Bereavement and remembrance
Haematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT) have transformed survival in Hurler syndrome (severe MPS I, MPS I-H). Many children now live into adolescence and adulthood who would once have died very young. At the same time, most still carry a significant burden of disease that current treatments cannot fully correct.
This page explains the remaining, or “unmet”, medical and quality-of-life needs in Hurler syndrome after HSCT and/or ERT, and why these gaps guide ongoing research and care.
Progress and limits, side by side
HSCT and ERT have brought major advances:
- Longer survival for many children
- Better control of some systemic features
- Improved outcomes when treatment is given very early
However, they do not cure Hurler syndrome. Important problems often remain, including:
- Damage that occurred before treatment
- Organs and tissues that current treatments do not reach well, especially brain, bone and cartilage
- Ongoing treatment burden and long-term complications
Understanding these unmet needs is essential to:
- Give families and adults realistic expectations
- Plan long-term multidisciplinary care
- Design better research studies and therapies for the future
What has improved
- Improved survival compared with no treatment
- Better general health and growth in early years
- Stabilisation or improvement of some organ functions
The goal of unmet-need research is not to minimise progress, but to be honest about what current treatments still leave behind.
What remains
- Residual organ damage (heart valves, airways, bones, joints, eyes, ears)
- Neurocognitive and functional challenges, especially if treatment started later
- Chronic pain, fatigue and limited mobility
- Frequent medical appointments, investigations and surgeries
Which body systems remain affected?
Even after successful HSCT and/or long-term ERT, many people with MPS I-H have persistent problems across multiple systems.
Brain and cognition
- Developmental delay or learning difficulties, especially when HSCT is performed later
- Difficulties with memory, attention and processing speed
- Impact on schooling, independence and employment potential
Skeleton, joints and growth
- Progressive spinal abnormalities (kyphosis/scoliosis)
- Hip dysplasia, joint contractures and limited range of movement
- Short stature, abnormal gait and frequent orthopaedic surgery
- Chronic musculoskeletal pain and reduced physical stamina
Heart and circulation
- Residual or progressive valve disease, even after HSCT/ERT
- Risk of cardiac surgery in childhood or adulthood
- Ongoing need for specialist cardiology follow-up
Airways and lungs
- Upper airway narrowing, sleep-disordered breathing and obstructive sleep apnoea
- Difficulties with anaesthesia due to airway anatomy
- Recurrent respiratory infections in some patients
Hearing and communication
- Conductive and/or sensorineural hearing loss
- Recurrent ear infections and grommet surgeries
- Impact on speech, language and learning if not identified early
Vision
- Corneal clouding and other ocular changes that may affect sight
- Need for regular ophthalmology follow-up and, in some cases, surgery
Endocrine and general health
- Growth hormone and puberty issues in some patients
- Fatigue, sleep disturbance and reduced exercise tolerance
This pattern of residual multisystem morbidity means that survivors after HSCT/ERT still require lifelong, specialised, multidisciplinary care.
Beyond organ tests and survival curves
Unmet need is not only about medical tests. It is also about how life feels and what people can do day to day.
For children and young people
- Missing school for hospital visits, operations and recovery
- Difficulty keeping up physically with peers in play, sports and trips
- Challenges with concentration, learning pace and exam demands
- Feelings of difference, frustration or exclusion
For adults with Hurler syndrome
- Limitations in work choices and hours due to fatigue, pain or mobility
- Barriers to independent living, driving and travel
- Difficulties in forming or maintaining relationships when health needs are high
- Ongoing psychological impact of living with a rare, lifelong condition
For families and carers
- Emotional strain of repeated decisions about surgeries and procedures
- Time and financial costs of travel, appointments, equipment and adaptations
- Impact on siblings and family life, including work and housing choices
These quality-of-life issues are a central part of the unmet need narrative.
Unmet need is not the same everywhere
Unmet need is influenced by where a child is born and how quickly they are diagnosed. Common gaps include:
- Delayed diagnosis, especially where awareness is low or newborn screening is not in place
- Variation in access to specialist centres able to perform HSCT safely
- Unequal access to ERT, monitoring and multidisciplinary follow up
- Barriers related to geography, health system structure, funding and insurance
Earlier diagnosis and treatment can significantly influence outcomes, but globally this is still not consistently achieved.
Biological and practical limitations
Despite their benefits, HSCT and ERT have inherent limitations:
Further detail from the source pages
Further detail6 sections
1 Timing
Damage that occurs before treatment, especially in the brain and skeleton, may be only partially reversible or not reversible at all
Distribution
Standard ERT does not cross the blood–brain barrier well and has limited penetration into bone and cartilage
Risk and burden
HSCT involves significant short-term risk; ERT involves life-long regular infusions, venous access, and possible infusion reactions
Incomplete correction
Even with good engraftment or long-term ERT, some tissues continue to store GAGs and deteriorate over time
These biological realities are a key reason why new approaches are being explored, including advanced delivery systems, gene therapy and combination strategies.
How unmet need shapes future science
The pattern of residual disease after HSCT/ERT directly informs current research priorities, for example:
Unmet need is not only a problem to describe, but a roadmap for what research should focus on next.
For families and adults
Making sense of “unmet need” in your own life
- It is possible to be grateful for treatment and still recognise real limitations and challenges
- If you or your child have ongoing problems after HSCT or ERT, it does not mean treatment failed; it reflects the current limits of what medicine can do
- Asking about long-term risks, expected complications and quality-of-life issues is appropriate and important
- You can advocate for access to specialist follow up, pain management, mental health support, educational support and practical help
- Participating in registries or research, when feasible, may help improve knowledge for future families
Understanding unmet need can support realistic hope and better planning, rather than pessimism.
Further detail — part 26 sections
For clinicians and researchers
From survival to long-term lived outcomes
In clinical care
- Move beyond survival and single organ metrics to include pain, function, schooling, family burden and mental health
- Proactively screen for residual complications using structured protocols
- Work closely with families to understand what outcomes matter most to them
In research
- Design trials and studies that capture long-term outcomes, not just short-term biochemical or imaging changes
- Incorporate patient reported outcomes and quality-of-life measures
- Report negative or neutral findings to give a complete picture
- Collaborate across centres and countries to increase sample sizes and diversity
Embedding unmet-need thinking into every level of work is essential to meaningful progress.
Key points about unmet need in Hurler syndrome
- HSCT and ERT have improved survival and some clinical outcomes, but do not cure Hurler syndrome.
- Many survivors live with residual multisystem morbidity, including neurocognitive, skeletal, cardiac, respiratory, hearing and visual problems.
- Quality-of-life impacts for patients and families remain substantial, covering education, work, independence and mental health.
- Global inequalities in diagnosis, access to HSCT/ERT and long-term multidisciplinary care are major contributors to unmet need.
- These gaps shape current and future research, guiding the development of therapies and care models that aim to address brain, bone, cartilage and lived experience more effectively.
Research hub
Main research themes in Hurler syndrome
Natural history and outcomes
Disease course and impact of current treatments
Treatments and care
HSCT, ERT and supportive care
Living with Hurler syndrome
Everyday life, school, work and planning ahead
Further detail — part 32 sections
Support and community
Organisations, support groups and practical help
Glossary
Definitions of key scientific and clinical terms