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Mol Genet Metab. 2015 Feb;114(2):170-7. doi: 10.1016/j.ymgme.2014.12.299. Epub 2014 Dec 9.

Cognitive, medical, and neuroimaging characteristics of attenuated mucopolysaccharidosis type II.

Author information

1
Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA.
2
Division of Biostatistics, University of Minnesota, Minneapolis, MN, USA.
3
Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
4
Hospital for Sick Children, Toronto, ON, Canada.
5
UCSF Benioff Children's Hospital Oakland, Oakland, CA, USA.
6
Department of Pediatrics, Oregon Health and Science University, Portland, OR, USA.
7
Department of Neurology, New York University, New York, NY, USA.
8
Department of Child and Adolescent Psychiatry, New York University, New York, NY, USA.
9
Department of Psychiatry, University of Minnesota, Minneapolis, MN, USA.
10
Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA. Electronic address: shapi004@umn.edu.

Abstract

The phenotype of attenuated mucopolysaccharidosis type II (MPS II), also called Hunter syndrome, has not been previously studied in systematic manner. In contrast to the "severe" phenotype, the "attenuated" phenotype does not present with behavioral or cognitive impairment; however, the presence of mild behavior and cognitive impairment that might impact long-term functional outcomes is unknown. Previously, significant MRI abnormalities have been found in MPS II. Recent evidence suggests white matter abnormalities in many MPS disorders.

METHODS:

As the initial cross-sectional analysis of a longitudinal study, we studied the association of brain volumes and somatic disease burden with neuropsychological outcomes, including measures of intelligence, memory, and attention in 20 patients with attenuated MPS II with a mean age of 15.8. MRI volumes were compared to 55 normal controls.

RESULTS:

While IQ and memory were average, measures of attention were one standard deviation below the average range. Corpus callosum volumes were significantly different from age-matched controls, differing by 22%. Normal age-related volume increases in white matter were not seen in MPS II patients as they were in controls. Somatic disease burden and white matter and corpus callosum volumes were significantly associated with attention deficits. Neither age at evaluation nor age at starting treatment predicted attention outcomes.

CONCLUSIONS:

Despite average intelligence, attention is compromised in attenuated MPS II. Results confirm an important role of corpus callosum and cortical white matter abnormality in MPS II as well as the somatic disease burden in contributing to attention difficulties. Awareness by the patient and caregivers with appropriate management and symptomatic support will benefit the attenuated MPS II patient.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT01870375.

KEYWORDS:

Attenuated; MRI brain volumes; Mucopolysaccharidosis type II; Neuropsychological outcomes

PMID:
25541100
PMCID:
PMC4312717
DOI:
10.1016/j.ymgme.2014.12.299
[Indexed for MEDLINE]
Free PMC Article

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