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Lysosomal storage diseases

Sly syndrome (MPS VII)

A very rare inherited storage disease. The body cannot break down some large sugar molecules. Many organs are affected, and severity differs from person to person.

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?

A change in the GUSB gene reduces the enzyme beta-glucuronidase. This enzyme breaks down large sugar molecules called GAGs. GAGs build up in the cells and affect many organs. In the most severe form, fluid builds up in the baby's body before birth.

Which symptoms can occur?

Symptoms usually begin in early childhood and increase with age.

  • A large head and coarse facial features
  • A large liver and spleen, hernia
  • Heart valve problems
  • Short stature and stiff joints
  • Clouding of the clear front layer of the eye and hearing loss
  • Pauses in breathing during sleep
  • Developmental delay (in some people)
  • Numbness in the hand, called carpal tunnel (in many children)

How is it diagnosed?

GAG levels in the urine rise. The diagnosis is confirmed by measuring the enzyme in the blood or in skin cells. A genetic test for the GUSB gene can be done. Diagnosis is also possible during pregnancy.

Treatment and care

There is an approved enzyme replacement therapy for this disease. Surgery may be needed for bone problems and hernias. Because of the shape of the airways and neck, special precautions are taken before anesthesia. A stem cell transplant has been tried in a small number of patients. 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 usually healthy carriers. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. Diseases of this kind may be more common in marriages between relatives. Genetic counselling guides the family.

Source: MedlinePlus Genetics: Mucopolysaccharidosis type VII · NORD: Mucopolysaccharidosis Type VII

Key facts

How common is it?
Prevalence: <1 per 1 000 000 (Europe)
How is it inherited?
Autosomal recessive
When does it usually start?
Adolescence, Before birth, Childhood, Infancy, Newborn period
Gene(s) involved
GUSB

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 Sly syndrome

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 2 active interventional studies for this disease. 1 is recruiting now; none 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:584

No separate ICD-11 code; WHO classifies this disease under: 5C56.3Y

Codes checked against WHO ICD-11 and Orphanet on October 7, 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.