Last week, a Chinese group from Sun Yat-sen University, reported that they had created the first genetically-modified human embryo. It was reported that they had taken “human tripronuclear embryos”, and altered mutant DNA that causes the human disease β-thalassemia.

β-thalassemia is a life-threatening disease that affects 100,000 people worldwide.

Although there has much controversy (ethical and safety concerns) surrounding the subject, this new technology also hold a lot of promise.

The technology has the potential to cure diseases like:

• ▪ cystic fibrosis
• ▪ Huntington’s
• ▪ Or remove the BRCA mutation (reducing risk of breast and ovarian cancer)

What did the Chinese researchers do and why is it causing controversy in the scientific community? 

The experiments were performed on human embryos and collected non-viable embryos from IVF clinics. Scientists used non-viability argument as the ethical justification. Embryos were not capable of resulting in a human life, because they were tripronuclear.

Tripronuclear: One egg that has been fertilized by two sperm

This cannot result a live baby. These embryos were injected with CRISPR/CAS system (molecular scissors that can cut and paste genes). But it provides the ability to target a specific segment of DNA. Researchers targeted the HBB gene which causes β-thalassemia. They cut out the disease-causing region and replaced it. This of cutting and pasting on a word doc, but in your DNA

Researchers reported “off target effects” and “mosaicism” – Meaning: editing sometimes occurred atthe wrong place in the DNA. This did not occur in all embryos equally. There were many mistakes, which were not anticipated.

The Controversy

1. Ethical issue surrounding the use of human embryos for scientific research
   1. Concerns around creating designer babies
   2. Editing went so wrong in so many embryos, not as precise as expected
2. Without total control of the DNA editing process, the outcome for a baby that is “edited” is completely unknown
   1. Right now, technology is unpredictable and uncertain
   2. Possibility of eliminating certain diseases by gene editing is probably not in the near future
   3. Also need to figure out how to test if this technology is even safe to use in a live embryo
   4. Clearly testing on a live human baby is problematic
   5. Consensus among scientific community:
   6. Research must proceed with extreme caution.