Global scientists on Thursday renewed calls to halt controversial research to genetically edit human embryos after a Chinese team published details of a stunted but breakthrough attempt in this new frontier in science. First reported by Nature News on Wednesday, the paper by Junjiu Huang, a gene-function researcher at Sun Yat-sen University in Guangzhou, and colleagues appears in a little known online journal called Protein and Cell.
In it, researchers describe how they edited the genomes of embryos obtained from a fertility clinic. The embryos were non-viable, and could not have resulted in a live birth because they had an extra set of chromosomes after being fertilised by two sperm. Researchers "attempted to modify the gene responsible for beta-thalassemia, a potentially fatal blood disorder, using a gene-editing technique known as CRISPR/Cas9," said the report in Nature News.
The researchers injected 86 embryos and waited 48 hours for the molecules that replace the missing DNA to act. Seventy-one embryos survived, and 54 of those were tested. Researchers found that only 28 were "successfully spliced, and that only a fraction of those contained the replacement genetic material," said the report.
"If you want to do it in normal embryos, you need to be close to 100 percent," Huang was quoted as saying. "That's why we stopped. We still think it's too immature." Even more concerning were the "surprising number" of unintended mutations that arose in the process, at a rate far higher than seen in previous gene-editing studies using mice or adult human cells. Such mutations can be harmful, and are a key reason for concerns raised in the scientific community ever since rumours of the Chinese team's research began circulating earlier this year.
Critics say the science could have unknown effects on future generations, and could open the door to a new era of eugenics by altering humans so they carry potentially desirable traits. In reaction to the report, the Alliance for Regenerative Medicine renewed its call for a halt to the research, according to an email sent to AFP. "Given the significant safety and ethical implications of modifying the DNA of human reproductive (germline) cells, this research is highly premature," said the statement from the international organisation which represents more than 200 life-sciences companies, research institutions and advocacy groups that are focused developing therapeutics, including those involving genome editing.