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

The research team led by Oregon Health and & Science University is reporting that embryos can help fix themselves if scientists jump-start the process early enough.

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It's laboratory research only, nowhere near ready to be tried in a pregnancy. But it's a step toward altering DNA in a way that protects not just one baby from an inherited disease, but his or her offspring as well.

Genetics experts are praising the study and say it's time for an ethical debate on how far such research should go.

The study was published in the journal Nature.

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