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 three other genes: 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
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, rather than promptly switching on and off in response to other cellular proteins. 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, resulting in the signs and symptoms of Noonan syndrome.More About This Health Condition
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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 (described above), 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
- Ras-like without CAAX 1
- ras-like without CAAX protein 1
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
- Berger AH, Imielinski M, Duke F, Wala J, Kaplan N, Shi GX, Andres DA, Meyerson M. Oncogenic RIT1 mutations in lung adenocarcinoma. Oncogene. 2014 Aug 28;33(35):4418-23. doi: 10.1038/onc.2013.581. Epub 2014 Jan 27. Citation on PubMed or Free article on PubMed Central
- Gómez-Seguí I, Makishima H, Jerez A, Yoshida K, Przychodzen B, Miyano S, Shiraishi Y, Husseinzadeh HD, Guinta K, Clemente M, Hosono N, McDevitt MA, Moliterno AR, Sekeres MA, Ogawa S, Maciejewski JP. Novel recurrent mutations in the RAS-like GTP-binding gene RIT1 in myeloid malignancies. Leukemia. 2013 Sep;27(9):1943-6. doi: 10.1038/leu.2013.179. Epub 2013 Jun 14. Citation on PubMed
- Kouz K, Lissewski C, Spranger S, Mitter D, Riess A, Lopez-Gonzalez V, Lüttgen S, Aydin H, von Deimling F, Evers C, Hahn A, Hempel M, Issa U, Kahlert AK, Lieb A, Villavicencio-Lorini P, Ballesta-Martinez MJ, Nampoothiri S, Ovens-Raeder A, Puchmajerová A, Satanovskij R, Seidel H, Unkelbach S, Zabel B, Kutsche K, Zenker M. Genotype and phenotype in patients with Noonan syndrome and a RIT1 mutation. Genet Med. 2016 Dec;18(12):1226-1234. doi: 10.1038/gim.2016.32. Epub 2016 Apr 21. Citation on PubMed
- Milosavljević D, Overwater E, Tamminga S, de Boer K, Elting MW, van Hoorn ME, Rinne T, Houweling AC. Two cases of RIT1 associated Noonan syndrome: Further delineation of the clinical phenotype and review of the literature. Am J Med Genet A. 2016 Jul;170(7):1874-80. doi: 10.1002/ajmg.a.37657. Epub 2016 Apr 25. Citation on PubMed
- Shi GX, Jin L, Andres DA. A rit GTPase-p38 mitogen-activated protein kinase survival pathway confers resistance to cellular stress. Mol Cell Biol. 2011 May;31(10):1938-48. doi: 10.1128/MCB.01380-10. Epub 2011 Mar 28. Citation on PubMed or Free article on PubMed Central
- Yaoita M, Niihori T, Mizuno S, Okamoto N, Hayashi S, Watanabe A, Yokozawa M, Suzumura H, Nakahara A, Nakano Y, Hokosaki T, Ohmori A, Sawada H, Migita O, Mima A, Lapunzina P, Santos-Simarro F, García-Miñaúr S, Ogata T, Kawame H, Kurosawa K, Ohashi H, Inoue S, Matsubara Y, Kure S, Aoki Y. Spectrum of mutations and genotype-phenotype analysis in Noonan syndrome patients with RIT1 mutations. Hum Genet. 2016 Feb;135(2):209-22. doi: 10.1007/s00439-015-1627-5. Epub 2015 Dec 29. Citation on PubMed