Scientists reported selectively altering genes in viable human embryos for the first time this year. For nearly five years, researchers have been wielding the molecular scissors known as CRISPR/Cas9 to make precise changes in animals’ DNA. But its use in human embryos has more profound implications, researchers and ethicists say.
“We can now literally change our own species,” says Mildred Solomon, a bioethicist and president of the Hastings Center, a bioethics research institute in Garrison, N.Y.
CRISPR/Cas9 is a bacterial immune system (SN: 4/15/17, p. 22) turned into a powerful gene-editing tool. First described in 2012, the editor consists of a DNA-cutting enzyme called Cas9 and a short piece of RNA that guides the enzyme to a specific spot that scientists want to edit. Once the editing machinery reaches its destination, Cas9 cleaves the DNA. Cells can repair the break by gluing the cut ends back together, or by pasting in another piece of DNA. Scientists have developed variations of the editor that make other changes to DNA without cutting, including one version described in October that performs a previously impossible conversion of one DNA base into another.
Whether scientists should use CRISPR/Cas9’s power to create gene-edited babies is a matter of heated debate. Until March, the battles were mostly academic because previous attempts to edit human embryos were done in embryos that would never develop into a baby (SN Online: 4/8/16; SN Online: 4/23/15). But in March, Lichun Tang of China’s Beijing Proteome Research Center and colleagues reported using CRISPR/Cas9 to correct disease-causing mutations in a small number of viable human embryos. Other groups posted separate reports of CRISPR/Cas9 repair in viable human embryos in August and October.
Read more: https://www.sciencenews.org/article/crispr-gene-editing-top-science-stories-2017-yir
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