrasound may also detect craniosynostosis or facial anomalies, prompting diagnostic testing.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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