ARSA and metachromatic leukodystrophy: In particular, a phase I/II multicentre open-label dose escalation study started in 2011 exploiting the intra-thecal delivery of a biological recombinant of human arylsulfatase A (HGT-1110), for a total of 38 weeks (20 injections) in children with MLD (ClinicalTrials.gov Identifier: NCT01510028).