Accident & Desire: Inadvertent Germline Effects in Clinical Research

Gene therapy is still a very crude way of treating very complicated problems. It's hard to get new genes to go where they're needed, and hard to keep them from going where they're not wanted. The worst‐case scenario is that they find their way into a patient's germ cells—eggs or sperm—and end up harming the patient's offspring. Yet this possibility is hard to study in human trials, and would be hard to deal with in the clinic. It should, instead, simply be avoided. Doing so requires fundamentally changing our approach to gene therapy.