New Delhi, July 30 -- SHANGHAI - Mei was six years old when her parents paid more than $800,000 to fund an experimental treatment they hoped might give her a chance at life. She had Snijders Blok-Campeau syndrome, a rare genetic condition caused by mutations in the CHD3 gene that disrupts brain development, and in late March 2025 a surgical team affiliated with Shanghai Jiao Tong University's School of Medicine injected hundreds of trillions of viral particles directly into her spinal fluid. The goal was to reach neurons in her brain and correct the mutations using CRISPR base editing. No human being had ever been treated this way before. She died approximately one week later, from a severe immune reaction the procedure triggered.

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