MPS IV (Morquio Syndrome)
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Overview
MPS IV is a mucopolysaccharide disease known as Morquio syndrome. MPS IV takes its name from Dr. Morquio, a pediatrician in Montevideo, Uruguay, who in 1929 described a family of four children affected by this condition. As the same condition was also described in the same year by Dr. Brailsford from Birmingham, England, it is sometimes known as Morquio-Brailsford syndrome. MPS IV has a wide range of symptoms that vary in severity and are best managed with enzyme replacement therapy.
In 2014, Vimizin was approved by the FDA as an enzyme replacement therapy for MPS IVA. There is no treatment for MPS IVB. There is no cure for MPS IV.
With an estimated incidence of 1 in 200,000 to 300,000 individuals, MPS IV is considered one of the rarest forms of MPS in the United States.
Understanding the Cause of MPS and ML
Mucopolysaccharides are chains of sugar molecules used to build connective tissues in the body.
“muco” refers to the thick jelly-like consistency of the molecules
“poly” means many
“saccharide” is a general term for a sugar molecule
The body constantly replaces used materials and breaks them down for disposal. MPS IV patients are missing an enzyme essential to breaking down the mucopolysaccharide keratan sulfate. These materials remain stored in the body’s cells, causing progressive damage. Babies may show little sign of the disease, but as cells sustain damage, symptoms start to appear.
Understanding the Inheritance of the Disease
MPS IV is caused by a recessive gene. There is a one in four chance with every pregnancy that the child will inherit the variant gene from each carrier parent and will be affected with the disease. There is a two in three chance that unaffected brothers and sisters of children with MPS IV will be carriers.
Common Questions
How often do we see MPS IVA and MPS IVB?
MPS IV occurs only in approximately 1 in 200,000 to 300,000 live births in the U.S., and some estimates suggest there are less than 5,000 individuals in the United States currently living with an MPS IV diagnosis.
On average, 97% of MPS IV patients in the U.S. have type A. MPS IVB is extremely rare, accounting for only approximately 3% of diagnoses.
What orthopedic symptoms should we monitor?
For individuals with MPS IV, it’s important to monitor a range of orthopedic symptoms that can affect mobility and overall health. These include cervical spine instability, particularly at the atlantoaxial joint, which can pose serious neurological risks; scoliosis or curvature of the spine; hip dysplasia; genu valgum (knock knees); joint laxity; and shortened stature with abnormal bone growth. These symptoms may progress over time, so ongoing care from an experienced orthopedic team is critical to support quality of life and prevent complications.
What do we need to know about airway issues?
Airway issues are common in individuals with MPS IV and can be serious. Due to abnormal bone and cartilage development, people with MPS IV often have a small or narrowed airway, enlarged tonsils and adenoids, and tracheal or bronchial narrowing. These changes can make breathing difficult, especially during sleep or when under anesthesia. Regular airway evaluations, including sleep studies and imaging, are important, and care from specialists familiar with MPS is essential to manage risks and support respiratory health.
Clinical Trials
Clinical trials are research studies that determine whether treatments or devices are safe for humans. These studies also look for effective medical approaches for specific conditions and help provide reliable data for patients, researchers and doctors. Clinical trials are conducted on small groups to determine whether a drug or procedure causes negative reactions or unsatisfactory side effects.
ERT
Enzyme replacement therapy (ERT) uses an intravenous solution (IV) to replace a deficient or missing enzyme in the body. ERT does not cure the disease but slows its progress by increasing the amount of missing enzyme in the body.
Vimizim™ (elosulfase alfa), developed by BioMarin Pharmaceutical Inc. is the enzyme replacement therapy for individuals with MPS IVA (Morquio A syndrome.) Vimizim is administered weekly via intravenous infusion. BioMarin will offer support to patients through its BioMarin Patient & Physician Support (BPPS) team. Through BPPS, patients receive live, personalized support by a specialized case manager who will research insurance coverage and alternative benefit options. BPPS will help patients obtain coverage and minimize out-of-pocket expenses and find alternative financial assistance for treatment.
To reach a BPPS case manager, please call 866-906-6100. For more information about VIMIZIM, please visit www.VIMIZIM.com.
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