About Sanfilippo

What is Sanfilippo Syndrome, and what causes it?

"It's difficult to explain to strangers why your 6 year old’s little sister is surpassing him in development..."

Tim & Valerie Byers, parents of Will

Imagine Alzheimer’s, but in children.

In a nutshell, that’s what every family of children with Sanfilippo faces. Our children are born with a genetic defect passed on from each parent that results in their body being unable to break down and recycle natural cellular waste due to a missing enzyme. Because the waste isn’t broken down, it builds up in their brains, taking away all their skills and knowledge until they pass away in their early teens.

These videos help explain what Sanfilippo is, from the points
of view of families living with it and a doctor working to cure it:

Saving Eliza

This is the story of Eliza O’Neill and her family… But it’s a story similar to the one all Sanfilippo families have experienced.

Our MPS Journey: The Jussop Family

The story of the Jessop family, which documents the Sanfilippo journey of their oldest son, Dylan.

60 Minutes Interview

Professor John Hopwood, one of the doctors working to cure Sanfilippo syndrome, explains the disease in this 60 Minutes interview.

Learn More About Sanfilippo:

What causes sanfilippo?

Sanfilippo Syndrome (also known as MPS III) is a progressive and fatal disease affecting 1 in 70,000 children. It is a genetic condition that affects the metabolism and results in severe damages to the Central Nervous System (CNS).

Individuals affected by Sanfilippo lack an enzyme necessary to break down long chains of sugar molecules called mucopolysaccharides (also known as glycosaminoglycans or GAGs). As these molecules accumulate in the cells, they start causing cellular dysfunctions, particularly in the brain.

Sanfilippo is part of the MPS group of diseases.

MPS (Mucopolysaccharidosis) diseases fall under the Lysosomal Storage Disorders (LSDs). The lysosome is a very small unit in the cell and contains enzymes responsible for recycling cellular materials. A Lysosomal Storage Disorder is a disease where those materials don’t get recycled correctly and accumulate in the cell, causing dysfunction.

Mucopolysaccharides (MPS) are complex sugar molecules also known as GAGs (GlycoAminoGlycans) naturally produced by the body and used in the building of bones, cartilage, skin, and tissues. As the body continuously produces these molecules, it needs to constantly recycle them.

Children with Sanfilippo Syndrome lack an enzyme required to recycle the heparan sulfate, one of the many complex sugar molecules (the GAGs) the body needs, resulting in extra storage of these molecules in the cells. Each enzyme is coded in a specific gene: an error on that gene results in the deficient production of that enzyme.

There are four Types of Sanfilippo: Type A, B, C and D.

Each Sanfilippo type corresponds to a particular enzyme that is missing; all these enzymes are required to break down the heparansulfate. Type A is the most common type and is also considered the most severe, although there is great variation in the disease progression within each type.

Sanfilippo is an autosomal recessive genetic condition.

Genetic means it is inherited: children get the defective gene from both their parents who carry this genetic error as a result of a genetic mutation. Both parents must be carriers for the condition to occur with 1 chance out of 4 to inherit the disease.

Recessive means the genetic error sits on a non-dominant gene; we have two copies of each gene, so carriers of a recessive gene who have a healthy copy are unaffected. There is no way of knowing if a parent is a carrier unless there is a previous history of MPSIII in the family and genetic diagnostic is undertaken.

Autosomal means the affected gene is located on a non-sex chromosome (of the 23 pairs of chromosomes we have, 22 are autosomal). Both men and women can carry the mutated gene and boys and girls can get the disease. The genes responsible for the enzyme deficiencies in MPSIII are located on chromosome 17.

Sanfilippo is a metabolic and neuro-degenerative progressive disorder.

Metabolism is the set of life-sustaining chemical transformations within the cells. These transformations are done through the actions of enzymes which act as catalysts; the missing enzyme in Sanfilippo results in a metabolic disorder.

What are the symptoms?

Children at birth appear healthy and showing no signs of the disease, although it is present.

Early symptoms:
  • Speech delay
  • Recurrent ear/sinus infections
  • Large head size
  • Diarrhea/chronic loose stool
  • Poor sleep
  • Speech/developmental delays
  • “Autistic” behaviors
  • Hyperactivity

The disease is often diagnosed when parents find their child missing development milestones, around ages 2 to 6, and undertake formal assessment. Because of its rarity, the disease remains largely unknown for most medical practitioners and it may take several years before a correct diagnostic is made. It is often misdiagnosed as autism. It is not uncommon for families to have more than one child affected before finding out they have the disease.

As the disease progresses, children will typically develop extreme activity and behavioral problems, and gradually lose all the abilities and skills they had acquired, such as speaking, walking, and eating.

Later features:
  • Progressive intellectual disability
  • Seizures
  • Enlarged liver/spleen
  • Prominent/thick eyebrows
  • Hearing loss (may occur earlier)
  • Loss of mobility
  • Loss of ability to eat by mouth

What is the prognosis?

This disorder affects primarily the Central Nervous System (CNS), resulting in brain damage. Children experience hyperactivity, sleeplessness, loss of speech and other bodily function, mental retardation, cardiac issues, seizures, loss of mobility, dementia and finally death.

The disease progression path and speed vary significantly from one child to the next, making it particularly difficult to predict. The disease symptoms cover a wide spectrum and some children may experience some of them but not others.

One of our families created this video, which documents their son’s journey living with Sanfilippo.

The disease does not yet have a cure.

And unfortunately, only limited palliative treatment currently exists; life expectancy is around 15 years. Medical research has recently achieved promising break-throughs with real hopes for the future, but we are not there yet.

What should you do if you think your child has Sanfilippo?

First: contact your child’s doctor

If you think your child might have Sanfilippo Syndrome, immediately contact your pediatrician and request a “Urine MPS screening” (a non-sterile urine specimen).

Because Sanfilippo is a rare disease, your pediatrician or family doctor may not have ever heard of it. You, like every parent, are your child’s best advocate, so don’t be deterred from asking for the test. You have a right to get an answer to your question.

Second: contact us, we’re here

We are a community, a family of Sanfilippo families. We’ll tell you all about Sanfilippo, where the research is, where things stand, and how to start raising awareness. And most importantly, we’ll support you. So please do not hesitate to contact us.

Cure Sanfilippo Foundation

501c3 non-profit
(Tax ID: 46-4322131)


P.O. Box 6901
Columbia, SC 29260