human embryos
August 3, 2017

Scientists use CRISPR to fix disease-causing mutation

Since the advent of the CRISPR gene-editing tool, there has been discussion that it could be used to alter human embryos to remove undesired pieces of DNA, and now, a group of researchers has done just that by correcting a mutation than can cause an inherited form of heart disease.

In what the New York Times called “a major milestone” that “raises the prospect that gene editing may one day protect babies from a variety of hereditary conditions,” doctors from Oregon Health and Science University and an international team of colleagues used CRISPR to fix a mutation in nuclear DNA that causes the common genetic heart disease hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy, the researchers explained in a statement, is a hereditary condition that causes sudden cardiac arrest or heart failure. However, by repairing the mutation responsible for the disease, they would be able to prevent it from being passed on to future generations.

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

‘Not the dawn of the era of the designer baby,’ experts emphasize

The study, which was published in the journal Nature, marks the first time that scientists in the US have conducted gene editing on human embryos, according to the Washington Post. Also, it marks the first time that this specific technique has been tested on donated human eggs, and may be the first step towards treating thousands of inherited diseases, BBC News added.

Dr. Mitalipov and his colleagues worked with healthy donated human oocytes and sperm which carried the genetic mutation for hypertrophic cardiomyopathy, the researchers said. The embryos created were allowed to develop for five days and used to investigate issues regarding the safety and effectiveness of the technique before the experiment was halted, according to reports.

Hypertrophic cardiomyopathy affects one in every 500 people and is caused by an error in a lone gene (an instruction in the DNA), according to BBC News. Anyone carrying the gene has a 50% chance of passing the defect on to their offspring, and the condition itself could cause the heart to suddenly stop beating. During the experiment, the doctors removed the disease-causing mutation during conception with a 72% success rate, the British media outlet noted.

Naturally, research of this nature will raise ethical questions and concerns over the creation of so-called “designer babies,” but as Dr. Mitalipov told the Washington Post, his team’s research should not be controversial, as they looked to “correct” mutant genes instead of modifying them. “Our program is towards correcting mutant genes,” the OHSU researcher explained.

“What this represents is a fascinating, important and rather impressive incremental step toward learning how to edit embryos safely and precisely,” said University of Wisconsin bioethicist Alta Charo, who was not involved in the study. “No matter what anybody says, this is not the dawn of the era of the designer baby,” she told the Post, explaining that desirable traits like intelligence or athleticism involve too many genes for doctors to be able to simply add them to a growing fetus.

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Image credit: OHSU