Embryo first in bid to fix faulty genes
HEALTH: A study has raised the prospect of Britain pioneering the use of human embryo gene editing to eradicate inherited diseases. Scientists in the US reached a new milestone by successfully altering DNA in defective embryos.
A LANDMARK study has raised the prospect of Britain pioneering the use of human embryo gene editing to eradicate inherited diseases.
Scientists in the US reached a new milestone by successfully altering DNA in defective embryos so they were no longer programmed to develop heart failure.
It is the first time the powerful gene-editing tool Crispr-Cas9 has been used to fix a mutation responsible for a common inherited disease.
The highly controversial technique is still at an early experimental stage and there is no question of any attempt being made to create babies with the genetic modification, which would be illegal both in the US and the UK.
But a leading member of the team has hinted that first steps towards bringing the treatment to patients could take place in the UK under the direction of the fertility regulator the Human Fertilisation and Embryology Authority (HFEA).
Dr Shoukhrat Mitalipov, from Oregon Health and Science University (OHSU) in Portland, said: “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 treatment replaces faulty inherited DNA in the mitochondria, tiny rod-like bodies in cells that supply energy, to prevent devastating diseases. However, the new research reported in the journal, Nature, goes much further by modifying the nuclear DNA at the heart of the cell that influences personal characteristics such as height, facial appearance, eye colour and intelligence.
Leaked information has already led to widespread speculation about the study. The published paper explains how Crispr-Cas9 was used to repair human embryos blighted by a single copy of a mutant gene, MYBPC3, that causes hypertrophic cardiomyopathy, a type of heart failure.
Using standard IVF techniques, the scientists first fertilised donor eggs with sperm containing the defective gene. At the time of fertilisation, they applied the gene-editing tool that acts like a pair of precisely targeted genetic scissors. Once the defective elements of the gene had been snipped away, the embryo’s own cellular repair systems replaced them with healthy versions.
Nature stepped in at this point, by using the egg donor’s properly functioning MYBPC3 gene as a template on which to base the repair. Forty-two out of 58 embryos were correctly fixed so that they no longer carried the heart failure mutation, which normally has a 50 per cent chance of being passed on.
Dr Mitalipov said: “Every generation on would carry this repair because we’ve removed the disease-causing 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.”
Dr Mitalipov said the same technique could be used to repair the faults responsible for any of these disorders. He also wanted to explore the possibility of targeting cancer mutations. Before clinical trials could be considered, the technique would have to be made more efficient and further checks would have to be made to ensure its safety, he said.
“I’m quite sure there are tools we could use to improve the repair to 90 - 100 per cent efficiency and then we will be ready to move to clinical trials,” added Dr Mitalipov.