THE results from the first CRISPR experiments done in the US on human embryos are now out, although the gene-editing technique has already been used in several human embryo studies conducted in China.
at Oregon Health and Science University and his colleagues used CRISPR to target a genetic mutation that causes thickening of the heart wall. The disorder can lead to heart failure, and is often behind the sudden deaths of apparently healthy young athletes.
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鈥淲e are still far away from doing CRISPR gene editing in the clinic, but this work takes us closer鈥�
For the study, the researchers recruited a male volunteer who carries the mutation. He provided the sperm to fertilise donated egg cells and create embryos.
Unlike in other similar experiments, the team injected the CRISPR-Cas9 gene-editing machinery while the eggs were being fertilised. They say this approach prevented mosaicism 鈥� a situation in which some of an embryo鈥檚 cells carry the edited gene, but the 鈥減roblem鈥� gene remains intact in other cells.
The team also found no evidence of unwanted edits elsewhere in the embryos (Nature, ). Such 鈥渙ff-target鈥� mutations are another reason why some researchers have expressed concern over using the technique in people.
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But of the Karolinska Institute in Stockholm, Sweden, who wasn鈥檛 involved in the study, points out that even with the researcher鈥檚 thorough analysis, it is hard to be sure that the treatment didn鈥檛 impact genes they didn鈥檛 specifically look at.
Even if it is safe, CRISPR is unlikely to be used to prevent inherited diseases like this heart condition. Genetic screening can already be used in IVF to select embryos that don鈥檛 carry these diseases. 鈥淲e are still far away from doing this in the clinic. But this work takes us closer,鈥� says Lanner.
This article appeared in print under the headline 鈥淯S embryos edited鈥�
