Copy Number Variations (CNVs)

Definition

Copy Number Variations (CNVs) are a type of structural variation in the genome where sections of DNA are repeated, resulting in a variable number of copies of that particular region. CNVs can influence gene dosage, affect gene expression, and contribute to phenotypic diversity, making them particularly significant in the study of rare diseases and genetic disorders.

5 Must Know Facts For Your Next Test

1. CNVs can range in size from a few hundred base pairs to several megabases and can encompass one or multiple genes.
2. These variations can be inherited from parents or arise de novo, contributing to the genetic landscape associated with rare diseases.
3. CNVs have been implicated in various conditions, including autism spectrum disorders, schizophrenia, and developmental delays.
4. Detection of CNVs typically involves techniques such as array comparative genomic hybridization (aCGH) and next-generation sequencing (NGS).
5. Understanding CNVs is essential for variant interpretation as they may influence clinical outcomes and treatment responses in individuals with rare genetic disorders.

Review Questions

• How do copy number variations (CNVs) influence gene expression and contribute to rare diseases?
  • CNVs can alter gene dosage by changing the number of copies of a gene present in an individual's genome. This variation can lead to either overexpression or underexpression of genes, affecting biological pathways and ultimately contributing to phenotypic traits associated with rare diseases. For example, increased gene dosage from a duplication may enhance pathogenic processes, while loss of function due to deletions may disrupt normal cellular functions.
• Discuss the methodologies used to identify copy number variations and their significance in the context of genomic medicine.
  • Techniques such as array comparative genomic hybridization (aCGH) and next-generation sequencing (NGS) are commonly employed to detect CNVs. These methodologies allow for comprehensive genomic analysis, enabling clinicians to identify pathogenic variants associated with rare diseases. The significance lies in their ability to provide crucial information for diagnosis, prognosis, and potential targeted therapies based on the presence of specific CNVs.
• Evaluate the implications of copy number variations on personalized medicine and how they may affect treatment decisions for patients with rare diseases.
  • Copy number variations can significantly impact personalized medicine by influencing how individual patients respond to specific treatments. Understanding a patient's CNV profile helps clinicians tailor therapies based on the genetic underpinnings of their condition. For instance, patients with certain CNVs may benefit from targeted therapies that address the underlying genetic alterations, thus enhancing treatment efficacy and reducing adverse effects. Additionally, knowing CNV involvement in a patient's rare disease can guide monitoring strategies and inform genetic counseling for families.

Related terms

Structural Variants: Large-scale alterations in the genome, including deletions, duplications, inversions, and translocations that can impact gene function.

Single Nucleotide Polymorphisms (SNPs): The most common type of genetic variation among people, where a single nucleotide differs between individuals, potentially influencing traits and disease susceptibility.

Genomic Imbalance: An uneven distribution of genetic material resulting from CNVs or other structural variations, which can lead to disruptions in normal cellular functions.