This is a multicenter, noninterventional, long-term follow-up study of patients with (Mucopolysaccharidosis IIIB) MPS IIIB who have completed a prior clinical trial involving the administration of ABO-101. This study is designed to provide LTFU in accordance with the FDA and European Medicines Agency (EMA) guidelines for patients treated with gene therapy products. The duration of the current study is 3 years for a total of up to 5 years post-treatment for these participants who rollover from a prior clinical trial of ABO-101. Participants will have a maximum of 5 annual scheduled visits with assessments as specified in the schedule of assessments.
