He Jiankui affair

The He Jiankui affair was the first and so far only case in which human embryos edited with CRISPR were transferred to a womb and carried to term. On 25 November 2018 the Shenzhen-based biophysicist He Jiankui announced through online videos and an exclusive news interview that twin girls, given the pseudonyms Lulu and Nana, had been born from embryos in which he had disrupted the CCR5 gene, intending to make them resistant to HIV. The reaction from the international scientific community was immediate and close to unanimous condemnation, and He was convicted of illegal medical practice thirteen months later.

§Background

He trained in physics in China, took a doctorate at Rice University, and did postdoctoral work at Stanford in single-molecule sequencing before returning to China in 2012 as an associate professor at the Southern University of Science and Technology in Shenzhen.¹ He founded sequencing companies and was, by 2017, working privately on embryo editing while formally on unpaid leave from the university.

The scientific setting mattered. CRISPR–Cas9 had made embryo editing technically accessible; Chinese groups had published the first reports of editing non-viable human embryos in 2015, finding low efficiency and pervasive mosaicism. An international summit in Washington that December had declared clinical germline use irresponsible until safety questions were resolved and there was broad societal consensus. Those were statements, not laws. China's rules in 2018 consisted of ministry guidelines from 2003 barring implantation of edited embryos, without criminal penalty attached.

§What happened

1. 2015
   The technique and the norm
   Chinese groups publish the first CRISPR experiments in non-viable human embryos; an international summit in Washington declares clinical germline use irresponsible pending safety and societal consensus.
2. 2017
   Recruitment
   He recruits couples in which the father is HIV-positive through a Beijing advocacy organisation, using consent documents framed around AIDS vaccine development.
3. 25 Nov 2018
   Announcement
   Online videos and a news exclusive reveal that twin girls have been born from embryos edited at the CCR5 locus.
4. 28 Nov 2018
   Hong Kong summit
   He presents the work at the Second International Summit on Human Genome Editing and discloses a second pregnancy. The organising committee condemns the experiment.
5. Jan 2019
   Investigation
   A Guangdong provincial inquiry concludes that he evaded supervision and used forged ethical review documents.
6. Dec 2019
   Conviction
   A Shenzhen district court sentences He to three years' imprisonment and a fine for illegal medical practice.
7. 2021
   New criminal law
   China creates a specific offence covering implantation of gene-edited or cloned embryos into humans or animals.
8. Apr 2022
   Release
   He is released from prison and resumes public activity, announcing further research projects.

He recruited couples through a Beijing HIV/AIDS advocacy organisation. In each, the prospective father was HIV-positive with suppressed viral load and the mother was HIV-negative. Embryos were created by intracytoplasmic sperm injection with the editing reagents co-injected, cultured, biopsied, and transferred.

The stated rationale was protection against HIV. It does not survive inspection. Sperm washing, a routine procedure, already reduces the risk of paternal transmission to close to zero, so the children were never at meaningful risk of acquiring HIV from their fathers. The edit was aimed at a hypothetical future infection — prophylaxis at best, and closer to the enhancement category discussed under Human enhancement than to treatment of a disease. Nor was there any condition to screen for: Embryo selection had nothing to select against, which removed the one situation in which editing is sometimes argued to add capability.

He announced the births days before he was scheduled to speak at the Second International Summit on Human Genome Editing in Hong Kong. He presented there on 28 November to a packed hall, defended the work, and revealed that a second pregnancy was under way. A third child was born from that pregnancy in 2019.

§What went wrong

The technical failures were as serious as the ethical ones.

Neither twin received the variant he was aiming at. The natural CCR5-Δ32 deletion, common in northern European populations and known to confer resistance to the most common HIV strains, is a specific 32-base-pair loss. Cas9 repairs by error-prone end joining produce whatever indels the cell happens to make. The twins carried novel mutations at the locus with no characterised function, not the protective allele. Installing a defined sequence rather than a random disruption is precisely what Base editing and Prime editing were developed to do: base editing was barely two years old when the embryos were made, and prime editing was not described until the year after the births.

At least one twin was mosaic. Different cells carried different edits, so no single genotype describes her. Excerpts from He's unpublished manuscript, released with expert commentary in 2019, showed that the biopsy data he relied on did not support the claims he made from them.²

Verification was impossible in principle. A trophectoderm biopsy samples cells destined for the placenta, and the embryo that is transferred is never itself sequenced — the structural obstacle to safe embryo editing described in Human germline editing. Reported off-target analysis was thin, and later work in human embryos revealed classes of damage at the target site that his methods would not have detected at all.

The consent process misrepresented the study. Documents described the project in the vocabulary of AIDS vaccine development and ran to more than twenty pages of technical material presented to couples with a strong incentive to accept. Ethics approval was attributed to a Shenzhen hospital that denied any involvement and said the signatures on the document were not authentic.

CCR5 loss is not free. People without functional CCR5 have elevated susceptibility to West Nile virus and other flavivirus infections. Trading a well-managed risk for a poorly characterised one is a bad exchange even if the edit had worked as intended.

Why the target choice damaged the case further

Disabling CCR5 is one of very few edits with an obvious protective rationale, which is exactly why it appealed. That the most defensible available target still produced an indefensible experiment is the affair's most useful lesson about the gap between a plausible idea and a justified intervention.

§Reaction

The summit's organising committee, chaired by David Baltimore, called the work irresponsible and said it had failed to conform to international norms.³ More than a hundred Chinese scientists signed an open letter condemning it. Jennifer Doudna, who had met He shortly before his presentation, described the work as shocking and used the episode to press for enforceable oversight. Journals declined the manuscript. His university dismissed him; his former doctoral adviser in the United States was investigated by his institution and subsequently left it. Legal scholars who reconstructed the sequence of decisions concluded that the failure was not of any single rule but of a system in which no rule had teeth.⁴

Dissent from the consensus was rare and narrow. George Church argued publicly that HIV prevention was a defensible target and that the pile-on was excessive, while criticising the execution. Almost no one defended the conduct of the experiment itself.

§Consequences

In December 2019 the Nanshan District People's Court in Shenzhen convicted He and two collaborators of illegal medical practice. He received three years' imprisonment and a fine of three million yuan; the others received shorter terms.⁵ The prosecution rested on practising medicine without a licence and forging approval documents, not on any statute about genome editing, because none then existed.

The verdict therefore turned on paperwork and licensure rather than on what had been done to the embryos, which is why the case is a poor precedent for anything except itself. Legislators noticed the gap: within three years China had written implantation of an edited embryo into its criminal code as an offence in its own right, and the wider rebuilding of Chinese oversight that followed is described in Governance of human genome editing. Internationally the episode hardened an argument that was already under way, between those who wanted a defined translational pathway on the grounds that a licensed route is safer than an unpoliced one, and those who read pathway-building as tacit endorsement — the same split that runs through the self-regulation model of the Asilomar Conference on Recombinant DNA.

The children's situation remains the least examined part of the story. Their health status is not public. No institution has acknowledged responsibility for the lifelong monitoring that an edited person plainly requires, and any such monitoring conflicts with their privacy and that of their families. They are the only human beings alive with deliberately edited nuclear genomes, a status they did not choose and cannot renounce.

§Aftermath

He was released in April 2022 and returned to public activity, announcing a series of projects — gene therapy for Duchenne muscular dystrophy, then embryo-editing research aimed at installing an Alzheimer's-protective variant — and cultivating attention on social media. He has published little that has passed peer review since, and his announcements are treated with widespread scepticism. Travel plans and academic invitations have repeatedly been withdrawn under pressure.

The affair is cited most often as evidence that scientific self-governance failed. A more precise reading is that it never applied. He was outside the academic system's incentives: privately funded, uninterested in publication, indifferent to reputation among peers. The mechanisms that constrain researchers — grants, journals, tenure, institutional review — had no purchase on him, and the mechanisms that eventually did were an ordinary criminal court and a medical licensing statute. That distinction matters increasingly as privately capitalised ventures announce similar ambitions, and it complicates the assumption behind both precautionary and pathway-based approaches that the relevant actors are members of a professional community in the first place.

§See also

• Human germline editing
• Governance of human genome editing
• CRISPR–Cas9
• Asilomar Conference on Recombinant DNA
• Designer babies
• Embryo selection
• Bioethics of enhancement
• Off-target effects in genome editing

§References