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Neurodevelopmental status and adaptive behavior of pediatric patients with mucopolysaccharidosis II: a longitudinal
Joseph Muenzer1, Barbara K Burton2, Hernan M Amartino3
1University of North Carolina at Chapel Hill, 101 Manning Drive CB# 7487, Medical School Wing E Room 117, Chapel Hill, NC, 27599-7487, USA. muenzer@med.unc.edu.
Insights
This study tracked cognitive and adaptive function in boys with Mucopolysaccharidosis (MPS) II over two years. Some patients experienced rapid cognitive decline, while others stabilized after an initial decrease.
Area of Science:
- Neuroscience
- Genetics
- Pediatrics
Background:
- Mucopolysaccharidosis (MPS) II is a rare X-linked lysosomal storage disease.
- Central nervous system involvement affects approximately two-thirds of patients, with some experiencing progressive cognitive impairment.
- The natural history of cognitive and adaptive function in MPS II patients is not well-defined.
Purpose of the Study:
- To evaluate the neurodevelopmental trajectories of boys with MPS II.
- To assess cognitive and adaptive function changes over a 2-year period.
- To identify potential patient subgroups based on neurodevelopmental patterns.
Main Methods:
- A 2-year, prospective, observational study.
- Enrolled 55 boys with MPS II aged ≥2 and <18 years, all receiving intravenous idursulfase.
- Assessed cognitive function using DAS-II GCA and adaptive behavior using VABS-II ABC scores.
Main Results:
- Baseline scores indicated low cognitive function and moderately low adaptive behavior.
- Over 24 months, modest deteriorations were observed in DAS-II GCA (-3.8) and VABS-II ABC (-2.0) scores.
- Four potential patient subgroups emerged based on cognitive decline patterns; younger patients and those with lower baseline GCA scores showed numerically greater declines.
Conclusions:
- Some MPS II patients exhibit rapid cognitive decline, while others stabilize after an initial decrease.
- These findings support further subgroup analyses to understand factors influencing cognitive and adaptive function in MPS II.
- Insights may aid in defining and understanding neurodevelopmental trajectories in this rare disease.
Background:
Mucopolysaccharidosis (MPS) II is a rare, X-linked lysosomal storage disease. Approximately two-thirds of patients have central nervous system involvement with some demonstrating progressive cognitive impairment (neuronopathic disease). The natural history of cognitive and adaptive function in patients with MPS II is not well-defined. This 2-year, prospective, observational study evaluated the neurodevelopmental trajectories of boys with MPS II aged ≥ 2 years and < 18 years.
Results:
Overall, 55 patients were enrolled. At baseline, mean (standard deviation [SD]) age was 5.60 (3.32) years; all patients were receiving intravenous idursulfase. Cognitive and adaptive function were assessed using the Differential Ability Scales, Second Edition (DAS-II) General Conceptual Ability (GCA) and the Vineland Adaptive Behavior Scales, Second Edition (VABS-II) Adaptive Behavior Composite (ABC) scores, respectively. Baseline mean (SD) DAS-II GCA and VABS-II ABC scores were 78.4 (19.11) and 83.7 (14.22), respectively, indicating low cognitive function and moderately low adaptive behavior. Over 24 months, modest deteriorations in mean (SD) scores were observed for DAS-II GCA (-3.8 [12.7]) and VABS-II ABC (-2.0 [8.07]). Changes in DAS-II GCA scores varied considerably, and data suggested the existence of four potential patient subgroups: (1) patients with marked early impairment and rapid subsequent decline, (2) patients with marked early impairment then stabilization, (3) patients with mild early impairment then stabilization, and (4) patients without impairment who remained stable. Subgroup analyses revealed numerically greater DAS-II GCA score reductions from baseline in patients aged < 7 years at baseline (vs. those aged ≥ 7 years) and in patients with DAS-II GCA scores ≤ 70 at baseline (vs. those with scores > 70); between-group differences were nonsignificant. No clear subgroups or patterns were identified for individual changes in VABS-II ABC scores. In total, 49 patients (89.1%) reported ≥ 1 adverse event (AE) and nine patients (16.4%) reported serious AEs.
Conclusions:
Some patients with MPS II had rapid declines in cognitive ability, whereas others remained relatively stable after an initial decline. These insights provide a basis for more detailed analyses of different patient subgroups, which may enhance the definition and understanding of factors that influence cognitive and adaptive function in MPS II.
Trial Registration:
ClinicalTrials.gov, NCT01822184. Registered retrospectively: April 2, 2013.
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