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TUBB3 gene

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

TUBB3 gene

The TUBB3 gene provides instructions for making a protein essential for the structure and function of nerve cells, and mutations in this gene are linked to several neurological and developmental disorders.

Normal Function

The TUBB3 gene provides instructions for making one version of a protein called beta-tubulin (β-tubulin). This protein is part of the tubulin family of proteins that form and organize cell structures called microtubules. Microtubules are rigid, hollow fibers that make up the cell's structural framework (the cytoskeleton). They are composed of β-tubulin and a similar protein called alpha-tubulin (α-tubulin) that is produced from a different gene. Microtubules grow and shrink as tubulin proteins are added to and removed from the ends of fibers, a process that allows cells to move and change shape.

β-tubulin produced from the TUBB3 gene is found in nerve cells (neurons) in the brain. This protein plays a role in the growth of specialized nerve cell extensions called axons and dendrites (collectively called neurites). Studies show this protein is particularly important for the regrowth of neurites after injury. Neurites relay messages to and from the brain to control muscle movement and detect sensations.

In addition to their role in cell movement, microtubules also function as a track along which other proteins, called motor proteins, transport materials within cells. β-tubulin produced from the TUBB3 gene appears to be important in the attachment of motor proteins to microtubules.

Health Conditions Related to Genetic Changes

Congenital fibrosis of the extraocular muscles

More than 10 mutations in the TUBB3 gene can cause congenital fibrosis of the extraocular muscles (CFEOM). These mutations most commonly cause a form of the condition called CFEOM3, and they are a rare cause of another form called CFEOM1. Individuals with any form of CFEOM are unable to move their eyes normally; they have difficulty looking upward or, less commonly, side-to-side, and most also have droopy eyelids (ptosis). In addition, people with CFEOM3 can have intellectual disability; behavioral, social, or language problems; or other neurological problems.

The TUBB3 gene mutations that cause CFEOM change single protein building blocks (amino acids) in the β-tubulin protein. The altered proteins assemble into microtubules, although some do so more readily than others. Research shows that when more altered β-tubulin protein is incorporated into microtubules, the signs and symptoms of the condition are more severe.

Microtubules made with altered β-tubulin proteins do not grow and shrink as they should, which prevents neurite growth. Cranial nerves that control muscles surrounding the eyes (extraocular muscles) are particularly affected, although other nerves can also be involved. Abnormal growth of cranial nerves impairs the function of extraocular muscles, leading to the characteristic features of CFEOM. Researchers suspect that abnormal growth of neurites within the brain leads to brain abnormalities that underlie intellectual disability and other neurological problems in some people with CFEOM3.

Certain mutations in the TUBB3 gene also appear to prevent motor proteins from attaching to microtubules. These mutations typically cause severe CFEOM3 that is associated with additional neurological problems, such as pain, weakness, or a decreased ability to feel sensations in the limbs (peripheral neuropathy) that begins in childhood or adulthood.

Polymicrogyria

Mutations in the TUBB3 gene are associated with polymicrogyria.

Other disorders

Mutations in the TUBB3 gene can also cause a condition called cortical dysplasia, complex, with other brain malformations 1 (CDCBM1). The brain abnormalities associated with this condition lead to intellectual disability, weak muscle tone (hypotonia), and progressive muscle stiffness (spasticity). Brain malformations in CDCBM1 result from abnormal development of the surface of the brain (the cortex) and other regions such as the basal ganglia, the corpus callosum, and the brainstem. Affected individuals do not typically have problems with the extraocular muscles as in CFEOM. It is thought that mutations in the TUBB3 gene disrupt the movement of neurons and axons to their correct locations, altering brain development.

Other Names for This Gene

  • class III beta-tubulin
  • Tubulin, Beta 3 Class III Gene
  • TUBULIN, BETA, CLASS III
  • TUBULIN, BETA-3

Frequently Asked Questions

CFEOM usually causes severe, non‑progressive restriction of upward gaze, leading to a downward‑pointing eye (hypotropia). Affected children often have limited ability to move the eyes vertically, may develop compensatory head tilts, and can have ptosis (drooping eyelid). Horizontal eye movements are usually less affected.
Testing is performed by sequencing the TUBB3 gene from a blood or saliva sample. Genetic testing is recommended when a child presents with CFEOM, especially if there is a family history of eye movement disorders, facial weakness, or peripheral neuropathy. Early confirmation helps with counseling and management planning.
Most pathogenic TUBB3 variants are inherited in an autosomal dominant pattern, meaning each child has a 50 % chance of inheriting the mutation. However, some cases arise de novo (new mutation) with no recurrence risk for siblings. Parental testing clarifies inheritance.
Management typically involves strabismus surgery to reposition the affected eye muscles and improve alignment, often combined with ptosis repair. Early intervention with vision therapy, glasses for refractive errors, and low‑vision aids can maximize visual development. Regular follow‑up with a pediatric ophthalmologist is essential to monitor ocular health and adjust treatment.
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.