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SMARCA2 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SMARCA2 gene

The SMARCA2 gene provides instructions for creating a subunit of the SWI/SNF protein complex, which is essential for regulating gene expression through chromatin remodeling.

Normal Function

The SMARCA2 gene provides instructions for making one subunit of a group of protein complexes known as SWI/SNF complexes. These complexes regulate gene activity by a process called chromatin remodeling. Chromatin is the network of DNA and proteins that packages DNA into chromosomes. By moving parts of chromatin called nucleosomes, SWI/SNF complexes make DNA more accessible for gene expression. The SMARCA2 protein utilizes a molecule called ATP to provide the energy required for this remodeling process.

SWI/SNF complexes are involved in critical cellular processes, including:

  • Repairing damaged DNA
  • Replicating DNA
  • Controlling the growth, division, and maturation (differentiation) of cells

The SMARCA2 protein and other SWI/SNF subunits are thought to act as tumor suppressors, preventing cells from growing or dividing in an uncontrolled manner.

Health Conditions Related to Genetic Changes

Nicolaides-Baraitser syndrome

At least 50 mutations in the SMARCA2 gene have been linked to Nicolaides-Baraitser syndrome. These mutations typically change single amino acids in the protein, specifically within the area that attaches to ATP. While these altered proteins can still form SWI/SNF complexes, the complexes are nonfunctional and cannot perform chromatin remodeling. This disruption leads to the diverse signs and symptoms of the syndrome, which include:

  • Sparse scalp hair
  • Small head size (microcephaly)
  • Distinctive facial features
  • Short stature
  • Abnormal fingers
  • Recurrent seizures (epilepsy)
  • Moderate to severe intellectual disability with impaired language development

Cancers

Common DNA variants (polymorphisms) in the SMARCA2 gene have been associated with certain cancers, particularly lung cancer in tobacco smokers and head and neck cancer. These changes occur in the promoter region, which controls the production of the SMARCA2 protein. When both specific polymorphisms are present in both copies of the gene, they impair the promoter's function and reduce SMARCA2 gene expression. This reduction likely disrupts the regulation of cell growth and differentiation, potentially leading to cancer.

Frequently Asked Questions

Common polymorphisms in SMARCA2 have been linked to modestly higher risk of smoking‑related lung cancer, but they are not strong enough to warrant special screening beyond standard guidelines. If you are a smoker or have other risk factors, follow age‑appropriate low‑dose CT lung‑cancer screening recommendations.
Diagnosis is made by sequencing the SMARCA2 gene to identify a pathogenic missense mutation, most commonly in the ATP‑binding helicase domain. A positive result, together with the characteristic clinical features, confirms the syndrome.
Multidisciplinary care is key: early intervention speech and language therapy, occupational therapy for fine‑motor skills, physical therapy for gait and posture, and individualized education plans. Seizure control with antiepileptic drugs and behavioral support for autism‑like features are also commonly needed.
SMARCA2 mutations are typically autosomal‑dominant with high penetrance, but milder or subclinical presentations can occur. Genetic counseling can discuss recurrence risk (50 % for each child), options for prenatal or pre‑implantation testing, and the possibility of subtle neurodevelopmental issues that may benefit from early monitoring.
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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