Scientists repair gene defect in embryo

WASHINGTON — In a first, researchers safely repaired a disease-causing gene in human embryos, targeting a heart defect best known for killing young athletes — a big step toward some day preventing a list of inherited diseases.

In a surprising discovery, the research team led by Oregon Health & Science University reported on Wednesday that embryos can help fix themselves if scientists jumpstart the process early enough.

It was laboratory research only, nowhere near ready to be tried in a pregnancy. But it suggests that scientists might be able to 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. And that raises ethical questions.

The new method uses the geneediting tool CRISPR to target a mutation in nuclear DNA that causes hypertrophic cardiomyopathy, a common genetic heart condition that can cause sudden cardiac death and heart failure.

The disease affects an estimated one in 500 people and can lead to heart failure and sudden death.

Researchers worked with healthy donated human oocytes, or egg cells, in ovaries that form an ovum and sperm carrying the genetic mutation that causes cardiomyopathy. Embryos created in this study were used to answer preclinical questions about safety and effectiveness.

“Every generation would carry on this repair because we’ve removed the diseasecausing gene variant from that family’s lineage,” said the senior author of the report, Shoukhrat Mitalipov, who directs the Center for Embryonic Cell and Gene Therapy at the university.

CRISPR stands for clustered regularly interspaced short palindromic repeats. It holds promise for correcting mutations to prevent other genetic diseases.