Mucopolysaccharidosis type I



What is mucopolysaccharidosis type I?

Mucopolysaccharidosis type I (MPS I) is a condition that affects many parts of the body. This disorder was once divided into three separate syndromes: Hurler syndrome (MPS I-H), Hurler-Scheie syndrome (MPS I-H/S), and Scheie syndrome (MPS I-S), listed from most to least severe. Because there is so much overlap between each of these three syndromes, MPS I is currently divided into the severe and attenuated types.

People with MPS I can’t make a specific protein called alpha-L iduronidase, which is needed to break down sugars. These sugars build up in cells and cause damage throughout the body.

People who have this disease can have problems with how their bodies grow and work, as well as trouble with thinking and learning. They might look different, too.

Many people with milder MPS I can go to school and eventually work and have families. And even for people with more severe MPS I, there are treatments to help ease their symptoms and slow down the disease.

How common is mucopolysaccharidosis type I?

Mucopolysaccharidosis type I is rare. Severe MPS I occurs in approximately 1 in 100,000 newborns. Attenuated MPS I is less common and occurs in about 1 in 500,000 newborns. Please discuss with your doctor for further information.


What are the symptoms of mucopolysaccharidosis type I?

The common symptoms of mucopolysaccharidosis type I are:

  • Enlarged head, lips, cheeks, tongue, and nose
  • Enlarged vocal cords, resulting in a deep voice
  • Frequent upper respiratory infections
  • Sleep apnea
  • Hydrocephalus
  • Hepatosplenomegaly (enlarged liver and spleen)
  • Umbilical hernia
  • Inguinal hernia
  • Hearing loss
  • Recurrent ear infections
  • Corneal clouding
  • Carpal tunnel syndrome
  • Narrowing of the spinal canal (spinal stenosis)
  • Heart valve abnormalities, which can lead to heart failure
  • Short stature
  • Joint deformities (contractures)
  • Dysostosis multiplex (generalized thickening of most long bones, particularly the ribs)
  • Developmental delays and regression

The signs and symptoms of mucopolysaccharidosis I (MPS I) are not present at birth, but they begin to appear during childhood. People with severe MPS I develop the features of this condition earlier than those with attenuated MPS I.

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.


What causes mucopolysaccharidosis type I?

MPS I is passed down through families. But you get it only when both parents give you a broken gene.

If you get one normal gene and one “bad” gene, you won’t have symptoms of MPS I. You could pass the gene to your children, though.

Risk factors

What increases my risk for mucopolysaccharidosis type I?

Please discuss with your doctor for further information.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is mucopolysaccharidosis type I diagnosed?

Because it’s a rare disease, doctors rule out other medical conditions first. Your doctor might ask:

  • What symptoms have you noticed?
  • When did you first see them?
  • Do they come and go?
  • Does anything make them better? Or worse?
  • Has anyone in your family had similar symptoms in the past?

If the doctors can’t find another explanation for your child’s symptoms, they’ll test for MPS I by checking for:

  • A lot of a specific sugar in their urine
  • How active the “missing” protein is in their blood or skin cells

After doctors are sure it’s MPS I, it’s a good idea to let your extended family know about the gene problem, too.

If you’re a woman who gets pregnant and you know you carry the gene, or you already have a child with MPS I, you can find out whether the baby you’re carrying is affected. Talk to your doctor about testing early in your pregnancy.

How is mucopolysaccharidosis type I treated?

Enzyme replacement therapy (ERT) uses a drug called laronidase (Aldurazyme), a man-made version of the missing protein. It has changed the outlook for many kids with MPS I. It can relieve most symptoms and slow the progress of the disease, although it doesn’t help treat symptoms from the brain, like problems with thinking or learning.

Another option may be a hematopoietic stem cell transplant (HSCT), in which doctors put new cells into your child’s body that might make the protein their body is missing. These cells often come from bone marrow or umbilical cord blood. When children get a transplant before they’re 2 years old, they might be able to learn better. But HSCT can’t fix bone or eye problems.

Work with a doctor who specializes in lysosomal storage diseases, or LSDs. Depending on what symptoms your child has, you might need to see other specialists, too. Often they’ll include a cardiologist, who focuses on the heart, and an eye doctor.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage mucopolysaccharidosis type I?

The following lifestyles and home remedies might help you cope with mucopolysaccharidosis type I:

  • Encourage your child to be independent and make friends. Kids with MPS I are often well-liked and enjoy being with others. Include them in safe family activities.
  • Most important, be positive. Keep an open mind about other people’s reactions when you introduce your child to them. They might not know what to say, possibly because they don’t want to pry or offend or embarrass you. When people ask about your child, tell them about his condition and what he can and can’t do. Also mention your child’s interests, his curiosity, and his personality.
  • Talk to the staff at your child’s school to come up with an individualized education program (IEP). Your child might need one-on-one attention in the classroom, a special desk, or other adjustments.
  • To protect their necks, kids with MPS I should avoid contact sports, gymnastics, trampolines, and similar activities.
  • Look for ways to change how your home is set up to make it easier for your child to move around and do things on his own.
  • Make time for yourself and your family, too. It’s OK to have someone take over caregiving duties for a while. Step back and take a break to rest and recharge.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: October 27, 2017 | Last Modified: October 27, 2017