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Lysosomal storage diseases

Sanfilippo syndrome type A (MPS IIIA)

A lysosomal storage disease that begins in childhood and mainly affects the brain.

Not part of the panel of Türkiye's National Newborn Screening Programme (heel-prick test). Source

Prepare an emergency card

This page is translated from the Turkish original.

This disease is followed through the “Lysosomal storage diseases” group.

Understanding the disease

This section has not yet been reviewed by a physician. It summarises patient information from sources such as MedlinePlus, Orphanet and the NHS in plain language. The disease can differ from person to person; talk to your doctor about diagnosis and treatment.

What happens in this disease?

The body lacks an enzyme that breaks down a sugar called heparan sulfate. The substance builds up in cells and affects the brain most of all. Type A often begins earlier and progresses faster. It is a disease that progresses over time and shortens life.

Which symptoms can occur?

Symptoms often begin between 1-4 years of age, after a period of normal development. First behavior problems, then loss of skills, come to the fore.

  • In the early stage, infections, bowel problems or mild developmental delay
  • Restlessness, hyperactivity and temper tantrums (common)
  • Severe sleep problems (common)
  • Features similar to autism (in some children)
  • Over time, loss of speech, learning and movement skills
  • In the later stage, seizures and difficulty swallowing
  • Mildly coarse facial features, joint stiffness and hearing loss

How is it diagnosed?

At least two tests are needed for the diagnosis. The level of heparan sulfate in the urine is checked. The enzyme deficiency is shown in the blood, or the gene change is found with a genetic test.

Treatment and care

Today, care is supportive, and different specialists work together. The aim is to preserve the child's abilities and quality of life. Methods such as enzyme therapies and gene therapy are being researched. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The disease is passed on through recessive inheritance. The mother and father are often healthy carriers. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. Genetic counselling is recommended for brothers and sisters and for future pregnancies.

Source: MedlinePlus Genetics — Mucopolysaccharidosis type III · Orphanet — Mucopolysaccharidosis type 3

Key facts

How common is it?
Prevalence: 1-9 per 1 000 000 (Europe) · Birth prevalence: 1-9 per 100 000 (Worldwide)
How is it inherited?
Autosomal recessive
Gene(s) involved
SGSH

These facts are taken from Orphanet and MedlinePlus records (last checked: October 7, 2026). Frequency values are approximate ranges.

You are not alone: patient associations in Türkiye

Non-profit patient and family organizations in Türkiye working on this disease or disease group. Links are for information; Doktorclub is not affiliated with these organizations and does not endorse them.

For all rare diseases: Nadir Hastalıklar Federasyonu

Links checked on October 8, 2026.

Guides related to this disease

  • Rare disease at school · Telling the school, medicines and emergency plan, inclusion and BEP, support education room, absences, LGS/YKS arrangements, peer bullying.

Support and help

Doktorclub does not diagnose, recommend treatments or refer you to hospitals or doctors. These pages are meant to help you talk with your doctor.

News about MPS IIIA

Clinical trials (ClinicalTrials.gov)

A clinical trial is a regulated study that tests whether a new treatment is safe and whether it works, in patients who volunteer. Most trials look for a certain age, genetic change and health condition. Taking part is voluntary.

This list is not a treatment recommendation. Treatments tested in phase 1–3 trials are investigational (experimental): their efficacy and safety have not yet been proven and they are not approved treatments. Taking part depends on each trial’s criteria and a physician’s assessment; the first step is to talk to the doctor who manages your care.

Questions you can ask your doctor

  • Could this trial be suitable for us?
  • If we take part, how would current treatment and check-ups be affected?
  • Where does the trial take place, and how are travel and accommodation handled?
  • What happens if we want to leave the trial?

ClinicalTrials.gov lists 11 active interventional studies for this disease. 3 are recruiting now; 1 has a site in Türkiye. Last checked: October 7, 2026.

Selected records (studies with a site in Türkiye first):

See all studies on ClinicalTrials.gov · Joining clinical trials

Lysosomal storage diseases: other news

Medical codes (for talking with your doctor and finding sources)

These codes identify the disease in international classifications and databases. They can help when you talk with your doctor or look for reliable sources.

Orphanet code: ORPHA:79269

No separate ICD-11 code; WHO classifies this disease under: 5C56.3Y (Other specified mucopolysaccharidosis)

Codes checked against WHO ICD-11 and Orphanet on October 6, 2026.

This page provides general information and does not replace diagnosis or treatment. Talk to your doctor about symptoms, diagnosis and treatment.

The information on these pages is for general information only and does not replace medical advice. Talk to your doctor about diagnosis and treatment decisions. In an emergency in Türkiye, call 112.

Every update is based on an open source and labeled with its level of evidence. No advertising and no drug brand names. Our scientific principles

This page was translated from Turkish by the Doktorclub editorial team.