7 Common Symptoms of Sanfilippo Syndrome

Brian Murphy, Ph.D. avatar

by Brian Murphy, Ph.D. |

Share this article:

Share article via email
Hep C study

The symptoms of Sanfilippo syndrome can vary from child to child, and depend on the disease subtype. They can also change as the disease progresses.

Here are the seven most common signs and symptoms of Sanfilippo syndrome.

Developmental delays

One of the most common and initial symptoms of Sanfilippo syndrome is developmental delays, especially speech delays. Children usually begin normal development after their birth, but progress in intellectual, motor and speech milestones starts to slow around age 2. These children continue to fall behind throughout the preschool years.

A study in 60 children with Sanfilippo syndrome types A through C  found that 85% of them had speech delays, which usually became apparent before diagnosis.

Coarse facial features

Many Sanfilippo patients tend to develop coarse facial features. This may include thick nostrils, lips, and outer ears. Patients may also have coarse hair, such as thick eyebrows that meet above the nose and excessive facial and body hair. Patients may also have slightly larger heads (macrocephaly) and tongues (macroglossia) than usual.

Behavioral symptoms

Children with Sanfilippo syndrome frequently exhibit behavioral issues, often starting between the ages of 3 to 5 (depending on subtype). These issues tend to considerably affect the lives of family members, and can resemble those of autism.

The most frequently reported behavioral problems include hyperactivity, compulsive behaviors, aggression, mouthing and biting, and unusual outbursts of laughter, screaming, or crying.

Sleep disturbances

Most Sanfilippo syndrome patients (87% to 92%) develop some form of sleep disturbance. These can range from a child having a hard time settling down for bed, to waking up early, waking up frequently during the night, chewing on sheets and pillows, and unusual nighttime behaviors like singing, crying, or laughing.

As sleep disturbances progress, a child’s daytime behavioral problems typically worsen.


As a child with Sanfilippo ages, seizures become more common. In the study mentioned above, the median age for start of seizures was 8.7. Caused by a sudden surge of electrical activity in the brain, seizures usually last for a few minutes and affect a person’s movement, behavior, and levels of consciousness.

Hearing loss

Another common symptom of Sanfilippo syndrome is hearing loss. Patients tend to have ear infections that can lead to conductive hearing loss (loss caused by a failure of the sound waves to travel through the ear). As they get older, sensorineural hearing loss (caused by damage to the nerves of the ear) is more common, and most likely due to the buildup of heparan sulfate in nerve cells.

Loss of cognitive and motor skills

In its later stages, children with Sanfilippo syndrome begin to lose previous motor skills, including that of speaking, walking, sitting, and swallowing, as well as cognitive abilities like language and understanding.  They become increasingly dependent on care. Their current life expectancy is reported to be between 10 and 20 years of age.


Last updated: Jan. 26, 2021


Sanfilippo Syndrome News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.