Scientists have just achieved a massive breakthrough by successfully modifying the DNA in human embryos without introducing harmful mutations. An international team of scientists has published a paper in the journal Nature detailing a way to edit DNA, which could help stop genetic diseases dead in their tracks.

Scientists used a gene-editing technique to correct a genetic defect that can cause a heart disorder in young people. They were able to correct the defect in an astonishing two thirds of embryos, all without causing a mutation that could prove dangerous.

If the technique could be confirmed through further tests to be safe and effective, it could be used in the future to stop genetic diseases that plague mankind.

“Genome editing has potential for the targeted correction of germline mutations,” the abstract of the paper states. “Here we describe the correction of the heterozygous MYBPC3 mutation in human preimplantation embryos with precise CRISPR–Cas9-based targeting accuracy and high homology-directed repair efficiency by activating an endogenous, germline-specific DNA repair response.

“Induced double-strand breaks (DSBs) at the mutant paternal allele were predominantly repaired using the homologous wild-type maternal gene instead of a synthetic DNA template,” it continues. “By modulating the cell cycle stage at which the DSB was induced, we were able to avoid mosaicism in cleaving embryos and achieve a high yield of homozygous embryos carrying the wild-type MYBPC3 gene without evidence of off-target mutations. The efficiency, accuracy and safety of the approach presented suggest that it has potential to be used for the correction of heritable mutations in human embryos by complementing preimplantation genetic diagnosis. However, much remains to be considered before clinical applications, including the reproducibility of the technique with other heterozygous mutations.”