Many of us know Alzheimer’s and Dementia as a disease of the elderly, but did you know that there are actually conditions that can cause many of the same symptoms in children? One such condition is Sanfilippo syndrome. It is a rare, genetic, metabolic disorder that gets worse over time, causing fatal brain damage.
So what causes this devastating disorder? The body makes long chains of sugar molecules called glycosaminoglycans (GAG’s), also called mucopolysaccharides. They help to build cartilage (strong, flexible connective tissue that helps to protect joints and bones), connective tissue, nerve tissue and nerve tissue, helps blood to clot and are used in the communication between cells. The body continuously builds GAG’s and then once they have performed their function, the body will break them down through metabolism. One type of sugar molecule is called heparan sulfate. Children with Sanfilippo syndrome have a defect in one of the genes needed to produce the enzyme necessary to break down heparan sulfate. Without the necessary enzyme, heparan sulfate builds up in cells and prevents them from functioning as they should. This damages various organs within the body.
As there are 4 different enzymes needed to break down heparan sulfate, Sanfilippo syndrome is classified into 4 types (A, B, C, and D) depending on which enzyme is affected. Of these types, type A is the most common and the most severe, meaning that symptoms appear earlier and progress faster. As heparan sulfate is stored in a part of the cell called the lysosome, Sanfilippo syndrome is also classified as a lysosomal storage disorder. It also belongs to a group of diseases called Mucopolysaccharidoses (MPS) all of which cause GAG’s or mucopolysaccharides to accumulate. Sanfilippo is also known as MPS type 3.
Some of the symptoms of Sanfilippo syndrome include: Speech and developmental delays, many ear and sinus infections, large head size, coarse facial features (prominent forehead, full lips and nose), excessive body hair, trouble sleeping (difficulty going to sleep, frequent nighttime waking, difficulty going back to sleep), features of autism (speech regression, mouthing and oral fixation, loss of interest in social interaction, repetitive speech/behaviours), hyperactivity, impulsivity, poor sense of safety, diarrhea, enlarged liver/spleen. While kids are born with the disorder, many of the symptoms do not show until children are between the ages of 2 and 6 years old, when they may begin showing developmental delays and behavioural issues. As the disease progresses, it can lead to symptoms such as seizures, severe cognitive issues and loss of motor skills such as walking, talking and feeding.
It can take time for children to be diagnosed with Sanfilippo syndrome. The doctor may first order a urine test, to check if the levels of heparan sulfate are abnormally elevated. The doctor may then order a blood test to check if the related enzyme is missing and genetic testing to verify the diagnosis.
Sadly, there is currently no cure for Sanfilippo. However, there has been research done, mostly stem cell research as well as clinical trials using mouse and animal models. These clinical trials have investigated enzyme replacement therapy (ERT) and gene therapy. Gene and ERT therapy are currently the most promising forms of treatment, and ERT may help to stabilize the condition. These clinical trials have been effective on other forms of MPS and can help to improve the quality of life of those with Sanfilippo. However, more research in human trials is still necessary.
Sanfilippo is an awful disease, one that causes children to lose all the skills that they worked so hard to gain, and means that their families can do nothing but watch as their child slowly fades away. However, as long as there is research, there is hope. Hope that one day, when parents hear the news that their child has Sanfilippo syndrome, they are also told that it is completely treatable.
References:
Carroll, R. S. (Ed.). (2019, September). Sanfilippo syndrome (for parents) - nemours kidshealth. KidsHealth. Retrieved September 12, 2022, from https://kidshealth.org/en/parents/sanfilippo-syndrome.html#:~:text=What%20Is%20Sanfilippo%20Syndrome%3F,cure%20yet%20for%20Sanfilippo%20syndrome.
Cure Sanfilippo Foundation: To cure sanfilippo syndrome. Cure Sanfilippo Foundation | Accelerating discovery of a cure for Sanfilippo Syndrome. (2022, September 6). Retrieved September 12, 2022, from https://curesanfilippofoundation.org/
MediLexicon International. (n.d.). Sanfilippo syndrome: Cause, symptoms, and treatments. Medical News Today. Retrieved September 12, 2022, from https://www.medicalnewstoday.com/articles/sanfilippo-syndrome#treatments
Selemin, J. (n.d.). Sanfilippo syndrome: Symptoms, treatment, and diagnosis. WebMD. Retrieved September 12, 2022, from https://www.webmd.com/children/what-is-sanfilippo-syndrome#:~:text=Generally%2C%20Sanfilippo%20syndrome%20is%20easier,sulfate%20levels%20are%20too%20high.
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