Gene targeting and gene editing are both techniques for removing or modifying a particular gene, each of which can produce the same ultimate goal. What is the main technical difference in how DNA is modified that differs between these approaches?

Key Concepts

Gene Targeting

Gene targeting is a technique that involves the precise modification of a specific gene within the genome. This is typically achieved through homologous recombination, where a piece of DNA with a desired alteration is introduced into a cell, and the cell's natural repair mechanisms incorporate this change into the target gene. This method is often used in creating knockout models in research.

Gene Editing

Gene editing refers to a broader set of techniques, including CRISPR-Cas9, that allow for the direct alteration of DNA sequences at specific locations in the genome. Unlike gene targeting, which relies on homologous recombination, gene editing can create double-strand breaks in DNA, which the cell then repairs, often leading to insertions or deletions at the target site. This method is faster and more versatile for making precise changes.

Homologous Recombination vs. Non-Homologous End Joining

Homologous recombination is a repair mechanism that uses a homologous sequence as a template for accurate DNA repair, while non-homologous end joining (NHEJ) is a quicker, error-prone process that directly ligates broken DNA ends without a template. Gene targeting primarily utilizes homologous recombination for precise modifications, whereas gene editing techniques like CRISPR often exploit NHEJ to introduce mutations or alterations at the target site.