Sanfilippo Syndrome and Autism

Many children with Sanfilippo Syndrome are first diagnosed with autism.

Often the parents feel the autism diagnosis “doesn’t quite fit” and they continue pursuing answers. It is then that the underlying cause of Sanfilippo is discovered.

There are questions and confusion about the interplay of Sanfilippo and autism. The following is information about the two conditions and how they intersect.

Is autism a symptom of Sanfilippo?

Sanfilippo is one of the many genetic disorders that can be an underlying cause of autism. It is common for people with Sanfilippo to have both a diagnosis of Sanfilippo syndrome and autism.

To determine if your child also has autism, they will need formal testing by a child psychologist using a validated autism test
(i.e., ADOS, CARS).

The importance of discovering the “why” behind autism diagnosis

Children who meet diagnostic criteria for autism, may be able to access additional therapies that could be helpful. For example, families of children with Sanfilippo have found behavioral therapies such as ABA (applied behavioral analysis) to be very helpful in improving challenging behaviors and as techniques for learning.

Typically, a formal autism diagnosis is also required for insurance to consider covering behavioral therapy.

If your child is diagnosed with autism and you want further answers, you are within your rights to request a complete medical workup from your child’s primary care provider.

Is autism a misdiagnosis of Sanfilippo?

In Sanfilippo, we say that autism is a co-occurring diagnosis.

Sanfilippo is the underlying cause for autism in children with this genetic abnormality. A diagnosis of Sanfilippo does not take away the autism diagnosis.

If a child is diagnosed with autism, but the underlying cause of Sanfilippo is not recognized, this is considered to be a “incomplete” diagnosis.

In the past, literature has described austim in children with Sanfilippo as a misdiagnosis. Denying a child with Sanfilippo a diagnosis of autism, assuming the child does meet diagnostic criteria, is harmful because so many of these children benefit from appropriately-delivered and patient-centric ABA therapy.

Cara O'Neill, MD, FAAP

Chief Science Officer, Cure Sanfilippo Foundation

Why is having both diagnoses important?

It benefits patients and families in the Sanfilippo community to embrace the autism diagnosis. It provides a larger community to draw learnings from and awareness, access to helpful therapies such as ABA, and resources that otherwise Sanfilippo patients would find it very hard to access or be approved by insurance.

Do all lysosomal storage disorders co-occur with autism?

A research project co-funded by Cure Sanfilippo Foundation and Sanfilippo Children’s Foundation (Australia) recently published its findings, “Altered heparan sulfate metabolism during development triggers dopamine-dependent autistic-behaviours in models of lysosomal storage disorders,” in the June 2021 edition of Nature Communications.

The work sheds light on a critical, but historically-understudied area – mechanisms behind the autism-related behaviors common in Sanfilippo. It is a new and interesting line of research that looks deeply at the mechanisms behind the behaviors of children with Sanfilippo. It also considers what types of drugs might be used to help not only treat the symptoms, but might preserve the neurological pathways in the dopamine system.

The Foundation is not aware of other studies that have proposed lysosomal dysfunction as a causative reason for non-syndromic autism. However, there is a great amount of new science emerging and many connections are coming to light among diseases that weren’t thought of years ago.

It is likely that there are many pathways or disruptions in the brain that lead to the symptoms of autism.

How does thinking about autism help find a cure for Sanfilippo?

In the clinical trial of anakinra, funded and brought together by Cure Sanfilippo, an outcome measure designed for autism is being used as a clinical endpoint because the questions capture a wide range of the neurobehavioral symptoms in Sanfilippo (sleep, agitation, stooling, engagement, etc.).

Are children with Sanfilippo a part of the autism community?

Yes. Many families find comfort in taking part in the autism community. The autism community being larger in population gives families more opportunities locally to connect to others and participate in events.