Designing a gene editing clinical trial requires a thoughtful approach towards the accidental editing of sperm and egg cells.

The consensus opinion among scientists and regulators … is that we are comfortable delivering edits to adult cells, but we are not yet ready to deliver gene edits into germ cells.

Germ cells include sperm, eggs or embryos. DNA edits delivered into germ cells may be passed on to children and, in doing so, may alter the downstream human lineage.

In contrast, DNA edits delivered to adult cells, like bone marrow stem cells, is called somatic cell editing. Somatic cell edits will only alter the treated individual and are much less controversial than germline editing.

Here’s the conundrum . . . we may see accidental germline editing as we deliver gene editing medicine into adult cells in the human body. This is not an issue with ex vivo gene editing (i.e. Casgevy) but it is a concern with in vivo gene editing. When I say in vivo gene editing, I mean genetic medicine delivered directly into the bloodstream.

So far, there is no clinical trial evidence that accidental germline edits are happening.

But, there is evidence that accidental germline edits are a possibility.

I delve into this topic in the video below…