Human embryos edited to stop disease
Scientists have, for the first time, successfully freed embryos of a piece of faulty DNA that causes deadly heart disease to run in families.
It potentially opens the door to preventing 10,000 disorders that are passed down the generations.
The US and South Korean team allowed the embryos to develop for five days before stopping the experiment.
The study hints at the future of medicine, but also provokes deep questions about what is morally right.
Science is going through a golden age in editing DNA thanks to a new technology called Crispr, named breakthrough of the year in just 2015.
Its applications in medicine are vast and include the idea of wiping out genetic faults that cause diseases from cystic fibrosis to breast cancer.
US teams at Oregon Health and Science University and the Salk Institute along with the Institute for Basic Science in South Korea focused on hypertrophic cardiomyopathy.
The disorder is common, affecting one in every 500 people, and can lead to the heart suddenly stopping beating.
It is caused by an error in a single gene (an instruction in the DNA), and anyone carrying it has a 50-50 chance of passing it on to their children.
In the study, described in the journal Nature, the genetic repair happened during conception.
Sperm from a man with hypertrophic cardiomyopathy was injected into healthy donated eggs alongside Crispr technology to correct the defect.
It did not work all the time, but 72% of embryos were free from diseasecausing mutations.
Dr Shoukhrat Mitalipov, a key figure in the research team, said: “Every generation on would carry this repair because we’ve removed the diseasecausing gene variant from that family’s lineage.
“By using this technique, it’s possible to reduce the burden of this heritable disease on the family and eventually the human population.”
There have been multiple attempts before, including, in 2015, teams in China using Crispr-technology to correct defects that lead to blood disorders.
But they could not correct every cell, so the embryo was a “mosaic” of healthy and diseased cells.
Their approach also led to other parts of the genetic code becoming mutated.
Those technical obstacles have been overcome in the latest research.
However, this is not about to become routine practice.
The biggest question is one of safety, and that can be answered only by far more extensive research.
There are also questions about when it would be worth doing - embryos can already be screened for disease through pre-implantation genetic diagnosis. (BBC)