Sanfilippo syndrome is a type of childhood dementia

Sanfilippo syndrome, also known as mucopolysaccharidosis type III (MPS III), is a rare genetic condition causing many effects on the body but its most marked effect is progressive and fatal brain damage in children. Children with Sanfilippo have an enzyme deficiency which means they cannot process the waste (heparan sulfate) that builds up in their cells. Over time this waste becomes toxic and causes damage throughout the body but especially in the brain.

Babies are born seemingly healthy and in the early years of life will meet their normal developmental milestones. As damage occurs in the body the child may start to show signs such as frequent ear/nose/throat infections, a mild developmental or speech delay, sleep disturbance, gastrointestinal symptoms and behavioural issues.  

Although signs and symptoms often begin to be noticeable around two years of age, it can take several years to reach a diagnosis and most children are not diagnosed until 4-6 years of age. Life expectancy is typically 12-20 years.

There are four subtypes: A, B, C and D. Some children have an attenuated form of the disease that progresses more slowly.

The condition is named after Dr Sylvester Sanfilippo, an American paediatrician who first described the condition in the 1960s. There is currently no cure but clinical trials are underway and showing significant promise.