I'm honestly quite shocked that the physicians/scientists involved would choose to use an AAV for a brain-targeted gene therapy. There is just so much data demonstrating that these vectors are quite immunoreactive: most of the approved gene therapies based on AAVs carry black box labels for liver failure caused by an immune reaction to the viral capsid. Admittedly, AAVs are the most derisked vector for gene therapies, but infusing them directly into someone's brain and expecting nothing bad to happen is, in my view, crazy.

Another compounding issue is that they had to package the vector into two parts, which then have to both infect the same cell to get any effect. Which means you have to at least double the dose to get similar coverage compared to a single AAV vector (and actually more than double). Seems like a easy recipe for liver toxicity. Which is why most companies doing AAV therapy either target the liver or the eye (where AAV doesn't escape to the liver).

I feel like the parents were not well enough informed of the risks, and the PI rushed the therapy to be famous. Not the first time this has happened, and not the last, sadly.