Editing Human Embryos: So This Happened

Carl Zimmer in his excellent blog, The Loom:

Earlier this week, Chinese researchers reported that they edited the genes of human embryos using a new technique called CRISPR. While these embryos will not be growing up into genetically modified people, I suspect this week will go down as a pivotal moment in the history of medicine. David Cyranoski and Sara Reardon broke the news today at Nature News. Here I’ve put together a quick guide to the history behind this research, what the Chinese scientists did, and what it may signify.

There are thousands of genetic disorders that can occur if a mutation happens to strike an important piece of DNA. Hemophilia, sickle cell anemia, cystic fibrosis– the list goes on and on. As I wrote in the Atlantic in 2013, a particularly cruel genetic disorder, fibrodysplasia ossificans progressiva causes people to grow a second skeleton. It’s caused by a mutation that changes a single “letter” of a single gene, called ACVR1. The protein encoded by the gene doesn’t work properly, triggering a wave of changes in people’s bodies, with the result that when they heal from a bruise, they replace entire chunks of muscle with new bone.

In some cases, people can offset many of the symptoms of genetic disorders with simple changes, like watching what they eat. In other cases, like hemophilia, they have to take regular doses of drugs to remain healthy. In other cases, like fibrodysplasia ossificans progressiva, there’s no effective treatment yet.

For decades, scientists have tried to develop a new way to treat genetic disorders like these: to heal the patient, heal the gene.

More here.