A new technique could allow scientists to edit and repair the human genome, and perhaps one day treat diseases or conditions linked to our genes.
Researchers have figured out how to use the gene-editing tool known as CRISPR-Cas9, on the messenger RNA that carries genetic instructions from the cell's nucleus to make new proteins.
The experiment, by scientists at the University of California, San Diego, could lead to new treatments for diseases caused by malfunctions in the messenger RNA, such as fragile X syndrome, some types of cancer, autism and neurodegenerative diseases.
"Now we have the ability to modify RNA in live cells," said Gene Yeo, associate professor of molecular medicine at UCSD and a senior author on the study published today in the journal Cell.
Yeo's team figured out a new way of targeting and tracking RNA as it moves through human cells.
"It opens up a new area of thinking about manipulating genes and disease," he said. "In many diseases you cannot edit the genome, you can break the genome into pieces. But here we are doing transcription engineering or editing. That's quite exciting."
Efforts to edit and measure DNA got a big boost a few years ago when researchers discovered they could take CRISPR-Cas9, a naturally occurring defense mechanism bacteria use to fend off invading bacteria, and apply it to edit genes.
CRISPR-Cas9 is like a super-precise pair of genetic scissors.
Normally, CRISPR-Cas9 works like this: Researchers design a "guide" RNA to match the sequence of a specific target gene. The RNA directs the Cas9 enzyme to the desired spot in the genome, where it cuts the DNA. The cell repairs the DNA break imprecisely, thus inactivating the gene, or researchers replace the section adjacent to the cut with a corrected version of the gene.
Because genes have a huge influence on the way we look, our health and perhaps our personality, the prospect of getting rid of certain genes has also opened the door to fears of parents wanting to create "designer babies" using CRISPR-Cas9.
Last year, Chinese researchers stirred up an ethical hornet's nest when they altered human embryos to get rid of a lethal blood disorder. The embryos were not viable, by the experiment prompted many scientists to call for a moratorium on such experiments until ethical guidelines could be put into place.
The U.S. government forbids federal funding for gene-editing on human embryos. In the meantime, the National Academy of Sciences is working on a set of ethical rules that will guide research in this rapidly growing field.
One benefit of doing gene-editing on RNA instead of DNA is that it might bypass some of the ethical concerns about altering our genetic code, according to Eric Lecuyer, director of the RNA biology laboratory at the Montreal Institute of Clinical Research (IRCM).
"With all the controversy over the ethics of genome editing, the RNA molecules are not thought to contribute to the genomic pedigree of an individual," Lecuyer said. "It's less controversial to target RNA molecules and until the (CRISPR-Cas9) technology gets mature, this is probably going to be a more attractive way to do therapeutic approaches to these disorders."