Mucopolysaccharidosis patients have reduced functional capacity

Abstract

Introduction Mucopolysaccharidoses (MPSs) are a group of rare diseases caused by an intralysosomal accumulation of glycosaminoglycans, resulting in a multisystemic clinical condition characterized by variable degrees of physical‐functional impairment. Objective To evaluate the functional capacity (FC) of MPS patients and compare with a healthy control group. Methods This is a cross‐sectional study of 6‐ to 39‐year‐old patients followed at a medical reference center and compared with their control peers, matched by age and sex. FC was assessed using the Sit‐to‐Stand Test (SST) and Incremental Shuttle Walk Test (ISWT). Heart rate (HR) and Borg rating of perceived exertion were measured before and after ISWT. HR recovery (HRR) was defined as the HR at the end of the test minus the HR in the second minute after ISWT. Results Nineteen (19) MPS patients, 69% with type II MPS and mean age 17 ± 11 years were evaluated. Every patient was under enzyme replacement therapy. The time to perform the SST was longer in the MPS group (10.6 ± 2.5 s vs. 6.7 ± 1.2 s; p < .01). The MPS group achieved lower values of distance covered on the ISWT (407.6 ± 329.8 m vs. 1131.9 ± 183.3 m; p < .01), with a significantly higher Borg (6 [5–8] vs. 2 [1–4]; p = .02). The MPS group's HRR was slower than the controls (32.9 ± 20.2 beats per minute [bpm] vs. 69.1 ± 25.9 bpm; p < .001). Discussion We observed a pronounced reduction in the MPS group's FC compared to their healthy peers and a worse HRR after completing the test.

Current Understanding on the Genetic Basis of Key Metabolic Disorders: A Review

“…MPS II was discovered almost a century ago, and is extremely rare with an incidence of 0.38 to 1.09 per 100,000 live male births and has been linked to the X chromosome [ 86 ]. Enzyme replacement therapy (ERT) is one of the options for patients diagnosed with the phenotype [ 87 ]; however, the inability of the intravenously administered enzymes to overcome the blood brain barrier renders ERT ineffective against progressive neurodegeneration and severe symptoms in the Central Nervous System as reported in patients with neuronopathic MPS [ 88 ]. Recent advances in the development of RNA technology have led to novel approaches such as the experimental production of human iduronate-2-sulfatase (IDS) using a Sendai virus vector [ 89 ].…”