For Healthcare Professionals

What are the signs and symptoms of MPS IIIA?

Mucopolysaccharidosis type IIIA (MPS IIIA; also known as Sanfilippo syndrome type A) can present in many ways, at different ages, and may change over time. Because of these effects on brain and body, MPS IIIA is often called “childhood dementia.”

Signs and symptoms can include*:
Illustration depicting some of the possible signs and symptoms of MPS III
*
These are not all the possible signs and symptoms of MPS IIIA. Not every child with MPS IIIA will have the same types, severity, and timing of signs and symptoms.
genetic count

Over 100 other rare genetic conditions may have a similar presentation to what is seen in people with MPS IIIA.

MPS IIIA may be mistaken for other more common pediatric developmental conditions, including:

  • Autism spectrum disorder because of similar language delay and behavioral issues
  • Attention deficit hyperactivity disorder, or ADHD, because of children being hyperactive and impulsive
  • General developmental or speech delays

What this means ...

Every child with MPS IIIA is different. It’s important to tell your child’s pediatrician about any concerns that you have.

How does MPS IIIA change over time?

Children with MPS IIIA initially develop at a similar rate as their peers but then can lose cognitive abilities and motor skills over time

Chart showing the development of key milestones of an average child with MPS III and a child who does not have the condition.
Zoom to view image

MPS IIIA is considered the most severe type of MPS III and the one that progresses most rapidly. How MPS III develops over time can vary significantly from one child to the next.
Figure created by and used with permission of Cure Sanfilippo Foundation.

The signs and symptoms of MPS IIIA appear over time, with the earliest often becoming noticeable between 1 and 6 years of age.

  • Though signs of MPS IIIA may be present at birth, they can go unnoticed
  • As early as 2 years of age, development tends to slow down and often stops
  • After 3 years of age, skills may be gradually lost, including the abilities to speak, walk, and feed themselves. Behavioral issues and sleeping problems may also start to occur
  • People with MPS IIIA generally have a life expectancy of around 10 to 20 years

What this means ...

Your child’s MPS IIIA may change over time. Tell your child’s pediatrician about any changes in their condition or behavior.

Learn about the diagnosis of MPS IIIA

Diagnosis & Management