Disrupting a gene (knockout)

Correcting a mutation (repair)

Inserting new DNA (knock-in)

Regulating gene activity without changing sequence (epigenome editing)

Identify gene/variant linked to a trait or disease

Select precise genomic coordinates

Typically a guide component that recognizes the DNA sequence

Determines where the edit occurs and helps limit off-target activity

Methods include viral vectors, lipid nanoparticles, electroporation, microinjection

Many systems create a DNA break or chemical base change

Repair pathways determine the final outcome

Genotyping (PCR, sequencing)

Functional testing (protein levels, phenotype)

Components

Key Idea

Outcomes after cutting

Protein domains engineered to bind specific DNA triplets

Nuclease domain cuts DNA when paired correctly

Often used for targeted knockouts/knock-ins in certain contexts

Modular DNA-binding proteins recognize individual bases

Paired nucleases create targeted cuts

Known for high specificity but larger constructs

Changes single DNA letters without making a double-strand break

Typical conversions

Useful for point mutations

“Search-and-replace” approach using a specialized guide

Can install small insertions, deletions, and all base-to-base substitutions

Often avoids double-strand breaks

Uses targeting systems to recruit activators/repressors

Changes gene expression levels without altering DNA sequence

Quick repair, often introduces small errors

Commonly used for gene knockouts

Uses a DNA template to make precise changes

More efficient in dividing cells; timing and delivery are critical

Influence outcomes in base/prime editing and certain cut-based edits

Cells removed from patient/organism, edited in lab, then returned

Common for blood and immune cells

Editors delivered directly into the body

Requires tissue targeting (e.g., liver, eye, muscle)

Viral

Non-viral

Percentage of cells successfully edited

Unintended edits at similar sequences

Detection via targeted assays and genome-wide methods

Not all cells receive the same edit, especially in embryos

Larger deletions, rearrangements, or unintended insertions

Deep sequencing, functional assays, long-term follow-up in clinical contexts

Sickle cell disease / beta-thalassemia

Cystic fibrosis (research/targeted approaches)

Muscular dystrophies (research)

Retinal genetic diseases

CAR-T and engineered T cells

Tumor resistance and relapse mitigation

HIV (research and early clinical directions)

Editing pathways for repair and regeneration

Potential integration with stem cell therapies and tissue engineering

Knockout/knock-in screens to identify disease genes and drug targets

Validate targets and model diseases in cell lines and organoids

Patient-specific edits in cells to test treatment responses

One-time or durable treatments

Targeted intervention at the genetic root cause

Efficient, tissue-specific delivery

Immune responses to editor components

Long-term safety and monitoring

Somatic editing vs germline editing

Informed consent, access, equity, and governance

Disable genes that make plants susceptible to pathogens

Remove traits that reduce yield under stress

Mimic beneficial natural variants found in related varieties

Adjust expression levels to optimize growth, flowering time, or metabolism

Edit multiple genes simultaneously for complex traits

Reduce susceptibility genes

Enhance innate immune responses

Modify plant defense pathways or volatile compounds

Drought/heat/salt tolerance via water-use efficiency and stress signaling

Oil composition, starch properties, micronutrient levels

Reduced allergens or anti-nutritional factors (where feasible)

Slower browning, improved texture, longer storage

Reduce vulnerability to certain infections

Growth efficiency, heat tolerance, hornless cattle (polled trait)

Milk composition, meat characteristics (context-dependent and regulated)

Faster and more precise than traditional breeding for specific targets

Can reduce chemical pesticide use and losses

Trait complexity (many traits are polygenic)

Off-target edits and unintended effects require testing

Acceptance, labeling, and regulatory variation by region

Edits in body cells; not inherited by offspring

Edits in embryos/egg/sperm; heritable

Highly restricted or banned in many jurisdictions

Trials, regulatory review, post-treatment monitoring

Field trials, environmental assessment, commercialization decisions