she died of a severe immune reaction linked to the therapy

Yeah that's something that should have been tested for prior to actually starting the therapy.

Blinded by fame and greediness

How? I mean the way every drug for example is tested for safety, they give it to people (healthy volunteers) in escalating doses, and watch them for adverse effects.
Rarely, it happens that a drug that was expected to be safe based on animal testing turns out to be dangerous in humans, and healthy volunteers die. It’s a tragedy, it happens rarely, but it happens, and safety trials are still the best way to start the process of clinical trials for new drugs.
For some treatments, such as gene therapy, it’s not ethical to ask a volunteer to just try it to see if it’s safe. So they look for sick people, who are consenting to risking a new treatment with unproven safety, because their other choice is to not be treated.
This is how it’s always done. I wonder what you mean when you say the treatment should be tested for safety before giving it to patients.

Edit: this was a personalized experimental treatment developed specifically for this girl, on the parents’ initiative. The clinical team did test for antibodies against the virus before injecting the AAV into the csf. Lots of shady and wrong things on the research side, I’m not protecting them, just disagreeing with the previous comment that this tragedy would have been prevented by a simple test.

A virus that doesn't actually do anything is how. Or a test injection that doesn't have any virus at all, if the reaction was to something else in it.

Neither of those things is what the patient received. Do you mean they should test the vector without the payload on the patient? If the adverse reaction is to the vector, the patient would then experience the negative effects without a chance of getting any benefits. So why not give the real thing then?
If you mean a control vector should be tested on healthy volunteers, idk, maybe, but it’s hard to come up with a relevant control that certainly doesn’t do anything to dna.

If the adverse reaction is to the vector, the patient would then experience the negative effects without a chance of getting any benefits.

Yeah but she wouldn't be fucking dead.

Wtf. If she died from the dna editing, doing the test you mention wouldn’t have prevented it. If she died from the formulation, she would have died from the test you talk about. I don’t see a scenario where a test with a control virus makes a difference.

An allergy test uses small amounts to test for a reaction.

She died in kidney failure and thrombotic microangiopathy, not an allergic reaction. They did test for antibodies against the virus. The injection was directly into the cerebrospinal fluid, not exactly the same exposure you get with a skin allergy test.

It has to be the exact virus or it's irrelevant, and it kind of can't be done.

The virus has to get to the brain and spread around and "infect" cells in order to edit the DNA. It's why it had trillions of the virus. It needs a slow and unprepared immune response so it can do the editing.

If they did a small dose test, you just vaccinated her against the virus. Her immune system would more quickly go after and destroy the virus. They expected her to get sick. They didn't expect it to get that bad. She needed more powerful immunosuppressants beforehand.

This is sad, but its going to happen quite a few more times before they really understand large scale gene editing. And even after they do understand it better, probably some percentage of the time its gonna go wrong.

Turns out they did on both mice and primates, and the side effect is also evaluated:

Another potential concern, however, emerged about 1 month before Mei was treated: the final conclusions of a primate toxicology study conducted at PriMed. The company’s report, dated 17 February 2025, concluded all four monkeys that received the therapy, whether at low or high doses, developed moderate to severe liver damage.

However, the ethics board did not review the safety report:

An ethics panel at Xinhua Hospital in China approved a gene-editing trial, but had not reviewed primate data suggesting safety concerns. Another hospital panel later concluded the experimental treatment was “definitely related” to Mei’s death.

Even worse, the brain development data from the primate study is entirely unconvincing:

But four of the experts Science asked to assess this figure, including one of the original reviewers of the Nature manuscript, expressed concerns about how well the primate proof-of-concept study was conducted. The submitted paper had no control samples to show the stain was selectively highlighting the gene editor. “It’s completely unconvincing,” says David Sanders, a biochemist at Purdue University who has studied gene therapy. “One can’t have the confidence that one isn’t mostly looking at background staining.”

At times during the conversation, Linda became overwhelmed and turned away from the camera, as Jason pressed on. They recalled that when Mei’s birthday came around earlier this year, they said nothing to each other, though they both assumed it was on the other’s mind.

“We do not discuss that,” Linda said.

During the call, Linda finally told her husband how she had spent that day. While he was at work, she finally returned to the old apartment and sat down on Mei’s bed surrounded by all her things. She had purchased a chocolate cupcake on the way and now picked at it as she imagined that her daughter was still at her side.

By the time she finished telling her story, Jason was welling up. Linda glanced over at him tenderly. “My husband didn’t know this,” she said. “I cannot cry every day, but that day, I think, I can cry in the room.”

Oh man...

Holy shit

So im reading through and sorta rolling my eyes at the idea of gambling on this disease with ones life but wow. Thats some negligence.

Even worse, I have a feeling that this is most likely gambling on fame, money, and a nature paper, instead of solving a disease.