In a phase I-II clinical trial, 3 patients with late-infantile MLD (2 presymptomatic and 1 early-symptomatic) and 1 early-juvenile early-symptomatic patient, aged 9 months to 5 years, were treated with this vector.35 AAVrh10-hARSA was detected in urine, and significant increase in ASA activity was observed in the CSF. This evidence concerns the gene ARSA and metachromatic leukodystrophy.