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SMARCB1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SMARCB1 gene

The SMARCB1 gene provides instructions for a protein that acts as a tumor suppressor by regulating gene activity through chromatin remodeling.

Normal Function

The SMARCB1 gene provides instructions for making a subunit of SWI/SNF protein complexes. These complexes regulate gene activity through chromatin remodeling, a process that changes how tightly DNA is packaged into chromosomes. By regulating gene activity, these complexes are involved in DNA repair, DNA replication, and the control of cell growth, division, and maturation. The SMARCB1 protein is thought to act as a tumor suppressor, preventing cells from growing or dividing in an uncontrolled way.

Health Conditions Related to Genetic Changes

Coffin-Siris syndrome

Variants in the SMARCB1 gene can cause Coffin-Siris syndrome, characterized by delayed development, abnormalities of the fifth fingers or toes, and coarse facial features. These germline variants are thought to result in abnormal chromatin remodeling, which disrupts various cellular activities.

Rhabdoid tumor predisposition syndrome

Rhabdoid tumor predisposition syndrome (RTPS) is caused by germline variants in the SMARCB1 gene, which increase the risk of developing malignant rhabdoid tumors in the brain, spinal cord, or kidneys. A tumor develops when an additional somatic variant deletes the remaining normal copy of the gene in specific cells, leading to a total deficiency of the SMARCB1 protein.

Schwannomatosis

Variants in the SMARCB1 gene are associated with schwannomatosis, a disorder characterized by multiple noncancerous tumors (schwannomas) on nerves. These variants lead to the production of an altered protein with reduced function. It is believed that additional somatic variants are required for tumors to form, and some individuals with these variants may never develop tumors (reduced penetrance).

Other Cancers

Somatic variants in both copies of the SMARCB1 gene can cause noninherited (sporadic) rhabdoid tumors in children due to the loss of the protein's tumor suppressor function.

Other Names for This Gene

  • BAF47
  • BRG1-associated factor 47
  • INI1
  • Integrase interactor 1 protein
  • SNF5
  • SNF5 homolog
  • SNF5_HUMAN
  • SNF5L1

Genomic Location

The SMARCB1 gene is found on chromosome 22.

Frequently Asked Questions

SMARCB1 test typically requires a blood draw or a saliva sample for DNA extraction. For tumor testing, a fresh or formalin‑fixed, paraffin‑embedded (FFPE) tissue sample from the suspected tumor is used. The blood or saliva should be collected in a tube with an anticoagulant (e.g., EDTA) and processed within the lab’s specified time frame to preserve DNA integrity. For tumor samples, the pathologist will confirm that the tissue contains enough tumor cells (usually >20%) before sequencing.
Surveillance typically involves regular MRI scans of the brain, spine, and kidneys, starting in infancy and continuing through early childhood. A common schedule is a brain MRI every 3–6 months until age 3, then every 6–12 months until age 5, and annually thereafter. Renal ultrasounds are also performed annually. Early detection improves surgical and therapeutic outcomes.
germline SMARCB1 mutation is inherited in an autosomal dominant pattern, meaning each first‑degree relative has a 50 % chance of carrying the same variant. Genetic counseling is recommended for the patient and at least one parent (if age‑appropriate) to discuss testing, surveillance, and reproductive options. Cascade testing can identify at-risk relatives early, allowing for appropriate monitoring for rhabdoid tumors or schwannomatosis.
Yes, certain SMARCB1 variants are associated with schwannomatosis, which presents as multiple benign schwannomas on peripheral nerves. Management focuses on symptom control: pain management, physical therapy, and surgical removal of symptomatic or enlarging tumors. Regular neurologic exams and imaging (MRI) help monitor tumor growth. Genetic testing confirms the diagnosis and informs surveillance for other associated conditions.===
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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