A Nobel scientist said his “jaw dropped” when he saw for himself this intensely exciting breakthrough in DNA development. Heralded as a radical, and game-changing milestone in medical science, it will bring a revolution in treatments of major disease, even incurable inherited conditions like Down Syndrome and sickle-cell anemia, cancers and HIV infection.
The technique, called Crispr, was derived from bacteria. It works by attaching an enzyme, CAS9 to an RNA “guide” molecule. This then accurately targets the specific DNA sequence, cutting the exiting strands of the helix. From this point, either defective DNA is eliminated or a new DNA can be inserted. It is phenomenally precise. CAS9 acts as a cutting enzyme that snips the DNA with supreme accuracy.
Professor Craig Mello, winner of the Nobel Prize for Medicine in 2006 for his work on RNA, spoke from the University of Massachusetts Medical School, exuberant at the news, “It’s a tremendous breakthrough with huge implications for molecular genetics.” Mello said you had to see it to believe it, but when one of his own lab novices performed the technique faultlessly, he saw that what he had read in the scientific journals was correct. “My jaw dropped” he confessed.
“Crispr is absolutely huge,” Mello declares. “This is really a triumph of basic science.” He predicts it will have applications from human gene therapy through to agriculture.
“I’m jumping out of my skin with excitement,” said another eminent scientist, George Church, of Harvard University. “The efficiency and ease of use is completely unprecedented.”
The gene-editing technique has been compared to editing the pages of an encyclopedia, without any spelling mistakes. The precision allows the most accurate alterations to be made to any of the 23 pairs of chromosomes on the DNA without error. Where previously there was always the chance of inadvertently introducing a mutation or a flaw, by tampering with the code, this is no longer a risk.
It is really as simple and easy as editing a word document on a computer. The genetic alphabet, made up of nucleotides, can be edited at any individual point.
Trials are expected to begin immediately to test the gene-therapy on incurable genetic disorders, like Huntington’s disease. More controversially, there are implications for the elimination of inherited disease in IVF embryos.
The prospect of so-called “designer babies” has been a moral and ethical dilemma in science for some time, and germline gene-therapy practice is illegal in many countries. Crispr, though, with its accuracy, addresses a lot of the safety issues. Families, and all their descendants, could be rid of inherited disease. It would simply be a matter of altering the DNA in the embryo before implantation into the womb.
Professor Church, at Harvard, said “This could be done, in principle, at any stage of development from sperm and egg cells and IVF embryos.”
An IVF specialist at Oxford University, Dagan Wells, says it will be “difficult to argue against using it if it can be shown to be as safe, reliable and effective as it appears to be.” He goes on to comment “Who would condemn a child to terrible suffering and perhaps an early death when a therapy exists.”
Craig Mello is a little more cautious on this topic, saying that although it “lowers the threshold” for conducting gene therapy on human embryos, using it in IVF could still be “some way off” because of potential “unintended consequences.”
GM modifications to crops and livestock are another area of research expected to benefit from CAS9-Crispr techniques in time. It is the implications of the radical and game-changing technique to tackle incurable human conditions that is generating the most current excitement.
Genetic scientists have already worked with it on mice and are astonished at its accuracy in altering the DNA of any life form. It is the therapeutic potential for cutting out mutations that cause inherited disease, cancer, or HIV that is the most transformative breakthrough.
“Individual patient mutations can be corrected” said Dr David Adams, a DNA expert at the Wellcome Trust Sanger Institute. Technology to genetically edit the genome has been around for considerable time but not with this level of precision. There was always the danger of leaving “a “scar” behind, or foreign DNA in the genome.” What makes Crispr different, radical and revolutionary is that “you can change the individual nucleotides of DNA – the “letters” of the genetic textbook” and no unwanted changes will occur.
It was Jennifer Doudna and her team at the University of California who led the ground-breaking research. She identified Crispr initially as an immune defense by bacteria against invasive viruses. She then published the study detailing how CAS9 could cut any region of a genome with unparalleled precision. This was last year. Since then, teams of scientists have tested, and proven the Crispr technique. They are all astounded and excited. It truly is “jaw-dropping” news.
Doudna picked up research from Japan conducted in 1987, that was dismissed at the time. Crispr stands for “clustered regularly interspaced short palindromic repeats.”
Crispr could well be the most radical game-changer yet discovered in genetic science to tackle hitherto incurable conditions.
By Kate Henderson