Supporting Patients and Families Every Step of the Way

Hurler syndrome, also called MPS I-H, is a rare inherited condition. Children with Hurler syndrome have very low or absent activity of an enzyme called alpha-L-iduronidase (IDUA). Without enough IDUA, natural substances called glycosaminoglycans (GAGs) build up inside cells and gradually affect many parts of the body, including the bones, heart, lungs, and brain.

Cause

IDUA enzyme deficiency due to changes in the IDUA gene.

Inheritance

Inherited in an autosomal recessive pattern.

Pattern

Progressive condition that affects multiple organ systems.

Early signs that often lead to diagnosis

Symptoms usually start in infancy and may become more obvious over the first few years of life. Families often notice a pattern rather than one single symptom.

Infancy

Hernias, frequent infections, mild developmental delay, and early facial changes.

Toddler years

Joint stiffness, reduced mobility, enlarged abdomen, snoring or noisy breathing.

Why timing matters

Early referral helps the specialist team plan treatment more quickly.

Diagnosis and next steps

If Hurler syndrome is suspected, or if newborn screening is positive for MPS I, families are usually referred urgently for confirmatory testing and specialist review. A positive newborn screening result is not a diagnosis by itself, and more tests are needed.

1

Confirmatory tests

IDUA enzyme testing, urine GAGs, and IDUA gene analysis are commonly used to confirm the diagnosis.

2

Metabolic specialist referral

A specialist metabolic team coordinates assessment and helps explain the diagnosis and treatment pathway.

3

Treatment planning

The team discusses treatment timing, transplant suitability, enzyme therapy, and urgent supportive care needs.

4

Family support and care coordination

Families are usually supported through hospital visits, practical planning, and links to trusted support organisations.

Questions you can ask your specialist team

It is completely normal to feel overwhelmed. Bringing a written list of questions can help during appointments.

?

Diagnosis and severity

What tests confirmed the diagnosis, and what do they show about severity and urgency?

?

Treatment options now

Is HSCT being considered, is ERT needed now, and what is the expected timeline?

?

Specialist monitoring

Which specialists will be involved (heart, lungs, orthopaedics, ENT, hearing, eyes, dental, neurodevelopment)?

?

Emergency plan

Who should we contact if breathing, surgery, anaesthesia, or sudden health issues arise?

Tip: Keep a folder (paper or digital) with letters, scan results, medicines, and clinic summaries. It makes appointments and emergencies much easier.

Current treatment and care

Current care for severe MPS I-H is built around three pillars: haematopoietic stem cell transplantation (HSCT), enzyme replacement therapy (ERT with laronidase), and long-term multidisciplinary supportive care. Families often need all three parts of the care system, even if one treatment is the main focus.

HSCT

Stem cell transplant

HSCT aims to provide a long-term source of enzyme-producing cells and is a key disease-modifying treatment for many children with severe MPS I-H.

• Most time-sensitive part of the pathway
• Best outcomes when done early
• Can help protect brain function
• Does not fully remove long-term care needs

ERT

Enzyme replacement therapy

ERT with laronidase is given as regular intravenous infusions and can help many body organs and tissues by reducing GAG storage.

• Often used before transplant and in ongoing care
• Can improve many somatic symptoms
• Does not adequately treat the brain
• Works as part of a wider care plan

Supportive care

Multidisciplinary long-term care

Because Hurler syndrome affects many organs, supportive care remains essential before and after HSCT or ERT.

• Heart, lung, airway, hearing and vision care
• Orthopaedic and mobility support
• Dental, nutrition and growth support
• Developmental and school planning

Living with Hurler syndrome

Hurler syndrome affects the whole family. Alongside hospital care, many families need help with education, practical routines, emotional support, and coordination between different teams. Building a support network can reduce isolation and make day to day life more manageable.

Hospital and appointments

Ask for a named point of contact, keep appointment notes, and bring a written question list each time.

Education and school planning

Early school support planning can help with learning, mobility, communication, and attendance around treatment.

Mental health and family wellbeing

Parents, siblings, and carers may all need emotional support. Peer groups and counselling can help.

Speech, hearing, and vision

Regular reviews can support communication, learning, and social confidence over time.

Mobility and daily adaptations

Joint stiffness and skeletal issues can affect comfort and independence, so practical adaptations matter.

Transition and long-term planning

As children grow, families may need support planning for adult services and long-term follow-up.

If you are a parent, family member, or carer, you can request a Dawn Patient and Family Information Pack. We can send a practical pack to help you organise information, prepare for appointments, and find trusted resources.

What is included in the pack

We can provide a simple, family-friendly pack to help you prepare for the next stage of care and find trusted information.

• ✓Plain-language overview of Hurler syndrome (MPS I-H)
• ✓Diagnosis and care pathway checklist for appointments
• ✓Questions to ask your specialist team
• ✓Overview of HSCT, ERT, and supportive care
• ✓Practical support and community signposting
• ✓Links to detailed resources on HurlerSyndrome.org

If your child has urgent symptoms, breathing concerns, or is due for surgery or anaesthesia, please contact your specialist medical team or emergency services immediately.

You can also adapt this panel into a downloadable PDF section later if you want a direct "Download starter guide" option.

Trusted resources

Useful pages from our sister site, HurlerSyndrome.org

For detailed educational content, visit HurlerSyndrome.org. It provides patient and family focused information on diagnosis, treatment, supportive care, and living with Hurler syndrome.

Dawn Therapeutics status

Dawn Therapeutics is a preclinical biotechnology company working on tissue-targeted delivery platforms and a lead programme in Hurler syndrome. We do not have a clinical trial open at this time, but we are committed to sharing clear educational information and supporting respectful communication with families.

For medical decisions, diagnosis, treatment timing, or emergency care, always follow your metabolic specialist team, transplant team, and local treating clinicians.

Partner, clinician, or charity contact

If you are a clinician, patient charity, or support organisation and would like to collaborate on family education materials, you can use the same request form above and select your role in the form.

Transparency

We will always keep you informed about progress, risks, and benefits.

Compassion

Your voice matters in our decision-making.

Access

We aim to make our therapies available globally, not just in select markets.