gene therapy

Gene therapy treats disease by changing the genetic instructions inside a patient's cells, rather than by giving a drug that the body will soon clear. If a disease is caused by a broken or missing gene, the idea is to deliver a working copy, or to fix the faulty one, so the cell can make the right protein for itself, potentially for a long time.

Most gene therapies work by packaging the therapeutic DNA inside a delivery vehicle, usually a harmless engineered virus such as an adeno-associated virus, which ferries the genetic cargo into target cells. The cell then reads the added gene and produces the missing protein. Newer approaches edit the genome directly, using tools such as CRISPR to correct a mutation in place.

The promise is a durable, sometimes one-time cure for inherited diseases that previously had no treatment. The challenges are formidable: delivering the gene to the right tissue, avoiding immune reactions to the viral carrier, the risk of disrupting other genes, and very high cost. Effects can also be permanent, which makes safety especially critical.