Gene therapy reverses fragile X symptoms in mouse models

A preclinical study using adeno‑associated viral (AAV) vectors to deliver a functional human FMR1 gene restored the missing fragile X mental retardation protein (FMRP) in key brain regions of Fmr1‑knockout mice. The treatment reduced susceptibility to fatal audiogenic seizures, lowered sensory hyperactivity, decreased repetitive digging behavior, and normalized the elevated low‑gamma EEG power that serves as a biomarker in human fragile X syndrome.

The researchers demonstrated efficacy when the therapy was administered at developmental stages corresponding to ages 4‑6 and 15‑30 years in humans, suggesting that therapeutic benefits may be achievable beyond early childhood. Two delivery routes—intracerebroventricular and intravenous—were explored to achieve broad brain coverage. While the results provide a translational foundation for future human trials, the approach has not yet been tested in patients.