Inclusion Criteria:

• The subject must have a documented diagnosis of MLD (Groups A-F):
  • Low ASA activity in leukocytes (compared to laboratory normal range); AND
  • Elevated sulfatides in urine.
• The subject must have a gait disorder due to spastic ataxia or weakness attributable to MLD by the investigator and documented by a primary care physician or a specialist physician by 30 months of age (Groups A-C, and F), or be minimally symptomatic and ≥ 6 to < 18 months of age (Group D), or be early symptomatic and ≥ 12 to < 18 months of age (Group E).
• Subjects in Group E must have neurological symptoms documented by a primary care physician or a specialist physician.
• The subject’s age at the time of informed consent, must be:
  • Group A: 18 to 48 months of age;
  • Group B: 18 to 72 months of age;
  • Group C: 18 to 72 months of age;
  • Group D: ≥6 to <18 months of age;
  • Group E: ≥12 to <18 months of age;
  • Group F: 18 to 72 months of age.
• The subject’s GMFC-MLD level at screening must be:
  • Group A: GMFC-MLD level of 1 or 2;
  • Group B: GMFC-MLD level of 3;;
  • Group C: GMFC-MLD level of 4
  • Group D: minimally symptomatic, ≥ 6 to < 18 months of age, with the same ASA allelic constitution as an older sibling with confirmed late infantile or juvenile onset MLD;
  • Group E: early symptomatic, ≥ 12 to < 18 months of age with a GMFC-MLD level of 1 or 2, and with a history of achieving stable walking (defined as at least 1 month of independent walking);
  • Group F: GMFC-MLD level of 5 or 6 5. The subject and his/her parent/representative(s) must have the ability to comply with the clinical protocol.
• Subject's parent or legally authorized representative(s) must provide written informed consent prior to performing any study-related activities. Study-related activities are any procedures that would not have been performed during normal management of the subject.

Exclusion Criteria: 

• Multiple sulfatase disorder as determined by abnormal activity of another lysosomal sulfatase (based upon the reference laboratory’s normal range) or a known genetic disorder other than MLD.
• History of bone marrow transplant (BMT), hematopoietic stem cell transplantation (HSCT), or gene therapy or undergoes BMT, HSCT, or gene therapy at any point during the study.
• Primary presentation of MLD was behavioral or cognitive symptoms (per investigator’s clinical judgment); behavioral symptoms that are secondary to motor deficits (e.g., tantrums in response to loss of motor skills) are not exclusionary.
• The subject has any known or suspected hypersensitivity to agents used for anesthesia or has history of difficult airway or potential for airway compromise.
• Any other medical condition or serious comorbid illness that in the opinion of the investigator would preclude participation in the study.
• Subjects with laboratory, ECG, or vital sign abnormalities reflecting intercurrent illness that may compromise their safety during the trial should not be enrolled. Abnormal laboratory, vital sign and ECG results at screening should be reviewed with the Shire medical monitor.
• The subject is enrolled in another clinical study that involves use of any investigational product (drug or device) within 30 days or 5 half-lives (whichever is longer) prior to study enrollment or at any time during the study.
• The subject has had prior exposure to SHP611.
• The subject must weigh > 11 lbs (5 kg).
• The subject has a condition that is contraindicated as described in the SOPH-A-PORT Mini S IDDD Instructions for Use (IFU)