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Human embryo gene editing has taken place in US

A fourth paper on attempts to correct defective genes in human embryos using CRISPR will be published. According to a report in MIT Tech Review, the results are the most promising so far.

Many groups around the world are working on gene editing in human embryos usign the CRISPR technique. Some of them want to do this in order to study embryonic development and improve fertility treatments, while others want to explore its potential for correcting genetic diseases.

A team led by Shoukhrat Mitalipov of Oregon Health and Science University is about to publish details of a bigger study based on editing “many tens” of embryos, according to New Scientist. Back in 2013, Mitalipov was the first to derive stem cells from human embryos created by cloning adult cells.


The team had reportedly made progress in tackling the biggest safety issue – that of mosaicism. Mosaicism occurs when genome editing does not take place until after the DNA of a fertilised egg has begun to divide. This way, just some cells in the resulting embryo have the desired change; what’s more, any resulting children might still develop the disease that was to be prevented. High rates of mosaicism were seen in the first three CRISPR human embryo studies. Mitalipov’s team has managed to reduce the rate of mosaicism by injecting the CRISPR machinery at an earlier stage than usual, right when the eggs were fertilised with sperm.

Another issue with using genome editing to correct genetic diseases is that there is little need for it. The majority of serious genetic diseases – like cystic fibrosis – can already be prevented by screenings and generating several embryos by IVF and implanting the ones that don’t carry a genetic disease.

Daisy Wilder