The mucopolysaccharidoses (MPSs) are inherited lysosomal storage disorders caused by the absence of functional enzymes that contribute to the degradation of glycosaminoglycans (GAGs). The progressive systemic deposition of GAGs results in multi-organ system dysfunction that varies with the particular GAG deposited and the specific enzyme mutation(s) present. Cardiac involvement has been reported in all MPS syndromes and is a common and early feature, particularly for those with MPS I, II, and VI. Cardiac valve thickening, dysfunction (more severe for left-sided than for right-sided valves), and hypertrophy are commonly present; conduction abnormalities, coronary artery and other vascular involvement may also occur. Cardiac disease emerges silently and contributes significantly to early mortality. The clinical examination of individuals with MPS is often difficult due to physical and, sometimes, intellectual patient limitations. The absence of precordial murmurs does not exclude the presence of cardiac disease. Echocardiography and electrocardiography are key diagnostic techniques for evaluation of valves, ventricular dimensions and function, which are recommended on a regular basis. The optimal technique for evaluation of coronary artery involvement remains unsettled. Standard medical and surgical techniques can be modified for MPS patients, and systemic therapies such as hematopoietic stem cell transplantation and enzyme replacement therapy (ERT) may alter overall disease progression with regression of ventricular hypertrophy and maintenance of ventricular function. Cardiac valve disease is usually unresponsive or, at best, stabilized, although ERT within the first few months of life may prevent valve involvement, a fact that emphasizes the importance of early diagnosis and treatment in MPS.
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Acknowledgements The authors are grateful to Ismar Healthcare NV for their writing assistance, which was funded by BioMarin International, Novato, USA.
PR Harmatz has provided consulting support to BioMarin Pharmaceutical Inc., Novato, CA and Shire HGT, Cambridge, MA, and received research grants from BioMarin, speaker’s honorarium and travel support from BioMarin, Shire and Genzyme.
M Scarpa received unrestricted research and travel grants from BioMarin, Actelion, Genzyme and Shire.
C Kampmann received speaker’s honoraria and travel support from BioMarin, and research grants from Shire.
R Giugliani has provided consulting support and received research grants, speaker’s honorarium and travel support from BioMarin, Shire, Genzyme, Amicus and Actelion.