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SMC3 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SMC3 gene

The SMC3 gene encodes a protein that is a key component of the cohesin complex, playing a vital role in chromosome organization and cell development.

Normal Function

The SMC3 gene provides instructions for making a protein that is part of the structural maintenance of chromosomes (SMC) family. Within the nucleus, SMC proteins help regulate the structure and organization of chromosomes.

The protein produced from the SMC3 gene helps control chromosomes during cell division. Before cells divide, they must copy all of their chromosomes. The copied DNA from each chromosome is arranged into two identical structures, called sister chromatids, which are attached to one another during the early stages of cell division. The SMC3 protein is part of a protein group called the cohesin complex that holds the sister chromatids together.

Researchers believe that the SMC3 protein, as a structural component of the cohesin complex, also plays important roles in stabilizing cells' genetic information, repairing damaged DNA, and regulating the activity of certain genes that are essential for normal development.

Although the SMC3 protein is found primarily in the nucleus, some of this protein is transported out of cells. The exported protein, which is usually called bamacan, may be involved in sticking cells together (cell adhesion) and cell growth. Bamacan is a component of basement membranes, which are thin, sheet-like structures that separate and support cells in many tissues.

Health Conditions Related to Genetic Changes

Cornelia de Lange syndrome

At least 15 variants in the SMC3 gene have been found to cause Cornelia de Lange syndrome, a developmental disorder that affects many parts of the body. Researchers estimate that variants in this gene account for 1 to 2 percent of all cases of this condition.

Most of the SMC3 gene variants that cause Cornelia de Lange syndrome either change single protein building blocks (amino acids) in the SMC3 protein or add or delete a small number of amino acids in the protein. Each of these variants alters the structure and function of the protein, which likely interferes with the activity of the cohesin complex and impairs its ability to regulate genes that are critical for normal development. Although researchers do not fully understand how these changes cause Cornelia de Lange syndrome, they suspect that altered gene regulation probably underlies many of the developmental problems characteristic of the condition.

Studies suggest that variants in the SMC3 gene tend to cause a form of Cornelia de Lange syndrome with relatively mild features. Compared to variants in the NIPBL gene, which are the most common known cause of the disorder, SMC3 gene variants often cause less significant delays in development and growth and are less likely to cause major birth defects.

Other Names for This Gene

  • BAM
  • bamacan
  • basement membrane-associated chondroitin proteoglycan
  • BMH
  • chondroitin sulfate proteoglycan 6
  • chromosome-associated polypeptide
  • CSPG6
  • HCAP
  • SMC3_HUMAN
  • SMC3L1

Frequently Asked Questions

Genetic changes in the SMC3 gene are associated with Cornelia de Lange syndrome, a developmental disorder affecting many parts of the body. Key features often include distinctive facial characteristics, intellectual disability, growth delays, and abnormalities of the limbs, heart, or other organs.
Diagnosis of a genetic change in the SMC3 gene usually involves genetic testing, often through a blood sample. This testing looks for specific variants or mutations within the gene that are known to cause Cornelia de Lange syndrome, especially when clinical symptoms suggest the condition.
Cornelia de Lange syndrome caused by SMC3 gene changes can be inherited. The inheritance pattern depends on the specific genetic change, but often it can occur spontaneously (de novo) or be passed down in an autosomal dominant manner. Genetic counseling is highly recommended to understand the specific risks for future children and family members.
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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