While gene therapy is the most widely used genetic medicine to treat genetic disorders, there are still many limitations.
Gene therapy is largely divided between ex vivo and in vivo approaches. Ex vivo therapies, like CAR-T cell therapies, use retroviral vectors to deliver corrective DNA directly to cells outside of the body. In vivo therapies use adeno-associated virus (AAV) vectors to deliver episomal DNA—DNA that is maintained separately from the rest of our genome—into cells inside of the body.
Gene therapy can treat recessive genetic mutations but cannot directly treat dominant-negative mutations. When deployed in vivo, most gene therapies do not integrate into the genome, compromising long-term gene expression in dividing cells.