What is MPS VII (mucopolysaccharidosis 7): causes and symptoms

MPS VII is a rare, life-threatening lysosomal storage disorder1,2

MPS VII, also called Sly syndrome, is caused by 
mutations of the GUSB gene, which results in a 
deficiency of the β-glucuronidase enzyme.2,3

β-glucuronidase plays a key role in the breakdown of glycosaminoglycans (GAGs), previously called mucopolysaccharides. The inability to properly 
break down GAGs causes them to build up in the 
lysosomes.2,3

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Due to the variability of disease presentation, diagnosis of MPS VII can be delayed. It is important to test patients with suspected MPS VII at any age.4

MPS VII is a genetic disease inherited in an autosomal recessive manner5

people have MPS VII6

MPS VII is heterogeneous2,4

The wide spectrum of symptom severity and clinical presentation can significantly delay diagnosis.4

Neurological symptoms

Developmental delay and intellectual disability

Ophthalmological complications

Corneal clouding, heavy 
eyebrows, visual impairment, 
and photosensitivity

Ear, nose, and throat signs

Coarse facial features, increased head circumference, short neck, coarse hair, ear infections, enlarged tongue, and sensorineural hearing loss

Dental issues

Abnormal dentition with small 
and widely spaced teeth and gingival hypertrophy

Cardiovascular signs

Left ventricular hypertrophy, aortic insufficiency, mitral regurgitation, congestive cardiac failure, aortic stenosis, and thickened aortic and mitral valves

Pulmonary complications

Decreased pulmonary function, obstructive airway disease, sleep apnea, respiratory infections, and chronic bronchitis

Gastrointestinal signs

Hepatosplenomegaly, hernias, diarrhea, dysphagia, reflux, 
and colitis

Musculoskeletal issues

Dysostosis multiplex, joint pain and stiffness, short stature, joint contracture, scoliosis, kyphosis, gibbus, knock-knee, curved fingers, and restricted mobility

It is important to recognize the signs and symptoms of MPS VII. Early and accurate diagnosis and management may help to slow disease progression.4

MPS VII is a progressive disease1,2,5

Signs and symptoms of MPS VII generally become more severe.1,2,5

Hip dysplasia and worsening pulmonary function are two of the progressive symptoms commonly observed in patients with MPS VII. In some cases, people with MPS VII may develop new signs and symptoms, which may also progress.1,2,5

*Based on clinical presentation findings in multiple patients with MPS VII.2,3

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References: 1. National MPS Society. A Guide to Understanding MPS. Durham, NC: National MPS Society. https://mpssociety.org/cms/wp-content/uploads/2017/04/MPS_VII_2008.pdf. Accessed August 14, 2018. 2. Montaño AM, Lock-Hock N, Steiner RD, et al. Clinical course of sly syndrome (mucopolysaccharidosis type VII). J Med Genet. 2016;53(6):403-418. 3. Fox JE, Volpe L, Bullaro J, Kakkis ED, Sly WS. First human treatment with investigational rhGUS enzyme replacement therapy in an advanced stage MPS VII patient. Mol Genet Metab. 2015;114(2):203-208. 4. Lehman TJA, Miller N, Norquist B, Underhill L, Keutzer J. Diagnosis of the mucopolysaccharidoses. Rheumatology (Oxford). 2011;50(suppl 5):v41-v48. 5. Mucopolysaccharidosis type VII. National Institutes of Health Genetics Home Reference website. https://ghr.nlm.nih.gov/condition/mucopolysaccharidosis-type-vii. Accessed August 14, 2018. 6. Mucopolysaccharidosis type 7. Orpha.net rare diseases search website. https://www.orpha.net/consor/cgi-bin/Disease_Search.php?lng=EN&data_id=40&Disease_Disease_Search_diseaseGroup=Mucopolysaccharidosis-type-7&Disease_Disease_Search_diseaseType=Pat&Disease(s)/group%20of%20diseases=Mucopolysaccharidosis-type-7&title=Mucopolysaccharidosis-type-7&search=Disease_Search_Simple. Accessed August 14, 2018. 7. Cimaz R, Coppa GV, Koné-Paut I, et al. Joint contractures in the absence of inflammation may indicate mucopolysaccharidosis. Pediatr Rheumatol Online J. 2009;7:18.