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Gene therapy on brink of golden age: Here’s why 

Gene therapy can cure some forms of hemophilia. Meet someone who has already undergone the procedure and is now cured of hemophilia B.

Bruce is 18 years old and for most of his life he has had to be extremely careful. During childhood, and all through high school, sports were out of the question because he has hemophilia B, a bleeding disorder, also called “Christmas disease” since it results from a deficiency of coagulation factor IX. Coagulation factor IX is also known as the “Christmas factor” and, because of a faulty gene on the X-chromosome that he received from his mother, it was useless in Bruce. Bruce’s mother is perfectly normal. In fact, all the females in Bruce’s family are normal; a classic feature of an X-linked recessive disease.

Until recently, Bruce had to receive recombinant factor IX –the protein his body doesn’t make can be synthesized by genetically modified microorganisms– through intravenous infusion several times per week. That kept Bruce from bleeding to death but he still suffered from frequent “breakthrough bleeds” because the infused factor did not render him completely normal. Had he skinned a knee, as so many school children routinely do during recess, he could have bled into the joint. Had he bumped his head, even modestly, blood could have accumulated in the connective tissue layers between his skull and brain, causing a life-threatening situation. That’s why he avoided sports, all sports, and had to be cautious in everything he did, even shaving.

But last year, Bruce got the best Christmas present ever: a permanent cure of his Christmas disease. Now, he can play soccer and basketball with the kids at the after school program where he volunteers as a big brother. He no longer needs intravenous infusions of factor IX and if he nicks himself shaving, there will be no concern; he’ll heal as quickly as anyone else, since his liver now makes working factor IX. This all happened because of gene therapy and Bruce is quite satisfied, even though he will have to be monitored for the rest of his life (just in case the gene therapy produces any long-term effects). Unlike hemophilia A, the most common type of hemophilia, where gene therapy faces slightly more difficult technical challenges, clinical trials to replace the needed gene, leading to permanent cure for hemophilia B, are well underway.

Hemophilia A will follow soon, and in the meantime gene therapy is also being tested in human patients to treat a class of conditions known as hemoglobinopathies (where red blood cells make either defective globin proteins, or not enough of them) and for certain eye diseases that lead to blindness due to inherited gene defects involving the retina.

Read Full Article: Gene therapy on brink of golden age: Here’s why | Genetic Literacy Project

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