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RAD21 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

RAD21 gene

The RAD21 gene provides instructions for a protein that is a critical component of the cohesin complex, which organizes chromosomes during cell division.

Normal Function

The RAD21 gene provides instructions for making a protein involved in regulating the structure and organization of chromosomes during cell division. Before cells divide, they copy their chromosomes into two identical structures called sister chromatids. The RAD21 protein is part of the cohesin complex, which holds these sister chromatids together.

As a structural component of the cohesin complex, the RAD21 protein also plays important roles in:

  • Stabilizing genetic information
  • Repairing damaged DNA
  • Regulating the activity of genes essential for normal development

Health Conditions Related to Genetic Changes

Cornelia de Lange syndrome

Variants in the RAD21 gene have been identified in people with Cornelia de Lange syndrome, a developmental disorder. These variants can include deletions that remove the gene or mutations that impair the function of the RAD21 protein.

A defective or missing RAD21 protein alters the activity of the cohesin complex, impairing its ability to regulate genes critical for development. Studies suggest that RAD21 variants cause a form of the syndrome with relatively mild features, resulting in less significant developmental delays and growth issues compared to variants in the NIPBL gene.

Trichorhinophalangeal syndrome type II

The RAD21 gene is located in a region of chromosome 8 that is deleted in people with trichorhinophalangeal syndrome type II (TRPS II). Affected individuals are missing one copy of the RAD21 gene, leading to a reduced amount of RAD21 protein. This shortage may contribute to intellectual disability, though the deletion of other nearby genes likely contributes to the additional features of the condition, such as bone and joint malformations and distinctive facial features.

Other Names for This Gene

  • CDLS4
  • double-strand-break repair protein rad21 homolog
  • hHR21
  • HR21
  • HRAD21
  • KIAA0078
  • kleisin
  • MCD1
  • nuclear matrix protein 1
  • NXP-1
  • NXP1
  • RAD21 homolog
  • SCC1
  • SCC1 homolog
  • sister chromatid cohesion 1

Genomic Location

The RAD21 gene is found on chromosome 8.

Frequently Asked Questions

Yes. If a known RAD21 pathogenic variant is present in a parent, targeted prenatal testing (via chorionic villus sampling or amniocentesis) can look for the same change. Even without a known familial variant, chromosomal microarray or next‑generation sequencing can identify deletions that include RAD21. Prenatal testing is typically discussed when there is a known risk or a previous child with a confirmed RAD21‑related condition.
Haploinsufficiency (loss of one copy) of RAD21 contributes to the intellectual disability and growth issues seen in TRPS II, but the phenotype also reflects loss of neighboring genes. Management focuses on multidisciplinary care: regular growth monitoring, early intervention services (speech, occupational therapy), and educational support. Knowing RAD21 is involved helps anticipate potential DNA repair sensitivities, so clinicians may avoid unnecessary radiation exposure when possible.
Testing for RAD21 variants (including deletions, missense, or nonsense mutations) can confirm whether the mild form of CdLS in your child is due to a RAD21 alteration. A positive result clarifies the molecular cause, helps predict the likely severity of developmental issues, and provides accurate recurrence risk information for future pregnancies. If no RAD21 change is found, other CdLS‑related genes (e.g., NIPBL, SMC1A) may be evaluated.
Most pathogenic RAD21 changes that cause CdLS are inherited in an autosomal dominant pattern, meaning a parent who carries the mutation has a 50 % chance of passing it to each child. However, many cases arise de novo (new in the child). Parental testing can determine whether the variant is inherited or new, which directly informs recurrence risk.
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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