Autism Symptoms May Be Indicative of Sanfilippo Syndrome, Data Review Finds

Sanfilippo syndrome patients show symptoms of autism spectrum disorder (ASD), specifically in the areas of speech, language, and communication, which can lead to misdiagnosis or late diagnosis, a data review shows.

The review, “Symptoms of Autism Spectrum Disorder (ASD) in Individuals with Mucopolysaccharide Disease Type III (Sanfilippo Syndrome): A Systematic Review,” was published in the Journal of Autism and Developmental Disorders.

The results suggest the need for a closer and more careful analysis of patients’ symptoms by clinicians, who should consider testing for Sanfilippo syndrome when these ASD-related symptoms occur alongside other developmental problems.

Sanfilippo syndrome, also called mucopolysaccharidosis type III (MPS III), is a rare genetic disease that causes toxic accumulation of heparan sulfate, a large sugar molecule, resulting in progressive damage.

While every cell in the body is affected, cells from the central nervous system, or the brain and spinal cord, are the most severely affected. The first signs of the disease often appear between 2 and 6 years of age, and include altered behavior, extreme hyperactivity, speech problems, developmental delays, and sleep disorders.

Many children with Sanfilippo show symptoms similar to ones of autism spectrum disorder, such as language delay and impaired social communication. This disorder affects social interaction and communication, and can limit interests or activities, and repetitive behavior.

As a result, many children are misdiagnosed with autism spectrum disorder and/or receive a late diagnosis of Sanfilippo syndrome. This increases the risk of unnecessary interventions and treatments, and delays or prevents genetic counseling and proper therapy. However, the global prevalence of ASD in Sanfilippo syndrome patients remains unknown.

Researchers performed a systematic review of data regarding symptoms consistent with ASD in individuals with Sanfilippo, using five databases. They narrowed down their search to 16 studies, involving 620 patients diagnosed with Sanfilippo syndrome.

The ASD-related behaviors and symptoms described in the studies were divided into speech, language and communication difficulties; repetitive and restricted behaviors; and social difficulties.

All studies consistently reported issues in Sanfilippo patients with speech, language, and communication, which mostly appeared after 18 months of age. Repetitive and restricted behavior was the least reported ASD-related symptom.

Results suggested that the profile of autism spectrum disorder in Sanfilippo patients consists of speech, language, communication, and social difficulties, with little evidence of repetitive or restricted behavior.

Initial misdiagnosis, as well as late diagnosis, were reported in almost half of the studies. Misdiagnoses included autism spectrum disorder, attention deficit hyperactivity disorder, acquired language disorder, and intellectual disability.

When speech, language, and communication problems “occur alongside other physical or developmental abnormalities, clinicians should consider screening for MPS III to allow for early identification and diagnosis,” the team said.

The authors also noted the review’s limitations, including the fact that many of the studies were small and lacked details regarding symptoms and behaviors characteristic of autism spectrum disorder.

Future research should include a more detailed analysis of ASD symptoms in Sanfilippo syndrome to better understand the link between these two disorders.