The study will evaluate safety and efficacy of intrathecal delivery of GC101 gene therapy drug as a treatment of spinal muscular atrophy Type 3 (SMA 3) patients.
≥2 years of age on the day of signing the informed consent form;
Genetic and clinical diagnosis of type 3 SMA with bi-allelic deletion of SMN1 of 5qSMA;
Hammersmith Functional Motor Scale - Expanded (HFMSE) score is between 10 and 54 at screening;
Female patients of childbearing age who are pregnant or lactating, as well as all enrolled patients （both male and female), should take effective contraceptive measures within 6 months after the treatment;
Patient who has participated in any previous gene therapy research trials;
Patient who has AAV9 neutralizing antibody titer ≥1:200;
Patient who has received Nusinersen within 120 days and Risdiplam within 15 days before treatment;
Patient who requires invasive or non-invasive ventilatory support averaging≥16 hours/day at screening;