Skip to main content
Go to homepage

Print Page

Sanfilippo Syndrome

What Is Sanfilippo Syndrome?

Sanfilippo (san-fuh-LEE-po) syndrome is a rare genetic metabolism disorder. A change in a single gene makes a child's body unable to break down certain carbohydrates (sugars). This leads to serious problems in the brain and nervous system.

There is no cure yet for Sanfilippo syndrome. But doctors and researchers are working hard to find better treatments for it.

What Causes Sanfilippo Syndrome?

The body makes long chains of sugar molecules called glycosaminoglycans (GAGs), also called mucopolysaccharides. They:

  • help build cartilage, connective tissue, nerve tissue, and skin
  • help blood clot
  • are used in the communication between cells

The body continually builds GAGs and, when their job is done, breaks them down through metabolism.

One type of sugar molecule is called heparan sulfate. A child born with Sanfilippo syndrome has a defect in one of the genes that make enzymes needed to break down heparan sulfate. Without the gene, the used heparan sulfate builds up in the cells and keeps them from working as they should. This can damage organs, affecting growth, mental development, and behavior.

Four enzymes are involved in breaking down heparan sulfate, so there are four types of Sanfilippo syndrome (A, B, C, and D), depending on which enzyme is affected. Type A is the most common and most severe form.

A family history increases the risk for Sanfilippo syndrome, which affects about 1 in 70,000 births. The condition is also called mucopolysaccharidosis type III (MPS III).

What Are the Signs & Symptoms of Sanfilippo Syndrome?

Kids who have the condition are born with it. But most won't have symptoms until the preschool years, when they're between 2 and 6 years old. Then, they start to show developmental delays and behavioral issues. Trouble with sleep is common.

Early signs of Sanfilippo syndrome include:

  • speech and other developmental delays
  • getting many ear infections or sinus infections
  • large head size
  • respiratory infections
  • ongoing diarrhea
  • headaches
  • sleep problems
  • behavior issues that can look like those caused by autism
  • compulsive behaviors and hyperactivity

They get worse over time, leading to:

  • seizures
  • severe cognitive problems
  • progressive loss of motor skills (walking, speaking, feeding, etc.)

Sanfilippo syndrome affects life expectancy. Most children reach their teenage years, and some can live longer.

How Is Sanfilippo Syndrome Diagnosed?

It can take time for a child to be diagnosed with Sanfilippo syndrome. Doctors might suspect it when a child has:

  • significant behavioral problems
  • speech or developmental delays that get worse over time

A urine test to check for high levels GAGs in a child's pee can help confirm a diagnosis.

How Is Sanfilippo Syndrome Treated?

There is no cure yet for Sanfilippo syndrome. Treatment focuses on easing symptoms and giving a child the best quality of life for as long as possible.

But some tests and clinical trials (for instance, with enzyme replacement therapy and gene therapy ) have many doctors believing that help could be on the way.

What Else Should I Know?

You can find support and information about Sanfilippo research online at:

Turn to your child's care team if you have questions. They're there to support your child and the whole family.

Reviewed by: Ricki S. Carroll, MD
Date Reviewed: Sep 5, 2019

Lea este articulo en Español

What next?

Summit Mall Play Area
Answer Key:
Click to expand
There are 10 nurses in the picture.

And we have many more pediatric primary care providers in Northeast Ohio. You can meet some of them here.
Summit Mall Play Area
Answer Key:
Click to expand
The five differences are:
– Phone color
– Coat pocket
– Stethoscope earpiece color
– Stethoscope bell dot
– Clipboard paper color

Need help finding a doctor, choosing a location or getting a general question about Akron Children's answered? Call us or fill out the form and we'll help in any way we can.
Summit Mall Play Area
Answer Key:
Click to expand
The two matching doctors are 9 and 14.

With virtual visits, you can see our pediatric experts from the comfort of home or wherever you are.
Summit Mall Play Area
Answer Key:
Click to expand
The correct path:
The Correct Path
We offer many ways to get pediatric care all over Northeast Ohio. Use this page to find the right kind of care and the most convenient location for you.