May also be called: Sanfilippo's Syndrome; Mucopolysaccharidosis Type III; MPS III

Sanfilippo (san-fuh-LEE-po) syndrome is a genetic disorder that makes the body unable to break down certain carbohydrates (sugars) in the blood, leading to serious problems in the brain and nervous system.

More to Know

The body produces substances called glycosaminoglycans (GAGs) to help build cartilage and do other important functions. GAGs, also called mucopolysaccharides, are long chains of sugar molecules that the body needs to help it develop correctly. Once GAGs have done their job, the body breaks them down through metabolism.

When a child is born with Sanfilippo syndrome, it means that he or she has a defect in the genes that make enzymes needed to break down a GAG called heparan sulfate. Over time, the used heparan sulfate builds up in the cells and keeps them from working the way they should. This can damage organs and lead to severe problems with growth, mental development, and behavior.

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

A family history increases the risk for Sanfilippo syndrome, which affects about 1 in 70,000 births. Symptoms usually appear gradually when a child is between 2 and 6 years old, and get worse over time. Most kids with Sanfilippo syndrome reach their teenage years, and some can live longer, although others with severe types of the condition may die younger.

Keep in Mind

At this time, there is no cure for Sanfilippo syndrome, although some tests and clinical trials have many doctors believing that help could be on the way. Treatment for Sanfilippo syndrome is focused on easing symptoms and giving a child the best quality of life for as long as possible.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.