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Charles Darwin

What is Sanfilippo syndrome?

Mucopolysaccharidosis type III (MPS III) is also known as Sanfilippo syndrome. It is a rare genetic condition, classified as a lysosomal storage disease. Lysosomes are cells with special proteins that breakdown and recycle molecules within the body. Children with Sanfilippo have genetic variations that interfere with the lysosomes. It results in little to no production of an enzyme within the body that normally breaks down heparan sulfate (a complex sugar molecule). The heparan sulfate accumulates and damages the cells within the child's body, especially within the central nervous system. There are four enzymes responsible for breaking down heparan sulfate. Sanfilippo is separated into four subtypes, differentiated by the affected enzyme. Sanfilippo is an autosomal recessive disorder, which means that the child must receive a defective copy of the gene responsible for enzyme production from each parent. MPS III affects approximately 1 in 70,000 births with MPS IIIA and MPS IIIB more common than MPS IIIC and MPS IIID. Sanfilippo syndrome was identified in 1963 by Dr. Sylvester Sanfilippo.


Declan has Sanfililppo B, which affects 1 in 200,000 children. He was diagnosed at the age of 4, in 2018. Declan will continue to regress, eventually losing his ability to walk and feed himself. He will have hearing loss and vision impairment, seizures, and then pass away. It is a devastating disease that takes everything.

It takes who your child was and who they were meant to be.

chart of Sanfilippo progression

What are the signs and symptoms of Sanfilippo?

Symptoms typically begin after the first year. Early symptoms include recurrent ear infections/sinus infections, frequent diarrhea, delayed speech, intellectual disabilities, aspects associated with autism (such as communication issues or socialization), behavioral problems, trouble sleeping, and hyperactivity. As the disease progresses, children develop movement disorders, seizures, hearing loss, vision loss, arthritis or stiff joints, worsening mental status, and the inability to walk, talk, or self-feed. Children may also have coarse facial features such as thick eyebrows and hair.

How is Sanfilippo syndrome diagnosed?

Children with Sanfilippo are often initially diagnosed with a developmental delay or Autism. Sanfilippo can go undiagnosed for years. The most common initial test is a urine screening. High levels of glucosaminoglycans (GAGs) can confirm a diagnosis. GAGs are also known as mucopolysaccharides, i.e. heparan sulfate. False negatives can occur so a genetic panel test, using blood, a cheek swab, or saliva, is suggested for lysosomal storage diseases, available through Invitae. Their screening analyzes 53 genes associated with 20 different lysosomal storage diseases. A final confirmation is done using a blood enzyme panel. This is the most credible diagnostic because it can detect whether or not one of the enzymes required to break down heparan sulfate is minimal or missing. This is the functional cause of Sanfilippo. Carrier testing is also available for those with a family history of Sanfilippo.

How is Sanfilippo syndrome treated?

There is currently no FDA-approved treatment or cure available for Sanfilippo. Present management includes therapies and/or palliative care. This is why we need your help. Research to find the first ever treatment or cure for Sanfilippo is underway, and many of these projects are funded by the Cure Sanfilippo Foundation (CureSFF). Therapeutic avenues include clinical trials investigating strategies like enzyme replacement therapy and gene therapy. Pre-clinical scientific projects require funding and your donations directly support these avenues of research. Learn more about the projects that CureSFF is a part of at the foundation's website, located here.

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