DNA breakthrough: Scientists repair genes in human embryos to prevent inherited diseases

In a major scientific breakthrough, researchers have harnessed a gene-editing tool to correct a disease-causing gene mutation in human embryos, preventing the mutation from passing to future generations.

In the stunning discovery, a research team led by Oregon Health and Science University reported that embryos can fix themselves if scientists jump-start the process early enough.

There was no indication how soon ordinary patients could take advantage of this technique.

The new technique, which was tested on clinical-quality human eggs, uses the CRISPR-Cas9 gene-editing tool to target a mutation in nuclear DNA that causes hypertrophic cardiomyopathy, according to the researchers. Hypertrophic cardiomyopathy is a common genetic heart disease that can cause heart failure and sudden cardiac death. The disease affects approximately 1 in 500 people and is a common cause of sudden heart failure in young people, particularly young athletes.

The research was published Aug. 2 in the journal Nature.

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While the procedure is nowhere near ready to be tried in a pregnancy, the research suggests that scientists might alter DNA in a way that protects not just one baby from a disease that runs in the family, but his or her offspring as well.

“Every generation on would carry this repair because we’ve removed the disease-causing gene variant from that family’s lineage,” said the report’s senior author, Dr. Shoukhrat Mitalipov, director of OHSU’s Center for Embryonic Cell and Gene Therapy, in a statement. “By using this technique, it’s possible to reduce the burden of this heritable disease on the family and eventually the human population.”

The research offers fresh insight into a technique that could apply to thousands of inherited genetic disorders affecting millions of people worldwide, according to the experts.

The team programmed the CRISPR-Cas9, which acts like a pair of molecular scissors, to find that mutation — a missing piece of genetic material. Researchers injected sperm from a patient with the heart condition along with those "molecular" scissors into healthy donated eggs at the same time. The scissors cut the defective DNA in the sperm.

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Normally, cells will repair a CRISPR-induced cut in DNA by essentially gluing the ends back together. Or scientists can try delivering the missing DNA in a repair package, like a computer's cut-and-paste program.

Instead, the newly forming embryos made their own perfect fix without that outside help, reported Mitalipov.

We all inherit two copies of each gene, one from dad and one from mom — and those embryos just copied the healthy one from the donated egg.

"The embryos are really looking for the blueprint," Mitalipov said in an interview with the Associated Press. "We're finding embryos will repair themselves if you have another healthy copy."

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It worked 72 percent of the time, in 42 out of 58 embryos. Normally a sick parent has a 50-50 chance of passing on the mutation.

Previous embryo-editing attempts in China found not every cell was repaired, a safety concern called mosaicism.

Experts have lauded the study as a major leap forward in genetic research.

“This is incredibly important work,” CRISPR expert and professor at Harvard and MIT George Church told Fox News, via email. “Few people realize how common are genetic diseases.”

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Church, who is not affiliated with the research, noted that genetic diseases affect about five percent of births, causing great suffering. “The mainstream medical approaches today kill embryos and this offers a route to avoid that be (a process of) engineering the eggs,” he explained. “Shoukhrat Mitalipov's team has made two huge breakthroughs in efficiency and precision.”

The researchers behind the study say that the gene-editing technique, which was done in concert with in vitro fertilization, could also increase the success of IVF by increasing the number of healthy embryos.

“If proven safe, this technique could potentially decrease the number of cycles needed for people trying to have children free of genetic disease,” said report co-author Dr. Paula Amato, associate professor of obstetrics and gynecology in the OHSU School of Medicine, in a statement.

While gene editing holds great potential for the battle against genetic diseases, it has, however, prompted fears that it could be harnessed for “designer babies.”

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The scientists behind the breakthrough study noted that their research is consistent with recommendations issued earlier this year by the National Academy of Sciences and the National Academy of Medicine joint panel on human genome editing.

The recommendations laid out three major settings where gene editing can be used in biomedicine: basic research on human disease and its treatment, clinical applications to prevent disease or disability in non-productive cells and clinical applications to prevent disease or disability in productive cells.

The Associated Press contributed to this article. Additional reporting by Chris Ciaccia.

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