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Condition report · Neurological

CTNNB1 Syndrome

Whole genome sequencing reads the CTNNB1 gene for the change in one copy that causes CTNNB1 syndrome, a condition with developmental delay, intellectual disability and stiffness in the legs.

A condition report looks for rare variants known to cause the conditions it covers.

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About this condition

A neurodevelopmental condition causing developmental delay, intellectual disability and leg stiffness, often with a small head size, and in some people changes in the blood vessels of the retina. It results from a change in one copy of the CTNNB1 gene.

CTNNB1 syndrome is a neurodevelopmental condition. Developmental delay and intellectual disability are typical, with low muscle tone in the trunk and stiffness of the legs. Small head size, behavioural differences and strabismus, a squint, are common.

It is caused by a change in one copy of CTNNB1, which encodes beta-catenin. This protein has key roles in the development of the brain and of retinal blood vessels. In up to 39% of reported people there are abnormal retinal blood vessels, and less often there is retinal detachment or vision loss.

Changes typically arise new, and rarely they are inherited from a parent. There is no curative treatment, but supportive care by a team that may include a neurologist, speech-language pathologist, physiotherapist and developmental paediatrician helps. Regular retinal examination by an eye specialist is important.

The condition we analyse

Autosomal dominant

Caused by changes in one copy of the CTNNB1 gene (beta-catenin); beta-catenin has key roles in brain and retinal blood vessel development. Changes typically arise de novo, and rarely are inherited from a parent.

Signs and symptoms

Developmental delay and intellectual disability are typical, with low muscle tone in the trunk and stiffness of the legs. Small head size and behavioural differences are common. In up to 39% of people there are abnormal retinal blood vessels (exudative vitreoretinopathy), and strabismus is common. Less often there is retinal detachment or vision loss.

What a diagnosis changes

Regular retinal examination by an eye specialist is important. Physiotherapy, orthotics, speech and educational support are central. Cases typically arise de novo, but genetic counselling and parental testing help clarify recurrence risk.

Genes analysed

Includes 2 related subtypes ↓
  • exudative vitreoretinopathy 7
  • severe intellectual disability-progressive spastic diplegia syndrome
MONDO:0100571Sources: [1][3][2]

Why whole genome sequencing

Most CTNNB1 changes arise new, and genetic counselling and parental testing help clarify recurrence risk. Whole genome sequencing reads the CTNNB1 gene.

Regular eye examinations matter

Abnormal retinal blood vessels occur in up to 39% of reported people, and strabismus is common. Regular retinal examination by an eye specialist is important, because retinal detachment and vision loss can occur less often.

Supportive care is central

There is no curative treatment, so care focuses on physiotherapy, orthotics, speech and educational support. Monitoring neurological findings helps check how well these supports work and whether new concerns about development or behaviour arise.

References

  1. Ho SKL, Tsang MHY, Lee M, Cheng SSW, Luk HM, Lo IFM et al., 2022. CTNNB1 Neurodevelopmental Disorder. GeneReviews
  2. CTNNB1 gene. MedlinePlus Genetics
  3. Familial exudative vitreoretinopathy. MedlinePlus Genetics

Other neurological conditions

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