How Is Mucopolysaccharidoses Treated?

Mucopolysaccharidoses (MPS) are a group of rare genetic disorders that affect the body's ability to break down a particular type of sugar. These sugars are called glycosaminoglycans. When they build up in the body, it may cause severe physical and mental symptoms over time.^1-3

People with these conditions are short for their age. They have bone and joint problems and a range of other complications. Most cases are diagnosed after the first year of a baby's life.²

Types of MPS

Scientists have named 9 types and several subtypes of mucopolysaccharidoses, including:^2-4

• MPS I-H (MPS 1-H): Hurler syndrome
• MPS I-S (MPS 1-S): Scheie syndrome
• MPS I H/S (MPS 1 H/S): Hurler-Scheie syndrome
• MPS II (MPS 2): Hunter syndrome
• MPS IIIA, IIIB, IIIC, and IIID (MPS 3A, 3B, 3C, and 3D): Sanfilippo 3A, 3B, 3C, and 3D syndromes
• MPS IVA and IVB: Morquio 4A and 4B syndromes
• MPS V (MPS 5): former category for Scheie syndrome
• MPS VI (MPS 6): Maroteaux-Lamy syndrome
• MPS VII (MPS 7): Sly syndrome
• MPS VIII (MPS 8): no longer a recognized syndrome
• MPS IX (MPS 9): hyaluronidase deficiency

Symptoms can be mild to severe, depending on the type of MPS. Even within the same family, people with the same type of MPS can have different symptoms and levels of severity. Mild forms may not become obvious until the teen years.³

People with Scheie syndrome have the mildest form of the disease. While symptoms usually become noticeable around age 5, they have normal intelligence, height, and life span. Similarly, people with a mild form of Hunter syndrome may live into their 50s or beyond.³

Treatments for mucopolysaccharidoses

There is no cure for any type of MPS, but there are treatments that may help improve quality of life and manage the complications. These treatments do not change the course of the disease and are not available for all types of MPS.^3,5

Type 1s – Hurler, Hurler-Scheie, and Scheie syndromes

The enzyme replacement therapy laronidase (Aldurazyme®) is approved to treat people with the Hurler and Hurler-Scheie forms of MPS 1. It is also approved for people with moderate-to-severe symptoms of the Scheie form. Some children under age 2 with MPS 1-H may benefit from a bone marrow transplant.⁵

Type 2 – Hunter syndrome

The enzyme replacement therapy idursulfase (Elaprase®) is approved to treat people with MPS 2, which is also called Hunter syndrome.⁵

Type 4 – Morquio syndrome

The enzyme replacement therapy elosulfase alfa (Vimizim®) is approved to treat people with MPS 4A. It is not approved for MPS 4B.^5,6

Type 6 – Maroteaux-Lamy syndrome

The enzyme replacement therapy galsulfase (Naglazyme®) is approved to treat people with Maroteaux-Lamy syndrome. Studies show it improves the ability to walk and climb stairs.^5,7

Type 7 – Sly syndrome

The enzyme replacement therapy vestronidase alfa-vjbk (Mepsevii™) is approved for people with MPS 7, which is also called Sly 7 syndrome.⁵

There are no approved drug treatments for MPS types 3, 4B, and 9.^5,6,8

Other treatments

A variety of other treatments may be used to address the many symptoms and complications of MPS. These include:^2,3,5,9,10

• Surgery and growth guides to correct bone alignment
• Surgery to remove the tonsils and adenoids to improve breathing
• Neck surgery to help with instability and underdevelopment
• Back surgery to correct rounding of the back
• Heart valve replacement
• Prescriptions to combat infections

Physical therapy and exercise may help improve joint stiffness. Surgery may be needed to drain fluid off the brain. People with MPS may also have a wide range of complications, such as:^3,9

• Heart disease
• Eye problems
• Hearing problems
• Carpal tunnel syndrome
• Hernias

Research for new MPS treatments

Gene therapy studies are underway for some types of MPS. Each of the 9 different types of MPS is caused by a different faulty gene. The hope is that gene therapy may be able to slow the progression of MPS, though it will not be able to reverse any damage that has already occurred.¹

Gene therapy works by introducing a working version of a gene into the body. The idea is that the body can then create the enzyme it needs, which will help decrease the buildup of glycosaminoglycans. If it works, this treatment could be a one-time procedure.¹

If you are interested in learning more about clinical studies into new treatments for MPS, talk to your doctor or visit ClinicalTrials.gov.