
Living with Mucopolysaccharidosis, MPS-III-D
A rare, progressive genetic condition that affects how the body breaks down sugars in the brain, causing worsening thinking and behavior changes.
Understanding Mucopolysaccharidosis, MPS-III-D
People cannot break down heparan sulfate, so it builds up and damages brain cells. Symptoms can include worsening thinking and memory, aggressive behavior, hyperactivity, seizures, hearing loss, vision loss, and sleeping only a few hours at a time.
Signs & symptoms
Symptoms vary from person to person. GARD lists these among the most common:
- Delayed speech and language development
- Aggressive behavior and agitation
- Sleep disturbance
- Coarse facial features
- Changes in how a person walks
- Elbow stiffness (contracture)
Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.
Diagnosis
- 1Talk with your doctor
Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.
- 2See a specialist
Specialists who may be involved include bone and joint specialists, brain and nervous system specialists, eye disease specialists and genetic specialists.
- 3Consider genetic testing
Changes in GNS are linked to this condition. Genetic testing and counseling can help confirm a diagnosis and explain what it means for your family.
- 4Connect with expert centers
World Craniofacial Foundation and Epilepsy Foundation may keep lists of experts for this condition.
Care & treatment
- Care team
- Bone and joint specialists (orthopedists or orthopedic surgeons); Brain and nervous system specialists (neurologists); Eye disease specialists (ophthalmologists); Genetic specialists (geneticists)
- Expert care
- Expert lists: World Craniofacial Foundation, Epilepsy Foundation
- Treatment
- GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
- Research
- Clinical trials and observational studies may be options. See the research section below.
General information, not medical advice. Your care team makes the decisions.
Everyday life
Living with a rare condition is easier with support.
- Connect with Cure Sanfilippo Foundation and other patient organizations
- Keep notes on symptoms, changes and questions for appointments
- Ask about patient registries that help research
- Look into financial aid and travel resources for care visits
Quick facts
This condition is caused by changes in the GNS gene, so an enzyme called N-acetylglucosamine 6-sulfatase does not work properly. It is autosomal recessive, which means a child inherits a changed copy of the gene from each parent.
Also known as: deficiency of n-acetylglucosamine-6-sulfatase; glucosamine n-acetyl-6-sulfatase deficiency; gns deficiency; mps 3d; mps iii d; mps iii-d - mucopolysaccharidosis iii-d
Patient organizations
- Cure Sanfilippo FoundationMucopolysaccharidosis, MPS-III-D · United States
- National MPS SocietyMucopolysaccharidosis, MPS-III-D · United States
- Team Sanfilippo FoundationMucopolysaccharidosis, MPS-III-D · United States
- World Craniofacial FoundationCraniofacial anomalies · United States
- Children's Craniofacial AssociationCraniofacial anomalies · United States
- FACES: The National Craniofacial AssociationCraniofacial anomalies · United States
- myFaceCraniofacial anomalies · United States
- Epilepsy FoundationEpilepsy · United States
You are more than your diagnosis
Perspectives from people navigating life with Mucopolysaccharidosis, MPS-III-D.
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