Long-term functional outcomes of children with hurler syndrome treated with unrelated umbilical cord blood transplantation

Enzymatic testing for mucopolysaccharidosis type I in Kuwaiti newborns: a preliminary study toward newborn screening

Mucopolysaccharidosis type I (MPS I) is an autosomal recessive lysosomal storage disorder characterized by deficient or absent α-L-iduronidase (IDUA) enzyme activity due to pathogenic variants in the IDUA gene. Early treatment with hematopoietic stem cell transplantation and/or enzyme replacement therapy is associated with improved outcomes in this progressive multisystem disease. The diagnosis is usually delayed due to late presentation and non-specific symptoms, which result in high morbidity and mortality. The incidence of MPS I is unknown in Kuwait. This pilot study was undertaken to screen MPS I in all Kuwaiti neonates born at Farwaniya Hospital (FH), a major center in Kuwait, over 12 months. This study examined the incidence of MPS I for inclusion in the national newborn screening (NBS) to enable its early detection and adequate treatment. All Kuwaiti neonates born at FH between December 2021 and December 2022 were screened for MPS I. The screening consisted of determining IDUA enzyme activity in dried blood spot-derived samples using tandem mass spectrometry. A follow-up genetic analysis of the IDUA gene has been planned to screen the cases with diminished IDUA enzyme activity as second-tier testing. A total of 618 newborns, including 331 (54%) boys and 287 (46%) girls, were screened. Of them, 20 had deficient IDUA enzyme activity but showed negative genetic testing. However, we have diagnosed one additional female infant with MPS I who belonged to FH, but the parents chose to deliver in a private hospital. The molecular genetic study revealed the presence of a previously reported pathogenic nonsense variant in the IDUA c.1882C>T, which is associated with severe phenotype. That being included, MPS I is estimated to be approximately 0.2% of all screened cases in Kuwait. Our study is the first to evaluate the incidence of MPS I in Kuwait. Given the single center, small number of screened infants, and the short study duration thus far, it is premature to calculate the incidence. It is anticipated that as the study continues, we would be able to estimate the incidence in our population correctly. Screening newborns in all maternity hospitals in Kuwait is necessary to calculate the actual incidence of this severe disorder. Still, our preliminary data support the inclusion of MPS I in national NBS program to allow early initiation of treatment and thus improve disease outcome.

Causes of death in mucopolysaccharidoses

Mucopolysaccharidoses are inherited metabolic diseases caused by mutations in genes encoding enzymes required for degradation of glycosaminoglycans. A lack or severe impairment of activity of these enzymes cause accumulation of GAGs which is the primary biochemical defect. Depending on the kind of the deficient enzyme, there are 12 types and subtypes of MPS distinguished. Despite the common primary metabolic deficit (inefficient GAG degradation), the course and symptoms of various MPS types can be different, though majority of the diseases from the group are characterized by severe symptoms and significantly shortened live span. Here, we analysed the frequency of specific, direct causes of death of patients with different MPS types, the subject which was not investigated comprehensively to date. We examined a total of 1317 cases of death among MPS patients, including 393 cases of MPS I, 418 cases of MPS II, 232 cases of MPS III, 45 cases of MPS IV, 208 cases of MPS VI, and 22 cases of MPS VII. Our analyses indicated that the most frequent causes of death differ significantly between MPS types, with cardiovascular and respiratory failures being predominant in MPS I, MPS II, and MPS VI, neurological deficits in MPS III, respiratory issues in MPS IV, and hydrops fetalis in MPS VII. Results of such studies suggest what specific clinical problems should be considered with the highest priority in specific MPS types, apart from attempts to correct the primary causes of the diseases, to improve the quality of life of patients and to prolong their lives.

Evolving therapies in neuronopathic LSDs: opportunities and challenges

Lysosomal storage disorders (LSD) are multisystemic progressive disorders caused by genetic mutations involving lysosomal function. While LSDs are individually considered rare diseases, the overall true prevalence of these disorders is likely higher than our current estimates. More than two third of the LSDs have associated neurodegeneration and the neurological phenotype often defines the course of the disease and treatment outcomes. Addressing the neurological involvement in LSDs has posed a significant challenge in the rapidly evolving field of therapies for these diseases. In this review, we summarize current approaches and clinical trials available for patients with neuronopathic lysosomal storage disorders, exploring the opportunities and challenges that have emerged with each of these.

Burden of Morbidity after Allogeneic Blood or Marrow Transplantation for Inborn Errors of Metabolism: A BMT Survivor Study Report

Survival after blood or marrow transplantation (BMT) for inborn errors of metabolism (IEM) is excellent; however, the burden of morbidity in long-term survivors of BMT for IEM remains understudied. This study examined the risk of chronic health conditions (CHC) in ≥2-year survivors of allogeneic BMT for IEM performed between 1974 and 2014 using the BMT Survivor Study. In this retrospective cohort study, participants (or their parents; n = 154) reported demographic data and CHCs (graded using Common Terminology Criteria for Adverse Events version 5), and transplantation characteristics were obtained from institutional databases. Unaffected siblings (n = 494) served as a comparison group. Logistic regression was used to estimated the odds of severe/life-threatening CHCs compared with siblings. Cox proportional hazards regression was used to estimate factors associated with severe/life-threatening/fatal CHCs in survivors of BMT for IEM. Survivors of allogeneic BMT for IEM (leukodystrophies, 43.5%; mucopolysaccharidoses, 41.0%) were at 12.5-fold higher odds of severe/life-threatening CHCs (95% confidence interval [CI], 5.4 to 28.9) compared with their siblings. The mean 10-year post-BMT cumulative incidence of grade 3-5 CHCs was 47.5 ± 4.0%. Reduced-intensity conditioning (RIC) was associated with a 2.7-fold higher risk (95% CI, 1.2 to 6.2; P = .02) of any grade 3-5 CHC, a 6.7-fold higher risk of grade 3-5 cardiopulmonary conditions (95% CI, 1.3 to 35.4), and a 3.0-fold higher risk of severe hearing/vision deficits (95% CI, 1.4 to 6.6). Older (age >26 years) BMT survivors were significantly less likely to graduate from college (odds ratio [OR], 0.3; 95% CI, 0.1 to 0.7) or marry (OR, 0.01; 95% CI, 0.004 to 0.07) compared with their siblings. Survivors of BMT for IEM carry a significant burden of morbidities, which affects their ability to attain adult milestones. Efforts to reduce chronic health conditions in this population are needed.

Blood and Marrow Transplant Clinical Trials Network State of the Science Symposium 2021: Looking Forward as the Network Celebrates its 20th Year

In 2021 the BMT CTN held the 4th State of the Science Symposium where the deliberations of 11 committees concerning major topics pertinent to a particular disease, modality, or complication of transplant, as well as two committees to consider clinical trial design and inclusion, diversity, and access as cross-cutting themes were reviewed. This article summarizes the individual committee reports and their recommendations on the highest priority questions in hematopoietic stem cell transplant and cell therapy to address in multicenter trials.

Long term disease burden post-transplantation: three decades of observations in 25 Hurler patients successfully treated with hematopoietic stem cell transplantation (HSCT)

BACKGROUND

Mucopolysaccharidosis type I-Hurler syndrome (MPSI-H) is a lysosomal storage disease characterized by severe physical symptoms and cognitive decline. Early treatment with hematopoietic cell transplant (HSCT) is critical to the survival of these patients. While survival rates and short-term outcomes are known to be improved by HSCT, the long-term cognitive, adaptive and psychosocial functional outcomes of children with (MPSI-H) post-HSCT are not well documented. This manuscript focuses on retrospective long-term follow-up (7-33 years) of 25 MPSI-H patients, transplanted between 1986 and 2011.

RESULTS

The median age at transplantation was 21 months (range 12-57 months). Except for one death, all successfully transplanted MPSI-H patients surviving at least 1 year after HSCT are alive to-date, with a median age of 21 years (range 8-36 years) at the last follow-up evaluation. A majority of HSCT grafts were bone marrow transplants (BMT), resulting in durable full chimerism in 18 (72%). Pre-HSCT, the onset of first symptoms occurred very early, at a median age of 3 months (range birth-16 months). The most prevalent symptoms before MPSI-H diagnosis involved progressive dysostosis multiplex; almost all patients suffered from hip dysplasia and thoracolumbar spine Kyphosis. Despite HSCT, considerable residual disease burden and ensuing corrective surgical interventions were observed in all, and at every decade of follow-up post HSCT. Late-onset psychiatric manifestations were significant (n = 17 patients; 68%), including depression in 13 patients at a median onset age of 18 years (range 13-31 years), hyperactivity and attention deficit disorder (n = 4), and multiple acute psychotic episodes (APE), independent of depression observed (n = 3) at a median onset age of 18 years (range 17-31 years). The adult Welscher Intelligence Scale results (n = 16) were heterogenous across the four scale dimensions; overall lower scores were observed on both working memory index (median WMI = 69.5) and processing speed index (median PSI = 65), whereas verbal comprehension index (median VCI = 79) and perceptual reasoning index (median PRI = 74) were higher.

CONCLUSION

With advanced treatment options, MPSI-H are living into 3rd and 4th decades of life, however not disease free and with poor adaptation. Residual disease (loss of mobility, limited gross and fine motor skills; low cognitive ability; suboptimal cardiopulmonary function, vision and hearing) negatively impacts the quality of life and psychosocial functioning of affected individuals.

Mucopolysaccharidosis Type I: Current Treatments, Limitations, and Prospects for Improvement

Mucopolysaccharidosis type I (MPS I) is a lysosomal disease, caused by a deficiency of the enzyme alpha-L-iduronidase (IDUA). IDUA catalyzes the degradation of the glycosaminoglycans dermatan and heparan sulfate (DS and HS, respectively). Lack of the enzyme leads to pathologic accumulation of undegraded HS and DS with subsequent disease manifestations in multiple organs. The disease can be divided into severe (Hurler syndrome) and attenuated (Hurler-Scheie, Scheie) forms. Currently approved treatments consist of enzyme replacement therapy (ERT) and/or hematopoietic stem cell transplantation (HSCT). Patients with attenuated disease are often treated with ERT alone, while the recommended therapy for patients with Hurler syndrome consists of HSCT. While these treatments significantly improve disease manifestations and prolong life, a considerable burden of disease remains. Notably, treatment can partially prevent, but not significantly improve, clinical manifestations, necessitating early diagnosis of disease and commencement of treatment. This review discusses these standard therapies and their impact on common disease manifestations in patients with MPS I. Where relevant, results of animal models of MPS I will be included. Finally, we highlight alternative and emerging treatments for the most common disease manifestations.

Outcome After Cord Blood Transplantation Using Busulfan Pharmacokinetics-Targeted Myeloablative Conditioning for Hurler Syndrome

We report the outcomes of cord blood transplantation (CBT) with a busulfan (Bu) pharmacokinetics-targeted myeloablative conditioning regimen in 97 children with Hurler syndrome (HS) performed between 2004 and 2016. The median age at CBT was 10.8 months (range, 0.23 to 63.2 months). The median duration of follow-up for surviving patients was 4.2 years (range, 1.0 to 12.8 years). Five-year overall survival (OS) and engrafted survival (ES) were 88% and 79%, respectively. OS was 95% in patients who received Bu/fludarabine (Flu)/antithymocyte globulin (ATG) conditioning, 90% in those who received Bu/cyclophosphamide (Cy)/ATG, and 74% in those who received Bu/Cy/alemtuzumab (P = .02). ES was 84% for recipients of Bu/Flu/ATG conditioning, 83% for recipients of Bu/Cy/ATG conditioning, and 65% for recipients of Bu/Cy/alemtuzumab conditioning (P = .34). Receipt of washed CB units (P = .03) and HLA matching ≤6/10 (P = .02) were associated with significantly lower ES. The 1-year cumulative incidence of graft failure was 11% (95% confidence interval, 6% to 21%). Five patients (5%) had grade III-IV acute GVHD, 5 patients had limited chronic GVHD, and 1 patient had extensive GVHD. The incidence of veno-occlusive disease was higher in patients conditioned with Bu/Cy compared with those conditioned with Bu/Flu (19% [n = 10] versus 5% [n = 2]: P = .03). Of the 11 patients with graft failure, 8 (73%) were aplastic, and 3 (27%) had autologous reconstitution. Of 11 patients with graft failure, 9 underwent a second CBT, and 8 (89%) survived. Full donor chimerism was observed in 89% patients after first CBT and in all patients after second CBT. Survival after CBT for HS has improved, but better strategies are still needed to improve graft outcomes.

Therapy development for the mucopolysaccharidoses: Updated consensus recommendations for neuropsychological endpoints

Neurological dysfunction represents a significant clinical component of many of the mucopolysaccharidoses (also known as MPS disorders). The accurate and consistent assessment of neuropsychological function is essential to gain a greater understanding of the precise natural history of these conditions and to design effective clinical trials to evaluate the impact of therapies on the brain. In 2017, an International MPS Consensus Panel published recommendations for best practice in the design and conduct of clinical studies investigating the effects of therapies on cognitive function and adaptive behavior in patients with neuronopathic mucopolysaccharidoses. Based on an International MPS Consensus Conference held in February 2020, this article provides updated consensus recommendations and expands the objectives to include approaches for assessing behavioral and social-emotional state, caregiver burden and quality of life in patients with all mucopolysaccharidoses.

Biochemical and clinical response after umbilical cord blood transplant in a boy with early childhood-onset beta-mannosidosis

BACKGROUND

Deficiency in the enzyme β-mannosidase was described over three decades ago. Although rare in occurrence, the presentation of childhood-onset β-mannosidase deficiency consists of hypotonia in the newborn period followed by global development delay, behavior problems, and intellectual disability. No effective pharmacologic treatments have been available.

METHODS

We report 2-year outcomes following the first umbilical cord blood transplant in a 4-year-old boy with early childhood-onset disease.

RESULTS

We show restoration of leukocyte β-mannosidase activity which remained normal at 2 years posttransplant, and a simultaneous increase in plasma β-mannosidase activity and dramatic decrease in urine-free oligosaccharides were also observed. MRI of the brain remained stable. Neurocognitive evaluation revealed test point gains, although the magnitude of improvement was less than expected for age, causing lower IQ scores that represent a wider developmental gap between the patient and unaffected peers.

CONCLUSION

Our findings suggest that hematopoietic cell transplant can correct the biochemical defect in β-mannosidosis, although preservation of the neurocognitive trajectory may be a challenge.

Late Mortality after Allogeneic Blood or Marrow Transplantation for Inborn Errors of Metabolism: A Report from the Blood or Marrow Transplant Survivor Study-2 (BMTSS-2)

Allogeneic blood or marrow transplantation (BMT) is currently considered the standard of care for patients with specific inborn errors of metabolism (IEM). However, there is a paucity of studies describing long-term survival and cause-specific late mortality after BMT in these patients with individual types of IEM. We studied 273 patients who had survived ≥2 years after allogeneic BMT for IEM performed between 1974 and 2014. The most prevalent IEM in our cohort were X-linked adrenoleukodystrophy (ALD; 37.3%), Hurler syndrome (35.1%), and metachromatic leukodystrophy (MLD; 10.2%). Conditional on surviving ≥2 years after BMT, the overall survival for the entire cohort was 85.5 ± 2.4% at 10 years and 73.5 ± 3.7% at 20 years. The cohort had a 29-fold increased risk of late death compared with an age- and sex-matched cohort from the general US population (95% CI, 22- to 38-fold). The increased relative mortality was highest in the 2- to 5-year period after BMT (standardized mortality ratio [SMR], 207; 95% confidence interval [CI], 130 to 308) and declined with increasing time from BMT, but remained elevated for ≥21 years after BMT (SMR, 9; 95% CI, 4 to 18). Sequelae from the progression of primary disease were the most common causes of late mortality in this cohort (76%). The use of T cell-depleted grafts in patients with ALD and Hurler syndrome was a risk factor for late mortality. Younger age at BMT and use of busulfan and cyclosporine were protective in patients with Hurler syndrome. Our findings demonstrate relatively favorable overall survival in ≥2-year survivors of allogeneic BMT for IEM, although primary disease progression continues to be responsible for the majority of late deaths.

Scope and Burden of Non-Standard of Care Hematopoietic Stem Cell Transplantation in Pediatric Leukodystrophy Patients

Inherited leukodystrophies are a group of diseases affecting central nervous system myelin that lead to death or significant health problems. Although for most leukodystrophies there are no curative treatments, for a handful of diseases hematopoietic stem cell transplantation (HSCT; bone marrow transplant) can stop disease progression, and if initiated in a timely fashion, prevent many or all neurologic and other systems involvement. However, HSCT is a complex procedure with significant morbidity and mortality risks. The study goal was to determine whether HSCT was being more widely used outside of those leukodystrophies for which HSCT is typically employed. The authors conducted a 2-year retrospective review of HSCT performed across the United States in 51 children's hospitals that are part of the Pediatric Health Information System. The authors screened for 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) codes for leukodystrophies in which HSCT is "nonstandard," including sphingolipidoses, Fabry disease, Gaucher disease, and Niemann-Pick disease, and excluded patients who had ICD-10 codes for leukodystrophies that are HSCT candidates, specifically X-linked adrenoleukodystrophy, metachromatic leukodystrophy, Krabbe disease, and Hurler disease. The authors identified 91 patients (from a total cohort of 937) with one of the nonstandard leukodystrophies who had HSCT. HSCT was performed at 20 of the hospitals, with the majority performed at only 6 hospitals. Average costs ($786 846) per patient were more than 6 times higher than patients who did not have HSCT. The data show that an unexpectedly large number of leukodystrophy patients are receiving transplants for conditions in which HSCT is not typically used, and which are associated with high medical costs.

Developmental and behavioral aspects of mucopolysaccharidoses with brain manifestations - Neurological signs and symptoms

The mucopolysaccharidoses (MPS) are a group of rare, inherited lysosomal storage disorders, caused by mutations in lysosomal enzymes involved in the degradation of glycosaminoglycans (GAGs). The resulting accumulation of GAGs in the body leads to widespread tissue and organ dysfunction. The spectrum, severity, and progression rate of clinical manifestations varies widely between and within the different MPS types. In addition to somatic signs and symptoms, which vary between the different MPS disorders, patients with MPS I, II, III, and VII present with significant neurological signs and symptoms, including impaired cognitive abilities, difficulties in language and speech, and/or behavioral and sleep problems. To effectively manage and develop therapies that target these neurological manifestations, it is of utmost importance to have a profound knowledge of their natural history and pathophysiology. This review describes the appearance and progression of neurological signs and symptoms in patients with MPS I, II, and III, based on presentations and discussions among an international group of experts during a meeting on the brain in MPS on April 28-30, 2016, and additional literature searches on this subject.

Assessments of neurocognitive and behavioral function in the mucopolysaccharidoses

The mucopolysaccharidoses (MPS) are a group of rare, inherited lysosomal storage disorders in which accumulation of glycosaminoglycans (GAGs) leads to progressive tissue and organ dysfunction. In addition to a variety of somatic signs and symptoms, patients with rapidly progressing MPS I (Hurler), II, III, and VII can present with significant neurological manifestations, including impaired cognitive abilities, difficulties in language and speech, behavioral abnormalities, sleep problems, and/or seizures. Neurological symptoms have a substantial impact on the quality of life of MPS patients and their families. Due to the progressive nature of cognitive impairment in these MPS patients, neurocognitive function is a sensitive indicator of disease progression, and a relevant outcome when testing efficacy of therapies for these disorders. In order to effectively manage and develop therapies that address neurological manifestations of MPS, it is important to use appropriate neurocognitive assessment tools that are sensitive to changes in neurocognitive function in MPS patients. This review discusses expert opinions on key issues and considerations for effective neurocognitive testing in MPS patients. In addition, it describes the neurocognitive assessment tools that have been used in clinical practice for these patients. The content of this review is based on existing literature and information from a meeting of international experts with extensive experience in managing and treating MPS disorders.

Treatment of brain disease in the mucopolysaccharidoses

The mucopolysaccharidosis (MPS) disorders are a group of lysosomal storage diseases caused by lysosomal enzyme deficits that lead to glycosaminoglycan accumulation, affecting various tissues throughout the body based on the specific enzyme deficiency. These disorders are characterized by their progressive nature and a variety of somatic manifestations and neurological symptoms. There are established treatments for some MPS disorders, but these mostly alleviate somatic and non-neurological symptoms and do not cure the disease. Patients with MPS I, II, III, and VII can present with neurological manifestations such as neurocognitive decline and behavioral problems. Treatment of these neurological manifestations remains challenging due to the blood-brain barrier (BBB) that limits delivery of therapeutic agents to the central nervous system (CNS). New therapies that circumvent this barrier and target brain disease in MPS are currently under development. They primarily focus on facilitating penetration of drugs through the BBB, delivery of recombinant enzyme to the brain by gene therapy, or direct CNS administration. This review summarizes existing and potential future treatment approaches that target brain disease in MPS. The information in this review is based on current literature and presentations and discussions during a closed meeting by an international group of experts with extensive experience in managing and treating MPS.

The mucopolysaccharidoses: advances in medical care lead to challenges in orthopaedic surgical care

The mucopolysaccharidoses (MPS) are a group of inherited lysosomal storage disorders with clinical manifestations relevant to the orthopaedic surgeon. Our aim was to review the recent advances in their management and the implications for surgical practice. The current literature about MPSs is summarised, emphasising orthopaedic complications and their management. Recent advances in the diagnosis and management of MPSs include the recognition of slowly progressive, late presenting subtypes, developments in life-prolonging systemic treatment and potentially new indications for surgical treatment. The outcomes of surgery in these patients are not yet validated and some procedures have a high rate of complications which differ from those in patients who do not have a MPS. The diagnosis of a MPS should be considered in adolescents or young adults with a previously unrecognised dysplasia of the hip. Surgeons treating patients with a MPS should report their experience and studies should include the assessment of function and quality of life to guide treatment. Cite this article: Bone Joint J 2017;99-B:1132-9.

Chiari I malformation and syringomyelia in mucopolysaccharidosis type I (Hurler syndrome) treated with posterior fossa decompression: Case report and review of the literature

Background:

Hurler Syndrome is the most severe phenotype of mucopolysaccharidosis type I. With bone marrow transplant and enzyme replacement therapy, the life expectancy of a child with Hurler syndrome has been extended, predisposing them to multiple musculoskeletal issues most commonly involving the spine.

Case Description:

This is the case report of a 6-year-old male with Hurler syndrome who was diagnosed with Chiari I malformation and cervicothoracic syringomyelia on a preoperative magnetic resonance imaging (MRI) for his thoracolumbar kyphosis. This report details the successful management of a Chiari I malformation and syringomyelia with posterior fossa decompression in a child with Hurler syndrome.

Conclusion:

Children born with MPS I can have complex spine issues that require surgical management. The most common orthopedic spinal condition for these patients, thoracolumbar kyphosis, requires evaluation with an MRI before performing surgery. This resulted in the diagnosis of a Chiari I malformation and syringomyelia in our patient with Hurler syndrome. This was successfully treated with decompression of the posterior fossa.

Cognitive endpoints for therapy development for neuronopathic mucopolysaccharidoses: Results of a consensus procedure

The design and conduct of clinical studies to evaluate the effects of novel therapies on central nervous system manifestations in children with neuronopathic mucopolysaccharidoses is challenging. Owing to the rarity of these disorders, multinational studies are often needed to recruit enough patients to provide meaningful data and statistical power. This can make the consistent collection of reliable data across study sites difficult. To address these challenges, an International MPS Consensus Conference for Cognitive Endpoints was convened to discuss approaches for evaluating cognitive and adaptive function in patients with mucopolysaccharidoses. The goal was to develop a consensus on best practice for the design and conduct of clinical studies investigating novel therapies for these conditions, with particular focus on the most appropriate outcome measures for cognitive function and adaptive behavior. The outcomes from the consensus panel discussion are reported here.

Mortality after hematopoietic stem cell transplantation for severe mucopolysaccharidosis type I: the 30-year University of Minnesota experience

BACKGROUND AND AIM

Mucopolysaccharidosis IH (MPS IH, Hurler syndrome) naturally leads to death within the first decade of life, primarily from cardiac and pulmonary causes. To determine how hematopoietic stem cell transplantation (HSCT) has altered mortality, we analyzed our institution's 30-year experience of patients with MPS IH undergoing HSCT.

METHODS

Using chart review and the National Death Index, we determined survival status of 134 patients (males = 69) with MPS IH transplanted between 9/16/1983 and 7/25/2013 on 12/31/2013. Analysis included descriptive statistics, Kaplan-Meier curves, and regression analysis by Cox proportional hazards model.

RESULTS

Overall survival (95% CI) at one- and 25-years was 70% (62-78%) and 37% (19-55%), respectively. From 2004 onward, overall survival at one- and 8-years was 84% (73-96%) and 81% (69-94%), respectively, compared to 65% (55-74%) and 57% (47-67%) prior to 2004 (Log-rank p = 0.032). Regardless of era, male survival was significantly better than female (HR 0.40, [95% CI: 0.21-0.74], p = 0.004). The cumulative incidence of death (95% CI) at 25 years was 63% (45-81%); incidence of pulmonary-related death was the highest at 27% (10-41%) compared to 8% (0.3-16%) for cardiac, 12% (6-17%) for infectious disease, and 16% (3-27%) from other complications.

CONCLUSIONS

HSCT has increased survival in MPS IH beyond the third decade of life and decreased the incidence of cardiac mortality, but deaths after the third year post-HSCT occur in excess of expected US mortality. It is important to determine if improved transplant strategies since 2004 result in better long-term survival in the current patient population.

Early disease progression of Hurler syndrome

Background

Newborn screening for mucopolysaccharidosis type I (MPS I) shows promise to improve outcomes by facilitating early diagnosis and treatment. However, diagnostic tests for MPS I are of limited value in predicting whether a child will develop severe central nervous system disease associated with Hurler syndrome, or minimal or no central nervous system involvement associated with the attenuated phenotypes (Hurler–Scheie and Scheie syndromes). Given that the optimal treatment differs between Hurler syndrome and the attenuated MPS I phenotypes, the absence of a reliable prognostic biomarker complicates clinical decision making for infants diagnosed through newborn screening. Information about the natural history of Hurler syndrome may aid in the management of affected infants, contribute to treatment decisions, and facilitate evaluation of treatment effectiveness and prognosis. Thus, the aim of this study was to characterize the progression and timing of symptom onset in infants with Hurler syndrome.

Results

Clinical data from 55 patients evaluated at a single center were retrospectively reviewed. Information about each child’s medical history was obtained following a standardized protocol including a thorough parent interview and the review of previous medical records. All patients underwent systematic physical and neurodevelopmental evaluations by a multidisciplinary team. Nearly all patients (98%) showed signs of disease during the first 6 months of life. Common early disease manifestations included failed newborn hearing screen, respiratory symptoms, difficulty latching, and otitis media. Other symptoms such as kyphosis, corneal clouding, cardiac disease, joint restrictions, and enlarged head circumference typically appeared slightly later (median age, 8–10 months). During the first 12 months, gross motor development was the most severely affected area of functioning, and a significant number of patients also experienced language delays. Cognition was typically preserved during this period.

Conclusions

In this large cohort of patients with Hurler syndrome, the vast majority showed signs and symptoms of disease during the first months of life. More research is needed to determine the extent to which early clinical manifestations of MPS I can predict phenotype and treatment outcomes.

Cognitive outcomes and age of detection of severe mucopolysaccharidosis type 1

The US Secretary of Health and Human Services recommended in February 2016 that mucopolysaccharidosis type 1 (MPS I) be added to the recommended uniform screening panel for state newborn screening programs. One of the key factors in this decision was the evidence suggesting that earlier treatment with hematopoietic cell transplantation (HCT) for the most severe form, Hurler syndrome (MPS IH), would lead to improved cognitive outcomes. Consistent evidence from peer-reviewed studies suggests that transplantation in the first year of life is associated with improved developmental quotient or intelligence quotient and continued cognitive growth, with earlier age of treatment associated with improved outcomes. However, available evidence suggests that cognitive functioning and attention can still lag behind unaffected age-matched children, leading to the need for special education services. Verbal and nonverbal cognitive abilities outcomes may be affected differently by HCT. With the recent addition of MPS I to the recommended uniform screening panel, future work is needed to evaluate the impact of earlier, presymptomatic detection and treatment initiation and other supportive therapies on cognitive outcomes.Genet Med advance online publication 26 January 2017.

Use of new imaging in detecting and monitoring ocular manifestations of the mucopolysaccharidoses

The aim of this review is to summate the eye involvement in patients with mucopolysaccharidoses (MPS) using current ocular imaging techniques, their advantages and disadvantages and how they may aid diagnosis, management and monitoring. We critically reviewed the current literature surrounding MPS and recent imaging technology as well as histology. Primary searches of PubMed and Web of Science were performed. We reviewed all papers on the topic published and summarized the findings of each medical device as well as the advantages and disadvantages of using these for the MPS patient. We discussed the potential of each of these devices to monitor potential ocular pathology in the MPS cohorts in the order of MPS subtype. We reviewed imaging techniques involving use of the Iris Camera, Pentacam, Optical Coherence Tomography (OCT) as well as ultrasound and Heidelberg OCT. The need for reliable objective quantification of eye findings in MPS has led to utilization of new imaging technologies described here, and future use will enhance our understanding of the unique eye features in MPS. In particular, we note that the Pentacam and iris camera are able to provide objective measurements of corneal haze and monitor ocular response to treatment.