Gene editing and genetic medicine

What are gene editing and genetic medicine?

Gene editing is the process of making targeted, precise changes to DNA in cells. In the lab, researchers use gene editing to study the function of genes by, for example, editing a gene to see the effects of turning it off in cells. 

Gene editing also offers new paths to treating genetic disorders previously considered incurable. There are many genetic diseases caused by single DNA mutations that could potentially be repaired by gene editing technologies. 

Genetic medicines include gene-editing treatments, antisense oligonucleotides (ASOs), and siRNAs, and promise to treat, even cure, rare genetic diseases. Gene editors are designed to edit a specific location in DNA to correct a disease-causing mutation, and ASOs and siRNAs target certain mRNAs involved in disease. 

How does gene editing work? 

There are three different approaches to gene editing being developed as genetic medicines: 

• CRISPR-Cas9: a system that cuts DNA at a specific location in the genome to inactivate a gene, such as a disease-causing gene. This technology is the basis for Casgevy, a treatment for sickle cell disease and the first ever FDA-approved CRISPR gene editing medicine (approved in 2023). CRISPR is also commonly used in the lab as a research tool to study gene function. 
• Base editing: a method that converts one DNA “letter” or base pair to a different base pair. It’s designed to correct specific single-letter mutations that cause rare diseases. 
• Prime editing: a more versatile approach that can make a greater variety of DNA edits, such as inserting, deleting, or replacing larger sections of DNA, to potentially treat or even cure a broad range of genetic diseases. 

Base and prime editing can correct the majority of known disease-causing genetic mutations, and are being tested in at least 25 clinical trials to treat or cure leukemias, rare genetic diseases, and high cholesterol.

How do gene editors reach target cells in the body?

Gene editors need efficient, safe delivery methods to ensure they reach the correct cells and tissues in the body. Delivery technologies package and ferry gene editors into specific cells. They include modified adeno-associated viruses (AAVs), which don’t cause infection and are designed to deliver their cargo to specific cell types. Non-viral delivery technologies include lipid nanoparticles and engineered virus-like particles. 

How are Broad Institute researchers advancing gene editing and delivery?

Broad scientists are pioneers in discovering and developing the three gene editing approaches described above, as well as in creating better AAV technologies for targeted gene editor delivery. They are continuing to advance genetic medicine and delivery methods with the ultimate goal of benefiting patients. 

For example, the Center for Therapeutic Genetics (CTG), a collaborative effort between Broad Institute, Boston Children’s Hospital, and The Jackson Laboratory, was established in 2026 to develop genetic medicines and treat patients for rare disease not as one-off breakthroughs, but as a repeatable practice.