Rare Classroom: Maroteaux-Lamy Syndrome

Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The disease that we will be learning about today is:

Maroteaux-Lamy Syndrome

This disease is also known as mucopolysaccharidosis VI (MPS VI).

What is Maroteaux-Lamy Syndrome?

  • A lysosomal storage disorder
  • Cell compartments (lysosomes) fill up with a sugar ​molecule called glycosaminoglycan (GAG)​
  • MPS VI is caused by the buildup of GAG in lysosomes in ​organs and tissues throughout the body ​
  • MPS VI is an inherited disease
  • It affects the lungs, heart, bones, eyes and other organs 
  • The symptoms can be mild or life-threatening
  • MPS VI is a rare disease; it happens in only about 1 out of every 340,000 live births
  • An estimated 1,100 people worldwide are living with MPS VI
  • People with MPS VI generally do not display any features of the condition at birth. 
  • They often begin to show signs and symptoms during early childhood.
  • MPS VI affects males and females equally

How Do You Get It?

  • MPS VI is caused by an inherited genetic change that causes a person to be deficient in the enzyme arylsulfatase B(ASB)
  • Genes carry the instructions for traits like eye color and hair color as well as a multitude of instructions that our body needs to function properly, including instructions to make ASB and all other enzymes
  • Genes are inherited in pairs (one copy from each parent)
  • People who have one working ASB gene and one nonworking gene are called carriers; they make enough ASB to remain health and do not have MPS VI. 
  • Individuals who have MPS VI, have inherited 2 nonworking copies of the ASB gene-one from each parent 

What Are The Symptoms?

  • The buildup of GAG leads to airway blockages and other symptoms in the ears, nose and throat
    • Narrowed nostrils due to flattened nasal bridge
    • Buildup in the soft tissues (enlarged tonsils, tongue, and other areas of the neck & throat)
    • Excess production of thick mucus
    • Airway blockages can cause many other problems
  • Ears
    • Repeat ear infections 
    • Hearing loss is common
  • Nose
    • Flattened nasal bridge
    • Persistent thick mucus
    • Persistent stuffy nose and infections
  • Throat
    • Narrowed airway
    • Enlarged tongue and lips
  • Heart and Circulation
    • Heart-related problems are very common in MPS VI
    • Symptoms worsen with age, even in patients with slowly progressing MPS VI
    • Caused by GAG buildup in heart 
      • Heart valve disease
      • Blockages in the arteries (large blood vessels)
      • High blood pressure 
  • Bones and Joints
    • Differences in the bones and joints are often the first visible signs of MPS VI
    • GAG buildup affects bone growth, skeletal development, and joint function​
    • Short stature/slow growth
    • Curved spine
    • Rib cage changes
    • Joint problems
    • Abnormal gait (walking issues)
    • Large head
    • Pronounced forehead
    • Flattened nasal bridge 
  • Eyes and Vision
    • Eye disease often affects MPS VI patients
      • 40 percent have vision impairment
    • Caused by GAG buildup in the eye itself and in related nerves 
    • Clouding of the cornea(clear outer eye layer)
    • Vision difficulties 
    • Optic Nerve abnormalities 
    • Eye pressure and glaucoma 
  • Lung and Breathing
    • Lung function is often affected by MPS VI
    • MPS VI lung disease takes two forms:
      • Obstructive
      • Restrictive
    • This issues can be potentially lethal and are a major concern during surgeries and anesthesia
    • Narrowed or blocked airways (throat and lungs​)
    • Breathing difficulties 
    • Chest shape abnormalities 
    • Repeat lung infections (including pneumonia)
  • Brain and Nerves
    • GAG builds up in brain cells 
    • GAG can cause narrowing of nerve pathways in the spine, limbs, and elsewhere
    • MPS VI does not directly affect a person’s ability to think or learn
    • Increased pressure on the brain 
    • Carpal tunnel syndrome (pinching of nerves in the wrist, causing pain or numbness
    • Compression (pinching of the spinal cord in the neck and back)

How Is It Treated?

  • Naglazyme®
  • First and only enzyme replacement therapy for the treatment of mucopolysaccharidosis (MPS VI), an inherited life-threatening lysosomal storage disorder 
  • Received FDA approval in May 2005
  • Approved in the US , European Union and at least 7 other countries in the rest of the world for the treatment of MPS VI
  • Designated an orphan drug in the US and internationally 
  • On Fierce Pharmas list of most expensive drugs in the world with an annual patient cost of $485,747
  • Works as an enzyme replacement therapy (ERT) for diseases that are caused by an enzyme that the body cannot make sufficiently.
  • ERT replaces the missing enzyme with a substitute enzyme 
  • Naglazyme® is a highly purified protein, identical to the natural enzyme that is missing in patients with MPS VI
  • Treatment is administered by IV infusion 
  • In clinical studies, Naglazyme® has been shown to help MPS VI patients with endurance.  
  • In timed tests, people who took Naglazyme® were able to climb more stairs and walk farther than before

Where Can I Learn More???

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