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RIT1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

RIT1 gene

The RIT1 gene provides instructions for a protein that helps cells survive stress and regulates cell growth and division as part of the RAS/MAPK pathway.

Normal Function

The RIT1 gene provides instructions for making a protein that helps cells survive during periods of cellular stress, such as unusually high energy demands. As part of a signaling pathway known as the RAS/MAPK pathway, the RIT1 protein relays signals from outside the cell to the cell's nucleus. These signals instruct the cell to grow and divide (proliferate) or to mature and take on specialized functions (differentiate).

The RIT1 protein is a GTPase, which means it converts a molecule called GTP into another molecule called GDP. To transmit signals during periods of cellular stress, the RIT1 protein is turned on by attaching (binding) to a molecule of GTP. The RIT1 protein is turned off (inactivated) when it converts the GTP to GDP. When the protein is bound to GDP, it does not relay signals to the cell's nucleus.

The RIT1 gene belongs to a class of genes known as oncogenes. When mutated, oncogenes have the potential to cause normal cells to become cancerous. The RIT1 gene is in the Ras family of oncogenes, which also includes KRAS, HRAS, and NRAS. These proteins play important roles in cell division, cell differentiation, and the self-destruction of cells (apoptosis).

Health Conditions Related to Genetic Changes

Noonan syndrome

At least 14 mutations in the RIT1 gene have been found to cause Noonan syndrome. This condition is characterized by mildly unusual facial characteristics, short stature, heart defects, bleeding problems, skeletal malformations, and many other signs and symptoms. People with Noonan syndrome caused by RIT1 gene mutations often have swelling caused by a buildup of fluid (lymphedema). Rarely, people with Noonan syndrome caused by a RIT1 gene mutation develop cancer, including a blood cancer called acute lymphoblastic leukemia.

The RIT1 gene mutations associated with Noonan syndrome change single protein building blocks (amino acids) in the RIT1 protein. The mutations lead to the production of an altered RIT1 protein that is either continuously turned on (active) or has prolonged activation. The abnormally active protein alters normal RAS/MAPK signaling and leads to abnormal cell proliferation, which disrupts the development of organs and tissues throughout the body.

Cancers

Mutations in the RIT1 gene have been found in several different types of blood cell cancer (leukemia), including acute myeloid leukemia (AML), chronic myelomonocytic leukemia (CMML), and a bone marrow disease called myelodysplastic syndrome (MDS). Similar to the RIT1 gene mutations that cause Noonan syndrome, the mutations involved in these cancers likely result in a constitutively active protein. As a result, cell growth is continuously promoted and cells grow and divide uncontrollably leading to cancer formation. Unlike the Noonan syndrome mutations, the RIT1 gene mutations associated with leukemia are somatic mutations, which means they occur during a person's lifetime and are not inherited.

Other Names for This Gene

  • GTP-binding protein Roc1
  • MGC125864
  • MGC125865
  • Ras-like without CAAX 1
  • ras-like without CAAX protein 1
  • RIBB
  • RIT
  • ROC1

Frequently Asked Questions

RIT1 is part of the RAS/MAPK signaling pathway, which influences cardiac development. Certain RIT1 mutations are strongly associated with hypertrophic cardiomyopathy or pulmonary valve stenosis in Noonan syndrome. The altered protein can cause excessive cell growth in heart muscle or valve tissue, leading to thickened walls or narrowed outflow tracts. Regular cardiac imaging (echocardiogram) is essential to monitor for these complications.
Management is multidisciplinary. Growth hormone therapy may be considered for short stature after endocrinology evaluation. Early intervention services (physical, occupational, speech therapy) address developmental delays. Regular monitoring of thyroid function, bleeding tendencies, and orthopedic problems is recommended. No therapy directly corrects the RIT1 signaling defect, but symptom‑focused treatments improve quality of life.
If you carry a pathogenic RIT1 variant, each pregnancy carries a 50 % risk of transmission. Options include: (1) natural conception with prenatal diagnostic testing (chorionic villus sampling at 10‑12 weeks or amniocentesis at 15‑18 weeks) to determine fetal status; (2) pre‑implantation genetic testing for monogenic disorders (PGT‑M) with IVF, allowing selection of embryos without the mutation; or (3) use of donor gametes or adoption. A genetic counselor can help weigh the medical, ethical, and emotional aspects of each choice.
Yes. RIT1 mutations that cause Noonan syndrome are typically autosomal dominant: a single altered copy is enough to produce the phenotype. If the mutation arose de novo (new in the child), parents are unlikely to carry it, but testing can confirm. If a parent is a carrier, each sibling has a 50 % chance of inheriting the mutation. Testing at‑risk relatives helps guide surveillance for cardiac, growth, and developmental issues.
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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