In a world first, Chinese scientists have reported editing the genomes of human embryos. The results are published in the online journal Protein and Cell and confirm widespread rumours that such experiments had been conducted—rumours that sparked a high-profile debate last month about the ethical implications of such work.
In the paper, researchers led by Junjiu Huang, a gene-function researcher at Sun Yat-sen University in Guangzhou, tried to head off such concerns by using '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 β-thalassaemia, a potentially fatal blood disorder, using a gene-editing technique known as CRISPR/Cas9. The researchers say that their results reveal serious obstacles to using the method in medical applications.
"I believe this is the first report of CRISPR/Cas9 applied to human pre-implantation embryos and as such the study is a landmark, as well as a cautionary tale," says George Daley, a stem-cell biologist at Harvard Medical School in Boston. "Their study should be a stern warning to any practitioner who thinks the technology is ready for testing to eradicate disease genes.
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 that such work crosses an ethical line: researchers warned in Nature in March that because the genetic changes to embryos, known as germline modification, are heritable, they could have an unpredictable effect on future generations. Researchers have also expressed concerns that any gene-editing research on human embryos could be a slippery slope towards unsafe or unethical uses of the technique.
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. Of the 71 embryos that survived, 54 were genetically tested. This revealed that just 28 were successfully spliced, and that only a fraction of those contained the replacement genetic material. “If you want to do it in normal embryos, you need to be close to 100%,” Huang says. “That’s why we stopped. We still think it’s too immature.”
His team also found a surprising number of ‘off-target’ mutations assumed to be introduced by the CRISPR/Cas9 complex acting on other parts of the genome.
A Chinese source familiar with developments in the field said that at least four groups in China are pursuing gene editing in human embryos.
An interview with Geoffrey Miller, an evolutionary psychologist and lecturer at NYU, at Vice shows that there is a difference in cultural attitude to genetic enhancement of children between Asia and the West
We have ideological biases that say, “Well, this could be troubling, we shouldn’t be meddling with nature, we shouldn’t be meddling with God.” I just attended a debate in New York a few weeks ago about whether or not we should outlaw genetic engineering in babies and the audience was pretty split. In China, 95 percent of an audience would say, “Obviously you should make babies genetically healthier, happier, and brighter!” There’s a big cultural difference.
There was other progress identifying the genes to enhance intelligence
Molecular Psychiatry - Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium
General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53 949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32.
The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10−17). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer’s disease: TOMM40, APOE, ABCG1 and MEF2C.
Stephen Hsu posted on the main genetic findings on intelligence. Stephen Hsu has written extensively on the genetic basis on intelligence and the near future of embryo selection. Stephen advises BGI the main genomics company of China.
There was a review of five years of genome-wide association studies in 2011.
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