For the first time outside of China, scientists have successfully modified human embryos— in this case, removing genetic mutations that cause heart failure in otherwise healthy young people—using a controversial procedure, reports Pam Belluck.

Chinese researchers have already conducted several small studies to determine whether gene editing could be used to prevent normally inherited diseases from being passed on to the next generation.

“It feels a bit like a ‘one small step for (hu)mans, one giant leap for (hu)mankind’ moment,” Jennifer Doudna, a biochemist who helped discover the gene-editing method used, called CRISPR-Cas9, told The Times in an email.

But this major scientific breakthrough also renews ethical concerns that “some might try to design babies with certain traits, like greater intelligence or athleticism,” notes Belluck.

According to The Guardian:

Crispr, or to give it its full name, Crispr-Cas9, allows scientists to precisely target and edit pieces of the genome. Crispr is a guide molecule made of RNA, that allows a specific site of interest on the DNA double helix to be targeted. The RNA molecule is attached to Cas9, a bacterial enzyme that works as a pair of “molecular scissors” to cut the DNA at the exact point required. This allows scientists to cut, paste and delete single letters of genetic code. 

A National Academy of Sciences, Engineering and Medicine committee endorsed embryo modification in February, says Belluck, but only to repair a mutation that would lead to “a serious disease or condition” and when no “reasonable alternatives” exist.

Read more at The New York Times


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