Deletions

Definition

Deletions refer to the loss of a segment of DNA from a chromosome, which can lead to the absence of one or more genes. This can significantly impact cellular function and contribute to the development of various diseases, including cancer, by disrupting normal gene expression and protein production.

5 Must Know Facts For Your Next Test

1. Deletions can result in frameshift mutations, which change the reading frame of the genetic code and often produce nonfunctional proteins.
2. In cancer, deletions often affect tumor suppressor genes, leading to a loss of regulatory control over cell division.
3. Certain types of cancers, like chronic lymphocytic leukemia (CLL) and breast cancer, are frequently associated with specific chromosomal deletions.
4. Deletions can occur at various scales, from a single nucleotide to large sections of a chromosome.
5. Detection of deletions can be performed using techniques like PCR, FISH, or whole-genome sequencing, helping in cancer diagnosis and treatment planning.

Review Questions

• How do deletions contribute to the development of cancer at a molecular level?
  • Deletions can lead to the loss of crucial tumor suppressor genes that normally inhibit uncontrolled cell growth. When these genes are deleted, cells may lose their ability to regulate division, leading to increased proliferation and tumor formation. Additionally, deletions may create conditions for oncogenes to become activated, further promoting cancer progression.
• Discuss the differences between deletions affecting oncogenes versus tumor suppressor genes in the context of cancer.
  • Deletions affecting oncogenes can result in reduced expression of proteins that promote cell growth and division, potentially leading to slower tumor development. In contrast, deletions of tumor suppressor genes remove critical checkpoints that prevent uncontrolled cell proliferation, often resulting in rapid tumorigenesis. The effects on cellular pathways differ significantly, where oncogene deletions might hinder growth while tumor suppressor deletions remove essential regulation.
• Evaluate the role of genetic testing in identifying deletions associated with specific cancers and how this influences treatment options.
  • Genetic testing plays a vital role in detecting deletions linked to various cancers by identifying genetic abnormalities that may inform prognosis and treatment strategies. For instance, identifying a deletion in the TP53 gene can indicate a poor prognosis and guide more aggressive treatment approaches. Moreover, understanding specific deletions can help tailor targeted therapies that address particular molecular pathways disrupted by these genetic changes, improving patient outcomes significantly.

Related terms

Chromosomal Aberrations: Alterations in the structure or number of chromosomes that can lead to genetic disorders or cancer.

Oncogenes: Genes that have the potential to cause cancer when mutated or expressed at high levels, often affected by deletions.

Tumor Suppressor Genes: Genes that normally help prevent uncontrolled cell growth, which can be inactivated by deletions.