Deletion

Definition

A deletion is a type of genetic mutation where a segment of DNA is removed or lost from the chromosome. This alteration can impact gene function, leading to various effects on an organism's phenotype, and plays a significant role in copy number variations, as it results in a reduction of genomic material which can affect gene dosage and expression levels.

5 Must Know Facts For Your Next Test

1. Deletions can vary in size from a single nucleotide to large segments of chromosomes and can lead to significant phenotypic changes.
2. In terms of evolutionary biology, deletions can contribute to genetic diversity and adaptation by altering gene functions.
3. Deletions are often detected using genomic technologies like array comparative genomic hybridization (aCGH) or next-generation sequencing.
4. Some deletions are benign and have no observable effect, while others can be linked to genetic disorders such as cystic fibrosis or certain cancers.
5. The impact of a deletion can depend on its location within the genome, particularly if it affects critical genes or regulatory elements.

Review Questions

• How do deletions contribute to genetic diversity within populations?
  • Deletions contribute to genetic diversity by introducing variations in gene content among individuals. By removing specific segments of DNA, deletions can alter gene function or expression levels, which may confer adaptive advantages or disadvantages depending on environmental conditions. This process can lead to new traits that may be beneficial for survival and reproduction, thus playing a crucial role in natural selection and evolution.
• Discuss the methods used to detect deletions in genomic studies and their importance in understanding copy number variations.
  • Detection methods for deletions include techniques like array comparative genomic hybridization (aCGH) and next-generation sequencing (NGS), both of which allow for high-resolution analysis of genomic alterations. These methods are crucial for understanding copy number variations because they can identify not only deletions but also duplications and other structural variations. By analyzing these changes, researchers can gain insights into their associations with diseases and how they contribute to phenotypic diversity.
• Evaluate the implications of deletions on gene dosage and expression levels in relation to genetic disorders.
  • Deletions significantly affect gene dosage and expression levels, particularly when they involve genes that are haploinsufficient—meaning that one functional copy is not enough for normal function. This reduced gene dosage can lead to genetic disorders by diminishing the production of essential proteins or disrupting regulatory networks. For instance, in conditions like Duchenne muscular dystrophy, specific deletions within the dystrophin gene result in a loss of protein function, leading to severe muscle degeneration. Understanding these implications helps in developing targeted therapies and interventions for genetic disorders.

Related terms

Duplication: A genetic mutation where a segment of DNA is copied, resulting in an increase in the number of copies of a particular gene or region.

Insertions: A type of mutation where one or more nucleotide bases are added into a DNA sequence, potentially disrupting normal gene function.

Copy Number Variation (CNV): A form of structural variation where sections of the genome are duplicated or deleted, leading to differences in the number of copies of a particular gene between individuals.