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What is investigational gene therapy?

The purpose of this site is to provide information to patients and caregivers about the field of gene therapy and how it is being investigated for use in haemophilia.

Introduction to gene therapy research

Gene therapy is a potential approach to treating or preventing genetic diseases. The goal of gene therapy is to address a genetic disease at its source – the gene. This can be done by modifying (changing) genes or creating new functional genes in a laboratory and delivering them to specific cells in the body.


50 years of researchScientists have been investigating gene therapy for more than 50 years, and the science around gene therapy continues to evolve. To date, more than 2,600 gene therapy clinical trials are planned, ongoing, or have been completed for different genetic diseases.


Gene therapy is the approach being most broadly investigated for use in haemophilia. This approach introduces a new functional copy of a gene with the aim of restoring or enhancing its original function. It is sometimes referred to as gene augmentation, gene transfer, or gene replacement. One approach being researched is adeno-associated virus (AAV) vector gene therapy.


AAV gene therapy
Creating new functional genes in a laboratory and delivering them to specific cells in the body


Vector carrying new functional gene into target cell




Aim of gene therapy research in haemophilia

Why have scientists continued to research gene therapy for so long? Their efforts are aimed at finding a potential one-time or infrequent treatment as an additional treatment option to replace ongoing, recurring treatments for haemophilia. The hope is to move from the highs and lows in clotting factor levels (often called “peaks and troughs”) to a continuously expressed factor level.



Current therapy for haemophilia

A graph of current therapy for haemophilia showing factor levels with peaks and troughs

Aim: continuously expressed factor level

A graph of the aim of gene therapy showing the potential of continuously expressed factor level

Other techniques being investigated to treat or prevent disease at the gene level

Scientists are studying other approaches for treating or preventing genetic disease at its source – the gene.


Gene editing, sometimes called genome editing or genomic editing, modifies existing genes in a person’s DNA to correct specific mutations. Some examples of investigational gene editing technologies include CRISPR and Zinc Finger Nucleases.


Chromosome with gene containing a mutation Target DNA/gene Gene editing guide RNA and DNA-cutting enzyme Edited DNA

Cell therapy transplants whole cells capable of adding a new or desired function into a person. The genes in the cells may or may not be modified by gene therapy or gene editing while outside the body before being returned to the patient.


Cells modified by cell therapy