The CRISPR gene editing system is a major technical advance. It does open up the near term possibility of making a few small changes to a human embryo’s DNA, but I don’t find that particularly interesting or alarming.
What makes CRISPR better than previous tech for gene modification is that it works at high efficiency–1% to 60% with very high specificity. I read a recent paper testing CRISPR on human embryos that reported 50% effectiveness. Given a handful of embryos to work with, there is a very good chance of making a single change in one embryo.
We have very little knowledge or technology for making positive changes to animals which is a huge limitation to genetic ‘engineering’. Mostly what is understood are disease causing (or predisposing) genetic variants. So a single change (maybe in a few years, a handful of changes?) can be made to a human embryo. There are other limits to modifying human embryos apart from lack of knowledge. The more time an embryo or human embryonic stem cell is cultured, the more it is manipulated, the greater the chance of something going wrong, and the child being born with problems. This tech is great for manipulating animals in the lab. If many or most of them have the genetic change, great! If some are born with defects, cull them, or breed another generation and use those in experiments (often the first generation has non-genetic defects that breed away). But these are huge problems if you are working on humans, because things that increase the risk of getting a damaged child are not desirable.
Long term (100-1000 years), when increases in understanding of biology make improvements (or significant changes of any sort) in humans possible, I think what we’ll see is that the people with the least concern for child welfare will be the most willing to experiment on them.
The really exciting possibilities CRISPR opens up is in genetic treatment of human disease in the tissues of kids and adults. There is delivery tech (well tested viral vectors, and a host of other methods) that can get CRISPR into a good percentage of cells (10% to 50+%) in many tissues, and once there, CRISPR will edit a good fraction of those cells. For many diseases, fixing a genetic defect in 1%, 10% or 20% of cells is enough to treat the disease, so genetic treatment of host of diseases is now possible. Things like hemophilia, some muscular dystrophy, maybe Huntington’s Disease, metabolic diseases, Parkinson’s disease, and on and on. There will be a lot of exciting advances turning that ‘possible’ into actual treatments for different diseases over the next decade or two.
The other major effect of CRISPR tech is that it makes animal experimentation faster and cheaper, and will accelerate basic biological research. We still don’t know what the majority of indivdual genes do, let alone how they work in complexes and networks in cells.