Human embryo editing breakthrough could eradicate thousands of inherited diseases
Scientists have successfully managed to alter DNA in defective human embryos in order to remove a genetic mutation, in a groundbreaking move that could open the door to preventing some 10,000 inherited disorders in future.
The development came as a result of a study in the US which saw scientists use a powerful gene-editing tool called Crispr-Cas9 to fix a mutation responsible for inherited heart failure by replacing faulty DNA.
At it simplest the Crispr-Cas9 cuts away precisely targeted elements of DNA from within a cell and then natural repair systems kick in to try to repair the damage.
In more advanced cases additional "template" DNA can be added to a cell which can then be used to mend the break and make it possible to re-write the genetic code.
Why is this development important?
The controversial technique used to correct the embryos is still at an early experimental stage but potentially it could be used to fix more than 10,000 heritable conditions that are caused by an error in a single gene.
Dr Shoukhrat Mitalipov, one of the lead scientists working on the study at Oregon Health and Science University (OHSU) in Portland, explains that by using their technique to fix defective gened "it's possible to reduce the burden of this heritable disease on the family and eventually the human population."
He said: "Every generation on would carry this repair because we've removed the disease-causing gene variant from that family's lineage."
How was the study carried out?
In the study, the details of which were published in the journal Nature, the genetic repair was carried out on donor eggs which were fertilised with sperm containing the defective gene.
At this early stage of conception scientists then applied the gene-editing tool, which acts like a pair of precisely targeted genetic scissors, to snip away the defective elements of the gene.
Nature is then said to have kicked with the embryo's own cellular repair systems replacing the removed elements with healthy versions.
Forty two out of 58 embryos (72.4%) were correctly fixed and were found to no longer carry the heart failure mutation, which normally has a 50% chance of being passed on.
How will the US study affect the UK?
According to Dr Mitalipov, Britain has the potential to become the country which will pioneer bringing this treatment to patients under the direction of the fertility regulator the Human Fertilisation and Embryology Authority (HFEA).
He said: " Maybe .. (the) HFEA might take a lead on this, but I'm quite sure before these clinical trials can go on they have to go through, I believe, Parliament to change a law. So there is still a long road ahead, particularly if you want to do it in a regulatory way."
The highly controversial technique is still at an early experimental stage though and Dr Mitalipov made clear there is no question of any attempt being made to create babies with the genetic modification - something which would be illegal in the US and the UK.