Children (and adults) with hemophilia are slow to form blood clots, so are at constant risk for uncontrolled bleeding. Even when the skin isn’t broken, a fall or a simple toe stub can become a serious medical issue: internal bleeding cause permanent damage to muscles and joints. While regularly replacing the missing or malfunctioning clotting factor can keep hemophilia under control, the protein must be infused multiple times per week — for life.
In the case of hemophilia A, the most common form, patients must receive infusions of factor VIII, every other day in severe cases. But what if, instead, they could make factor VIII on their own? For decades, scientists have tried to do this with gene therapy, but have come up against barriers.
“The gene for factor VIII is enormous,” says Juan Melero-Martin, PhD, a researcher in Boston Children’s Hospital’s Department of Cardiac Surgery. “You can try to deliver it with a virus, but either the gene doesn’t fit into the virus, or the virus can carry it but cannot insert the gene permanently into the genome. Some people have tried truncating the gene.”
