Human embryo 'editing' sparks international debate

Beijing: In a world’s first, Chinese scientists have reported “editing” the genomes of human embryos. The results confirm widespread rumours that such experiments had been conducted in China.

These rumours sparked a high-profile debate recently about the ethical implications of such work, the scientific journal Nature reported, citing the study that first appeared in the journal Protein & Cell.

In the paper, researchers led by Junjiu Huang, a gene-function researcher at Sun Yat-sen University in Guangzhou, used “non-viable” embryos [which cannot result in a live birth] that were obtained from local fertility clinics.

The team attempted to modify the gene responsible for I-thalassaemia, a potentially fatal blood disorder using a gene-editing technique known as CRISPR/Cas9. “I believe this is the first report of the gene-editing technique applied to human pre-implantation



embryos. The study is a landmark one as well as a cautionary tale,” said George Daley, stem-cell biologist at Harvard Medical School in Boston.

Some say that gene editing in embryos could have a bright future because it could eradicate devastating genetic diseases before a baby is born.

Others say such work crosses an ethical line. The technique used by Huang’s team involves injecting embryos with the enzyme complex CRISPR/Cas9, which binds and splices DNA at specific locations.

They studied the ability of the CRISPR/Cas9 system to edit the gene called HBB, which encodes the human I-globin protein. Mutations in the gene are responsible for I-thalassaemia. The team injected 86 embryos and then waited 48 hours, enough time for the CRISPR/Cas9 system and the molecules that replace the missing DNA to act — and for the embryos to grow to about eight cells each.