38.10
The Retinoblastoma Gene
Rb gene was the first-ever tumor suppressor gene discovered. Loss of function mutations in the Rb gene leads to retinoblastoma - cancer of the retinal cells of the eye.
A healthy individual possesses two functional copies of the Rb gene, which encode a retinoblastoma protein that regulates cell cycle progression.
In the case of hereditary retinoblastoma, a child inherits one functional and one mutated Rb gene from their parents. Every somatic cell of these individuals will therefore have only one normal Rb gene, but the amount of Rb protein produced is enough to maintain the normal cell cycle.
However, if any of these somatic cells lose the other functional copy of the gene, the cell stops producing the Rb protein altogether and becomes cancerous.
In rare cases, even when an individual inherits two functional Rb gene copies, both copies of the Rb gene can be lost or inactivated in a single cell lineage by two independent events over time.
Such double loss of function mutations in the retinal cells leads to non-hereditary or sporadic retinoblastoma.
Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However, when a somatic cell loses the second copy of the gene as well, it triggers the development of tumors. Such individuals develop multiple tumors in both eyes. In the disease's nonhereditary form, a cell undergoes two independent somatic mutations and loses both functional copies of the Rb gene. Such cells become cancerous and lead to the development of a tumor in only one eye.
Retinoblastoma is one of the most common intraocular malignant tumors in children, with an incidence rate of 1 in 15,000 to 1 in 18,000. While the hereditary form comprises 25-35% of the total retinoblastoma cases, the nonhereditary or sporadic form comprises 65-75% of the cases.
Rb gene was the first-ever tumor suppressor gene discovered. Loss of function mutations in the Rb gene leads to retinoblastoma - cancer of the retinal cells of the eye.
A healthy individual possesses two functional copies of the Rb gene, which encode a retinoblastoma protein that regulates cell cycle progression.
In the case of hereditary retinoblastoma, a child inherits one functional and one mutated Rb gene from their parents. Every somatic cell of these individuals will therefore have only one normal Rb gene, but the amount of Rb protein produced is enough to maintain the normal cell cycle.
However, if any of these somatic cells lose the other functional copy of the gene, the cell stops producing the Rb protein altogether and becomes cancerous.
In rare cases, even when an individual inherits two functional Rb gene copies, both copies of the Rb gene can be lost or inactivated in a single cell lineage by two independent events over time.
Such double loss of function mutations in the retinal cells leads to non-hereditary or sporadic retinoblastoma.
- Retinoblastoma (RB) - A type of cancer that initiates in the retina caused by mutated rb gene.
- RB Gene - The gene that when mutated, leads to Retinoblastoma.
- RB Tumor Suppressor - The RB gene's function as a tumor suppressor before mutation.
- RB Cell Cycle - The role RB gene plays in cell growth and division cycle.
- Hereditary Retinoblastoma - A form of RB that is passed down from parents to their child.
- Define RB Gene – The gene responsible for retinoblastoma when mutated (e.g., RB gene).
- Contrast Normal RB vs Mutated RB – Identify the differences between normal and mutated RB gene (e.g., functionality).
- Explore Retinoblastoma – Understand how this disease manifests and progresses (e.g., cell growth).
- Explain RB and Cell Cycle – Understand how RB gene affects cell growth and division.
- Discuss Hereditary Retinoblastoma – Provide an understanding of how RB can be inherited.
- What is Retinoblastoma and how does the RB gene link to it?
- What is the difference between normal and mutated RB gene function?
- How exactly does Retinoblastoma develop and progress in the body?
From Chapter 38:
Now Playing
38.10 : The Retinoblastoma Gene
Cancer
2.3K Views
38.1 : What is Cancer?
Cancer
7.0K Views
38.2 : Cancers Originate from Somatic Mutations in a Single Cell
Cancer
3.9K Views
38.3 : Tumor Progression
Cancer
3.5K Views
38.4 : Adaptive Mechanisms in Cancer Cells
Cancer
4.2K Views
38.5 : The Tumor Microenvironment
Cancer
2.9K Views
38.6 : Metastasis
Cancer
3.6K Views
38.7 : Cancer-Critical Genes I: Proto-oncogenes
Cancer
6.5K Views
38.8 : Cancer-Critical Genes II: Tumor Suppressor Genes
Cancer
3.0K Views
38.9 : Loss of Tumor Suppressor Gene Functions
Cancer
2.0K Views
38.11 : Mechanisms of Retrovirus-induced Cancers
Cancer
3.0K Views
38.12 : Rous Sarcoma Virus (RSV) and Cancer
Cancer
5.3K Views
38.13 : The Ras Gene
Cancer
2.7K Views
38.14 : mTOR Signaling and Cancer Progression
Cancer
1.6K Views
38.15 : Cancer Stem Cells and Tumor Maintenance
Cancer
2.1K Views
See More