The controversial 2018 announcement by Chinese scientist He Jiankui that he had created the world’s first gene-edited human babies sent a shockwave across the globe. This event ignited an international debate over the boundaries of human genetic modification. He Jiankui’s claim of successfully altering the DNA of human embryos before birth made the theoretical possibility of human germline editing a reality. The unauthorized nature of the experiment and the potential long-term consequences for the children were the catalysts for global condemnation.
Understanding the Technology Used
The technology utilized in the experiment was CRISPR-Cas9, a sophisticated genome editing tool that allows scientists to precisely alter DNA sequences. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats, a mechanism repurposed from bacteria for genetic engineering. The Cas9 enzyme acts as “molecular scissors,” guided by RNA to a specific location in the DNA sequence where it makes a precise double-stranded cut.
The cell’s natural DNA repair mechanisms then attempt to fix this break, allowing scientists to introduce an alteration, such as inactivating a gene. He Jiankui targeted the CCR5 gene, which produces a protein that HIV uses as a “doorway” to enter and infect T-cells.
Disabling the CCR5 gene was intended to mimic a naturally occurring mutation, CCR5-Δ32, which results in a nonfunctional protein. Individuals with two copies of this natural mutation are highly resistant to the most common strains of HIV. The goal of the editing procedure was to confer this same resistance to the twin girls by disrupting the CCR5 gene in their embryos.
The Specifics of the Unsanctioned Experiment
The experiment recruited couples where the father was HIV-positive and the mother was HIV-negative. Existing medical procedures already offered a near-zero risk of transmitting the virus to the child in such cases. The embryos were created using in vitro fertilization (IVF), and the CRISPR-Cas9 components were injected into the fertilized eggs at the single-cell stage. The procedure took place in 2018 in Shenzhen, China, without the required institutional or national ethical oversight.
The edited embryos were implanted, resulting in the birth of twin girls, Lulu and Nana, in October 2018. He Jiankui announced the births publicly via YouTube videos shortly thereafter. The announcement revealed that the editing was not a clean recreation of the natural CCR5-Δ32 mutation. Furthermore, the twins were genetic mosaics, meaning the modification was inconsistent across their cells. One twin had both copies of the gene modified, but the other had only one, leaving her susceptible to HIV infection.
Why the World Reacted So Strongly
The global reaction stemmed primarily from the unprecedented step of performing germline editing for reproductive purposes. Germline editing involves making genetic changes in embryos, meaning the alterations are heritable and will be passed down to all future generations. This permanence of change introduces unknown, irreversible long-term effects on the human gene pool.
The scientific community found the intervention medically unnecessary, as safe methods already exist to prevent HIV transmission. Exposing healthy embryos to the unpredictable risks of an unproven technology was unjustifiable. These risks included “off-target effects,” where the CRISPR tool cuts DNA at unintended locations, potentially causing new diseases or other unforeseen genetic problems.
Scientists also noted that the CCR5 gene is involved in other biological functions, including resistance to other viruses and potentially cognitive function. The attempt to confer HIV resistance was a trade-off, potentially making the children more susceptible to infections like West Nile virus or severe influenza. The consensus was that the modest benefit of HIV resistance did not outweigh the risks imposed on the children.
Legal Ramifications and Monitoring
Following the announcement, Chinese authorities launched an investigation and suspended all of He Jiankui’s research activities. The investigation concluded that He and his collaborators had deliberately violated national regulations on scientific research and medical ethics, including forging documents to recruit couples. The Chinese court found He Jiankui guilty of “illegal practice of medicine,” a serious criminal offense.
He Jiankui was sentenced to three years in prison and a substantial fine. Two of his collaborators, Zhang Renli and Qin Jinzhou, also received lesser sentences, including prison time and fines. The court emphasized that the trio had acted “in the pursuit of personal fame and gain” and lacked the proper qualifications to conduct the medical procedures.
The legal consequences included a perpetual requirement to monitor the health and development of the children: Lulu, Nana, and a third child born later from a similar procedure. Their current status and location remain protected and confidential to ensure their privacy. The Chinese government and He Jiankui’s former university are tasked with ensuring the children receive necessary long-term medical support and monitoring to track any potential effects of the genetic modifications.