What is gene therapy?

Exploring the advancing science behind
gene therapy

Gene therapy is an innovative approach to treatment for a medical condition by introducing a new fully functioning, or working, gene into the body, or by turning off or changing the gene that is causing the condition.

Patient receiving gene therapy

For people with hemophilia B, gene therapy has the potential to sustain blood-clotting ability by addressing the cause of the condition: a faulty F9 gene.

For hemophilia B, the functional, or working, gene is designed with instructions to create the correct protein that makes factor IX (FIX). The working gene is delivered to the liver by an AAV vector.

Patient receiving gene therapy

For people with hemophilia B, gene therapy has the potential to sustain blood-clotting ability by addressing the cause of the condition: a faulty F9 gene.

For hemophilia B, the functional, or working, gene is designed with instructions to create the correct protein that makes factor IX (FIX). The working gene is delivered to the liver by an AAV vector.

What is AAV gene therapy?

Gene therapies work through a variety of approaches including functional gene transfer. Approaches for inherited conditions stemming from a single genetic mutation, including hemophilia B, have predominantly focused on the delivery of a functional gene using a viral vector.

AAV vector

Most gene therapies for hemophilia B currently in clinical trials use a certain type of vector called an adeno-associated virus, or AAV.

AAV vector
Scientific laboratory

AAV gene therapy is built on trusted scientific advances

  • Built on decades of proven clinical research—the first patients received gene therapy in 1970

  • More than 250 AAV-based clinical trials currently underway across a variety of conditions

  • 2 FDA/EMA* approvals for gene therapies (treating hereditary retinal dystrophy and spinal muscular atrophy)

*FDA=Food and Drug Administration, EMA=European Medicines Agency.

Why is AAV gene therapy a
promising option for hemophilia B?

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