Diagnosing MPS VI
Diagnosis of MPS VI is usually prompted through clinical presentation.1 Elevated urinary glycosaminoglycan levels suggest a mucopolysaccharidosis disorder.1 MPS VI is diagnosed by testing arylsulfatase B (ASB) activity in blood or fibroblasts. MPS VI is confirmed when ASB enzyme activity in the leukocytes or fibroblasts is determined to be low as judged against a reference enzyme and the laboratory’s own reference ranges.2
When to suspect MPS VI
Because patients with MPS VI present with a variety of signs and symptoms, it is essential to maintain a high index of suspicion and pay close attention to the medical history.3 Suspicious signs and symptom clusters may include3:
- Macrocephaly
- Dysmorphic facial features
- Short stature
- Enlarged tongue
- Enlarged tonsils and adenoids
- Corneal clouding
- Impaired vision
- Short neck
- Difficulty swallowing
- Noisy breathing
- Umbilical or inguinal hernias
- Sinopulmonary infections
- Heart murmur
- Valve disease
Refer promptly
Once a clinical suspicion has been raised, all patients with suspected MPS VI should be referred promptly to a geneticist for definitive diagnosis and appropriate counseling.4
Benefits of early diagnosis
When MPS VI is recognized promptly and patients are carefully managed, its harmful effects may be minimized. That’s because early diagnosis of MPS VI can allow for early treatment that optimizes the potential benefits of enzyme replacement therapy with NAGLAZYME® (galsulfase).5 In clinical trials, NAGLAZYME has been shown to improve walking and stair‐climbing.6 This improvement can be maintained with long‐term therapy. A study that measured the 6‐minute walk test in patients with MPS VI, many of whom had been on NAGLAZYME therapy for a long time (an average of 6.8 years), showed that improvements in endurance lasted when patients kept taking NAGLAZYME.7
Learn more about the long-term efficacy of NAGLAZYME »
The dangers of delayed diagnosis
Both the slowly and rapidly progressing forms of MPS VI result in significant declines in physical functioning and well-being, as well as a shortened lifespan.1 A 2018 literature review found the median delay in diagnosis for patients with MPS VI was 4.7 years.8
Once multisystemic damage occurs, it cannot be reversed. Treatment, however, may help to restore endurance and slow the rate of disease progression.5,6
Growth and skeletal abnormalities are common in undiagnosed MPS VI
- Accelerated growth in infancy coupled with advanced bone maturation is often followed by slowing growth in the first few years of life and short stature9
- Final height may range from extreme to mild short stature9
- MPS disorders have a common radiological expression known as dysostosis multiplex that involves almost all of the bony skeleton10
Cardiac abnormalities: also common in MPS VI1
Cardiac disorders are common in MPS VI and a frequent cause of morbidity and mortality.
- Cardiac disorders most commonly manifest as progressive valve degeneration with stenosis or insufficiency
- Other manifestations include:
- Electrocardiographic abnormalities
- Systemic vascular narrowing and hypertension
- Endocarditis
Learn more about caring for patients with MPS VI »