Epidemiology
Incidence of Sanfilippo syndrome varies geographically, with approximately 1 case per 280,000 live births in Northern Ireland, 1 per 66,000 in Australia, and 1 per 50,000 in the Netherlands.The Australian study estimated the following incidence for each subtype of Sanfilippo syndrome:

History
The condition is named after Sylvester Sanfilippo, the pediatrician who first described the disease in 1963. Caregiver impact
Caregivers for children with Sanfilippo syndrome face a unique set of challenges because of the diseases complex nature. There is little understanding among clinicians of the family experience of caring for patients with Sanfilippo and how a caregivers experiences change and evolve as patients age. The burden and impact on caregivers quality of life is poorly defined and best-practice guidance for clinicians is lacking.A best-practice guidance to help clinicians understand the challenges caregivers face was published July 2019 in the Orphanet Journal of Rare Diseases by a group of international clinical advisors with expertise in the care of pediatric patients with Sanfilippo, lysosomal storage disorders, and life as a caregiver to a child with Sanfilippo.The group reviewed key aspects of caregiver burden associated with Sanfilippo B by identifying and quantifying the nature and impact of the disease on patients and caregivers. Recommendations were based on findings from qualitative and quantitative research.The articles authors reported, "Providing care for patients with Sanfilippo B impinges on all aspects of family life, evolving as the patient ages and the disease progresses.
The disordered sleep in particular presents a significant problem to care providers.In the final phase of the illness, children become increasingly immobile and unresponsive, often require wheelchairs, and develop swallowing difficulties and seizures. The life-span of an affected child does not usually extend beyond late teens to early twenties.Individuals with MPS type III tend to have mild skeletal abnormalities; osteonecrosis of the femoral head may be present in patients with the severe form. Optic nerve atrophy, deafness, and otitis can be seen in moderate to severe individuals. Other characteristics include coarse facial features, thick lips, synophrys, and stiff joints.It is difficult to clinically distinguish differences among the four types of Sanfilippo syndrome. However, type A is usually the most severe subtype, characterized by earliest onset, rapid clinical progression with severe symptoms, and short survival. The median age of death for children afflicted with type A is 15.4 ± 4.1 years.It is important that simple and treatable conditions such as ear infections and toothaches not be overlooked because of behavior problems that make examination difficult. Children with MPS type III often have an increased tolerance to pain. Bumps, bruises, or ear infections that would be painful for other children often go unnoticed in children with MPS type III. Some children with MPS type III may have a blood-clotting problem during and after surgery. Genetics
Mutations in four different genes can lead to Sanfilippo syndrome. This disorder is inherited in an autosomal recessive pattern. People with two working copies of the gene are unaffected.