Gene Editing vs. Gene Therapy: What's the Difference?

The Quick Answer

Gene therapy adds a new, working copy of a gene to your cells to compensate for one that isn't working properly. The original faulty gene remains untouched.

Gene editing changes your existing genes directly — correcting, disabling, or modifying them at the DNA level. It fixes the problem at its source.

Side-by-Side Comparison

How Gene Therapy Works

Gene therapy typically uses a modified virus (called a vector) to deliver a healthy copy of a gene into a patient's cells. The virus has been engineered so it can't cause disease — it's just a delivery vehicle.

Once inside the cell, the new gene produces the protein that the faulty gene couldn't. The original broken gene is still there, but the new one compensates for it.

Strengths of Gene Therapy

• Longer track record with more approved treatments
• Doesn't require cutting DNA, so no risk of off-target edits
• Effective for conditions where simply adding a working gene is enough

Limitations of Gene Therapy

• The added gene may not integrate in the ideal location
• Effects may diminish over time, requiring retreatment
• Viral vectors can trigger immune responses
• Doesn't work well for conditions requiring a gene to be turned off

How Gene Editing Works

Gene editing uses molecular tools (most commonly CRISPR-Cas9) to locate a specific spot in your DNA and make a precise change. This might mean correcting a mutation, disabling a harmful gene, or inserting a corrective sequence.

Because it changes the gene itself, the repair is typically permanent and addresses the root cause of the condition.

Strengths of Gene Editing

• Highly precise — targets exact DNA locations
• Fixes the root cause rather than compensating for it
• Can disable genes (useful for conditions caused by overactive genes)
• Rapidly improving with newer tools like base and prime editors

Limitations of Gene Editing

• Newer technology with less long-term data
• Risk of off-target changes (though this is decreasing)
• Delivering editing tools to the right cells is still challenging
• Permanent changes mean mistakes are harder to reverse

Which Is Better?

Neither approach is universally better. The right choice depends on the specific condition, the genes involved, and the treatment goals.

Some conditions are better suited to gene therapy (where adding a gene is sufficient), while others benefit from gene editing (where the existing gene needs to be corrected or disabled). In many cases, researchers are developing both approaches in parallel.

Increasingly, the line between the two is blurring. Many modern therapies combine elements of both — using gene editing tools delivered by gene therapy vectors, for example.

Approved Therapies

Approved Gene Therapies (examples)

• Zolgensma — Spinal muscular atrophy (SMA)
• Luxturna — Inherited retinal dystrophy
• Hemgenix — Hemophilia B
• Skysona — Cerebral adrenoleukodystrophy

Approved Gene Editing Therapies (examples)

• Casgevy — Sickle cell disease and beta-thalassemia (CRISPR-based)

The number of approved gene editing therapies is expected to grow significantly as more clinical trials complete.

The Bottom Line

Gene therapy and gene editing are complementary approaches to treating genetic diseases. Gene therapy has a longer track record, while gene editing offers greater precision and the potential to fix problems at their source. Both are advancing rapidly, and both represent major breakthroughs for patients who previously had limited options.

The best way to understand which approach may be relevant to your situation is to stay informed and explore the specific research related to your condition.