Efficacy METAZYM for the Treatment Metachromatic Leukodystrophy Treated With Hematopoietic Stem Cell Transplantation

Inclusion Criteria: * Subject's legally authorized guardian(s) must provide signed, informed consent prior to performing any study-related activities. * The patient must have a confirmed diagnosis of MLD as defined by:ARSA activity \< 10 nmol/h/mg in leukocytes prior to HCT; Presence of elevated sulfatide in urine prior to HCT * The patient must have a residual level of voluntary function (as judged by the investigator), including presence of residual cognitive function (attention, executive and visual functions) as well as the presence of residual voluntary motor function in one upper or lower limb as a minimum. * The patient must have an age at the time of screening ≥ 6 months * The patient must have had onset of symptoms before the age of 4 years * The subject and his/her guardian(s) must have the ability to comply with the clinical protocol * The patients' medical record must document that the legal guardian(s) has had independent counselling or a consultation regarding stem cell transplantation in order to assure that the guardian(s) is fully informed regarding the risks and benefits of this alternative Exclusion Criteria: Patient will be excluded from this study if they do not meet the specific inclusion criteria, or if any of the following criteria apply: * Presence of a gross motor function measure (GMFM \< 25) * Presence of severe pseudo-bulbar signs (weakness and disco-ordination of tongue and swallowing muscles leading to severe difficulty with swallowing) * Sp…