If we could edit the DNA of our future children to make them more resistant to viruses, or less likely to develop certain cancers, should we be allowed to do it? This question has been a recent topic of debate ever since two groups of scientist from China used a relatively new gene editing technique called CRISPR/Cas9 to edit the DNA of human embryos.
Scientists have been able to edit the DNA content of plants, flies and mice for decades, however the techniques of the past have never been as precise and simple as CRISPR/Cas9. This three-year old technique allows scientist to cut and paste pieces of DNA and has already been used to stop cancer cells from multiplying and make genetically modified wheat resistant to killer fungi.
The technique was never used to alter human embryos, that is not until 2015, when a group of scientist from The Laboratory for Major Obstetric Diseases at the University in Guangzhou, China reported modifying a gene associated with a blood disorder in human embryos.
This report sparked a heated debate on the ethical consequences of such work, which was recently further ignited when a second group of Chinese scientists revealed results of similar experiments in April of this year.
In this new study, a group of scientist led by Dr. Yong Fan collected flawed human embryos and attempted to make them resistant to HIV. The embryos were donated by 87 patients, and could not be used in fertility treatments as they contained an extra set of chromosomes, and were unable to survive longer than 3 days.
Using the gene editing technique CRISPR/Cas9, the scientists attempted to cripple the gene CCR5 required by HIV to enter and infect immune cells. This type of mutation in the CCR5 gene is naturally found in Northern European populations and humans that carry it are resistant to HIV infection.
According to the results, only 4 out of 26 targeted human embryos were found to carry the HIV-resistant mutation of CCR5. However, in each of those 4 embryos only one of the two copies of CCR5 was modified correctly, while the second copy was either unaltered, or contained undesired mutations. Therefore, although the CRISPR/Cas9 is suitable for altering human DNA, it is far from having the outcome required if the technique is to be used to genetically engineer embryos intended for implantation into women’s bodies.
Although it may not be difficult to imagine that limitation of gene editing tools will be overcome in the near future, the legal and moral dilemmas still persist. Fixing simple genetic mutations known to cause disease may not lead to obvious problems, however inserting new sequences could potentially lead to negative consequences we have no way of predicting. Should we as parents have the right to consent to these types of changes, which will ultimately affect our children who had no input in the matter? The bottom line is that although the technology for editing human embryos is still not advanced enough, the legal and ethical issues must be addressed prior to the advancement of such tools.
For now, scientists agree that editing genes of human embryos should only be used for advancement of science, and not for alteration of embryos used in fertility treatments. Hopefully, by the time creation of genetically modified humans becomes technically feasible, adequate rules and regulations will already be protecting our future generations.