Management guidelines for mucopolysaccharidosis VI

Feasibility and efficacy of the forced oscillation technique in patients with lysosomal storage diseases

Lysosomal storage disorders (LSDs) are a diverse group of inborn errors of metabolism, which involves the storage of macromolecules within the lysosome due to the absence of or deficiency in lysosomal enzymes. In this condition, respiratory dysfunction is the common cause of morbidity and mortality. Thus, an objective measurement examination of pulmonary function, such as spirometry, is essential for the diagnosis and management of respiratory conditions. However, spirometry requires active patient involvement. Meanwhile, the forced oscillation technique (FOT) is performed during tidal breathing and is feasible in patients who cannot perform spirometry. Thus, the current study aimed to assess the feasibility and efficacy of FOT in assessing respiratory function among patients with LSD. This study was conducted at the outpatient department of Tawam Hospital, Al-Ain, the United Arab Emirates. Patients with confirmed LSD were included in the analysis. Information on respiratory history was obtained using a standardized respiratory questionnaire, and lung function was assessed using FOT. The main outcomes were respiratory resistance (Rrs5), reactance at 5 Hz (Xrs5), and area under the reactance curve (AX). In total, 35 patients with LSD were assessed. FOT was used to evaluate 16 (47%) patients. Of the patients who were successfully assessed using FOT, 10 presented with abnormal outcomes. Hence, there was an association between lung function assessed using FOT and spirometry results in these patients. FOT can help obtain lung function measurements in patients with LSD. In this study, the patients commonly presented with abnormal FOT outcomes.

Syndromic Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a progressive inherited retinal dystrophy, characterized by the degeneration of photoreceptors, presenting as a rod-cone dystrophy. Approximately 20-30% of patients with RP also exhibit extra-ocular manifestations in the context of a syndrome. This manuscript discusses the broad spectrum of syndromes associated with RP, pathogenic mechanisms, clinical manifestations, differential diagnoses, clinical management approaches, and future perspectives. Given the diverse clinical and genetic landscape of syndromic RP, the diagnosis may be challenging. However, an accurate and timely diagnosis is essential for optimal clinical management, prognostication, and potential treatment. Broadly, the syndromes associated with RP can be categorized into ciliopathies, inherited metabolic disorders, mitochondrial disorders, and miscellaneous syndromes. Among the ciliopathies associated with RP, Usher syndrome and Bardet-Biedl syndrome are the most well-known. Less common ciliopathies include Cohen syndrome, Joubert syndrome, cranioectodermal dysplasia, asphyxiating thoracic dystrophy, Mainzer-Saldino syndrome, and RHYNS syndrome. Several inherited metabolic disorders can present with RP including Zellweger spectrum disorders, adult Refsum disease, α-methylacyl-CoA racemase deficiency, certain mucopolysaccharidoses, ataxia with vitamin E deficiency, abetalipoproteinemia, several neuronal ceroid lipofuscinoses, mevalonic aciduria, PKAN/HARP syndrome, PHARC syndrome, and methylmalonic acidaemia with homocystinuria type cobalamin (cbl) C disease. Due to the mitochondria's essential role in supplying continuous energy to the retina, disruption of mitochondrial function can lead to RP, as seen in Kearns-Sayre syndrome, NARP syndrome, primary coenzyme Q10 deficiency, SSBP1-associated disease, and long chain 3-hydroxyacyl-CoA dehydrogenase deficiency. Lastly, Cockayne syndrome and PERCHING syndrome can present with RP, but they do not fit the abovementioned hierarchy and are thus categorized as 'Miscellaneous'. Several first-in-human clinical trials are underway or in preparation for some of these syndromic forms of RP.

Tracheostomy in children with mucopolysaccharidosis: A systematic review

OBJECTIVES

Children with mucopolysaccharidosis (MPS) with difficult airways may require tracheostomy, and surgery can be challenging. This review aims to study the indications, surgical aspects, postoperative complications and outcomes of tracheostomy in MPS children.

METHODS

A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted. Pubmed and Embase were searched for studies on tracheostomy in children with MPS. The Joanna Briggs Institute was used for quality appraisal.

RESULTS

A total of 9 studies were included. Three were retrospectives, one was prospective, and five were case series. Overall, 34 subjects who underwent a tracheostomy were included. The mean age was 11 years and the male/female ratio was 1.7. MPS II was the most common type included (16/34). The percentage of tracheotomized MPS children was 10 % (ranging from 3.5 % to 15.5 %). Indications for tracheostomy were: progressive or urgent airway obstruction unresponsive to conservative treatments, before a planned surgical procedure, and in case of failed intubation/extubation. Characteristics clinical features make surgery difficult and predispose complications such as tracheal granulations, wound infection, stomal narrowing, persistent of abundant secretions and tracheitis. Considering tracheostomy outcome, two patients underwent decannulation, but one of them required reinsertion tracheostomy after one year. The duration of follow-up was 8.4 and 9.98 years.

CONCLUSION

Tracheostomy is an effective means of ensuring airway patency in children with MPS and is considered essentially permanent. Management can be challenging due to typical clinical features and progression of MPS. A planned multidisciplinary approach may prevent complications.

"Mucopolysaccharidosis syndrome in a 9-Year-old boy: oral-dental management and diagnostic considerations": a case report

BACKGROUND

Mucopolysaccharidosis (MPS) comprises a group of metabolic diseases with a disorder in the function of lysosomal enzymes that lead to the accumulation of glycosaminoglycans (mucopolysaccharides) (Kubaski et al. in Diagnostics 10:161, 2020; Hampe et al. in Cells 9:1838, 2020; Tomatsu et al. Mol Genet Metab 110(1-2):42-53, 2013). At least seven variants of this disorder have been identified to date (Muenzer et al. in Pediatrics 124(6):e1228-e1239, 2009; Muenzer et al. in Eur J Pediatr 171:181-8, 2012). this study aims to report a case of mucopolysaccharidosis in a 9-year-old child. Also, the treatments and dental observations made for the child have been described. Also, a review of past articles has been done to report the types of diseases, medical and dental considerations, etc. of this disease.

CASE DESCRIPTION

the present case report describes the orofacial and systemic characteristics, diagnostic methods, and dental management of a 9-year-old boy with MPS with a one-year follow-up in association with a brief review of past articles.

CONCLUSION

Since MPS patients have many changes in their oral and dental structures, they pose many challenges for dentists. Also, these patients need considerations in dentistry due to the involvement of different body organs. Knowing the oral-dental and systemic problems of these patients can help their dentists to provide effective and safe treatment for them.

Consensus-based expert recommendations on the management of MPS IVa and VI in Saudi Arabia

BACKGROUND

Mucopolysaccharidosis type IVa (Morquio A syndrome) and mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome) are rare inherited lysosomal storage diseases associated with significant functional impairment and a wide spectrum of debilitating clinical manifestations. These conditions are thought to have higher-than-average prevalence rates in Saudi Arabia due to high rates of consanguineous marriage in the country. There are several unmet needs associated with the management of these diseases in Saudi Arabia.

MAIN BODY

The aim of this manuscript is to contextualize unmet management needs and provide recommendations to optimize diagnosis, multidisciplinary care delivery, and local data generation in this disease area. An expert panel was assembled comprising seven consultant geneticists from across Saudi Arabia. The Delphi methodology was used to obtain a consensus on statements relating to several aspects of mucopolysaccharidosis types IVa and VI. A consensus was reached for all statements by means of an online, anonymized voting system. The consensus statements pertain to screening and diagnosis, management approaches, including recommendations pertaining to enzyme replacement therapy, and local data generation.

CONCLUSION

The consensus statements presented provide specific recommendations to improve diagnostic and treatment approaches, promote multidisciplinary care and data sharing, and optimize the overall management of these rare inherited diseases in Saudi Arabia.

The top 100 most cited articles on mucopolysaccharidoses: a bibliometric analysis

Background: Bibliometrics can trace general research trends in a particular field. Mucopolysaccharidoses (MPS), as a group of rare genetic diseases, seriously affect the quality of life of patients and their families. Scholars have devoted themselves to studying MPS's pathogenesis and treatment modalities and have published many papers. Therefore, we conducted a bibliometric and visual study of the top 100 most highly cited articles to provide researchers with an indication of the current state of research and potential directions in the field. Methods: The Web of Science Core Collection was searched for articles on MPS from 1 January 1900, to 8 November 2023, and the top 100 most cited articles were screened. The title, year of publication, institution, country, and first author of the articles were extracted and statistically analyzed using Microsoft Excel 2007. Keyword co-occurrence and collaborative networks were analyzed using VOSviewer 1.6.16. Results: A total of 9,273 articles were retrieved, and the top 100 most cited articles were filtered out. The articles were cited 18,790 times, with an annual average of 188 citations (122-507). Forty-two journals published these articles, with Molecular Genetics and Metabolism and Proceedings of the National Academy of Sciences of the United States being the most published journal (N = 8), followed by Pediatrics (N = 7), Blood (N = 6). The United States (N = 68), the UK (N = 25), and Germany (N = 20) were the top contributing countries. The Royal Manchester Children's Hospital (N = 20) and the University of North Carolina (N = 18) were the most contributing institutions. Muenzer J was the most prolific author (N = 14). Conclusion: We conducted a bibliometric and visual analysis of the top 100 cited articles in MPS. This study identifies the most influential articles currently available in the field of MPS, which provides a good basis for a better understanding of the disease and informs future research directions.

Biomarkers of Glycosaminoglycans (GAG) accumulation in patients with mucopolysaccharidosis type VI-LeukoGAG, Corneal Opacification (COM) and Carotid Intima Media Thickening (CIMT)

Mucopolysaccharidosis type VI (MPS VI) is an autosomal recessive lysosomal storage disorder characterized by deficient activity of arylsulfatase B enzyme (ASB) resulting in cellular accumulation of dermatan sulfate (DS) and chondroitin sulfate (CS) that leads to cell injury. Urinary glycosaminoglycans (GAG) are often used as a biomarker in MPS diseases for diagnosis and to monitor treatment efficacy. This study evaluated leukocyte GAGs (leukoGAG) and skin GAGs as alternate biomarkers representing intracellular GAG changes in patients with MPS VI and treated with enzyme replacement therapy (ERT). In addition, we evaluated corneal opacification measurements (COM) and carotid intima media thickness (CIMT) as indicators of GAG accumulation and tissue injury. The study was performed in a serial two-step design in a single center. A quantitative method to measure leukoGAG levels in leukocytes was developed in Study 1 to compare the GAG levels between MPS VI patients and a control group and to assess correlations between leukoGAG and urineGAG. Study 2 validated the leukoGAG measurement, assessed the effect of ERT infusion on leukoGAG and ASB activity in leukocytes, identified correlations between leukoGAG and other biomarkers, and assessed differences in GAG accumulation between MPS VI patients and control subjects. In Study 1, leukoCS and leukoDS levels were significantly higher in the MPS VI group than the control group (leukoCS: 37.9 ± 10.2 and 2.9 ± 1.5 μg/μg protein, respectively, p = 0.005; leukoDS: 0.26 ± 0.2 and 0.0 ± 0.0 μg/μg protein, respectively, p = 0.028) with positive correlations between leukoCS and urine CS and leukoDS and urineDS. In Study 2, leukoCS (32.0 ± 11.8 vs 6.9 ± 3.1 μg/mg protein, p = 0.005) and leukoDS (0.4 ± 0.1 and 0.2 ± 0.1 μg/mg protein, p = 0.020) were significantly higher compared with control subjects. Thus, these results highlight the potential of leukoGAG as a new biomarker representing intracellular GAG accumulation in MPS VI patients and may be valuable for patient management.

The importance of skeletal x-ray screening for dysostosis multiplex in the early diagnosis of mucopolysaccharidosis

PURPOSE

Our aim is the early detection of mucopolysaccharidosis (MPS) by examining the radiographs taken for reasons other than a metabolic disease, such as infection, trauma, and short stature.

METHODS

The radiographs of children who applied to outpatient and emergency clinics in our hospital between 01/01/2022 and 31/12/2022 were examined by a pediatric radiologist retrospectively without knowledge of patient information. The MPS enzyme panel and urine glycosaminoglycan analysis were performed in patients having dysostosis multiplex on radiographs. In cases with MPS detected by enzyme and urine analysis, the definitive diagnosis was confirmed by genetic analysis.

RESULTS

Skeletal radiographs of 15.104 cases admitted to our hospital were examined (11,270 chest x-ray, 314 lumbosacral spine x-ray, 2970 hand x-ray, 253 pelvis x-ray, 162 skull x-ray, and 135 complete skeletal surveys). In 67 children, dysostosis multiplex was observed in the skeletal X-ray. Among them, seven newly diagnosed MPS cases were detected. Three cases were diagnosed with MPS type 4A, two with MPS type 6, one with MPS type 2 and one with MPS type 3B. Age at diagnosis was 46.2 ± 30.6 months (range; 20-111 months). There was a history of consanguinity in 6 (85.7%) cases.

CONCLUSION

Radiographs can provide clues for diagnosing MPS before the clinical findings become prominent in children admitted to the hospital for other complaints. Therefore, X-ray screening can be performed on children in endemic regions of MPS to search for dysostosis multiplex.

High-fidelity imaging of lysosomal enzyme through in situ ordered assembly of small molecular fluorescent probes

As an organelle in cells, lysosomes play an important role in the degradation of biological macromolecules and pathogens. To elucidate the function of lysosomes in normal or disease states, recently, various fluorescent probes have been reported for imaging lysosomal analytes. However, because of the particularity of the lysosomal environment, most of the reported lysosomal fluorescent probes suffered from a series of practical issues such as easy diffusion, low detection signal-to-background ratio and false signal. To address these issues, based on an optimized in situ ordered assembly solid-state fluorophore HDPQ, we herein put forward a new strategy for the design of lysosomal enzymes probes. As a proof concept, we synthesized a fluorescent probe HDPQ-GLU for lysosomal enzyme β-glucuronidase (GLU). Experiment results displayed that compared with general lysosomal probe, the novel lysosomal probe not only exhibited excellent anti-pH interference ability and high signal-to-noise ratio in aqueous solution, but also has excellent long-term in situ imaging ability in the living system. Using this probe, we have realized high-fidelity and long-term in situ tracking GLU in lysosomes of living cells and evaluated the dynamic changes of GLU during the growth period of zebrafish. We anticipate that the new strategy based on the novel in situ ordered assembly solid-state fluorophore HDPQ may be a potential platform for developing fluorescent probes for high-fidelity imaging of lysosomal enzymes.

Novel chorioretinal findings in two siblings with mucopolysaccharidosis type VI

PURPOSE

To describe and compare the systemic and ocular findings in two siblings with mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome), one treated with recombinant galsulfase, and one who was untreated.

METHOD

One female patient aged 33 years (case 1) who had received galsulfase enzyme replacement therapy for 11 years, and her younger male sibling by 3 years (case 2), who had declined systemic treatment, underwent clinical ophthalmic examination and retinal ocular coherence tomography. The female sibling underwent electrophysiology testing of visual function.

RESULTS

Case 1 had best corrected visual acuity right 6/4.8 and left 6/6. Case 2 had best corrected visual acuity of 6/6 in each eye. Case 1 had bilateral mild corneal haze and a clinically unremarkable posterior segment examination. Case 2 had bilateral very mild corneal haze and retinal striae on examination. Ocular coherence tomography showed choroidal folds at the maculae in both patients, more pronounced in Case 2, who also had retinal folds and epiretinal membrane. Electroretinography showed very mild involvement of the rods only in Case 1.

CONCLUSION

These two siblings with mucopolysaccharidosis type VI, one treated and one untreated, displayed variable levels of systemic, corneal, and chorioretinal involvement in their disease Further studies of choroidal changes in MPS VI may prove useful as a biomarker of ocular response to treatment outside the blood-retina barrier. Both patients have provided written consent to publish case details.

A novel approach in diagnosing multiple dentigerous cysts using CBCT illustration indicative of Mucopolysaccharidosis VI - a case report

Mucopolysaccharidosis VI is a genetic disorder affecting multiple organs with sundry clinical presentations. The main etiological factor reflects the disturbances in mucopolysaccharide metabolism leading to deposition of acid mucopolysaccharide in various tissues. The pathognomonic features of the disease include a large head, short neck, corneal opacity, open mouth associated with an enlarged tongue, enlargement of the skull, and long anteroposterior dimension with unerupted dentition, dentigerous cyst-like follicles, condylar defects, and gingival hyperplasia. An 18-year-old boy with Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI) is described in this article, emphasizing the oral manifestations and radiographic illustration of lesions in the jaws. It also emphasizes the essential role of cone-beam computed tomography to identify and analyze multicentric pathologies in the jaws.

Non-cardiac Manifestations in Adult Patients With Mucopolysaccharidosis

Mucopolysaccharidoses (MPS) are a heterogeneous group of disorders that results in the absence or deficiency of lysosomal enzymes, leading to an inappropriate storage of glycosaminoglycans (GAGs) in various tissues of the body such as bones, cartilage, heart valves, arteries, upper airways, cornea, teeth, liver and nervous system. Clinical manifestations can become progressively exacerbated with age and affect their quality of life. Developments in advanced supportive treatment options such as enzyme replacement therapy (ERT), hematopoietic stem cell transplantation (HSCT) may have improved patients' life span. Adult MPS patients require specialist clinical surveillance long-term. In many cases, in addition to the MPS-related health problems, they may develop age-related complications. Considering the complexity of their clinical manifestations and lack of guidelines on the management of adult MPS disorders, multispecialty and multidisciplinary teams' care is essential to diagnose and treat health problems that are likely to be encountered. This review presents non-cardiac clinical manifestations, their pathophysiology, management and long-term outcomes in adult MPS patients.

Oral treatment for mucopolysaccharidosis VI: Outcomes of the first phase IIa study with odiparcil

Mucopolysaccharidosis (MPS) disorders are a group of rare, progressive lysosomal storage diseases characterized by the accumulation of glycosaminoglycans (GAGs) and classified according to the deficient enzyme. Enzyme replacement therapy (ERT) of MPS VI has limited effects on ophthalmic, cardiovascular, and skeletal systems. Odiparcil is an orally available small molecule that results in the synthesis of odiparcil-linked GAGs facilitating their excretion and reducing cellular and tissue GAG accumulation. Improve MPS treatment was a Phase 2a study of the safety, pharmacokinetics/pharmacodynamics, and efficacy of two doses of odiparcil in patients with MPS VI. The core study was a 26-week, randomized, double-blind, placebo-controlled trial in patients receiving ERT and an open-label, noncomparative, single-dose cohort not receiving ERT. Patients aged ≥ 16 years receiving ERT were randomized to odiparcil 250 or 500 mg twice daily or placebo. Patients without ERT received odiparcil 500 mg twice daily. Of 20 patients enrolled, 13 (65.0%) completed the study. Odiparcil increased total urine GAGs (uGAGs), chondroitin sulfate, and dermatan sulfate concentrations. A linear increase in uGAG levels and odiparcil exposure occurred with increased odiparcil dose. Odiparcil demonstrated a good safety and tolerability profile. Individual analyses found more improvements in pain, corneal clouding, cardiac, vascular, and respiratory functions in the odiparcil groups vs placebo. This study confirmed the mechanism of action and established the safety of odiparcil with clinical beneficial effects after only a short treatment duration in an advanced stage of disease. Further assessment of odiparcil in younger patients is needed.

Fifteen years of enzyme replacement therapy for mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome): a case report

Background

Mucopolysaccharidosis VI, or Maroteaux–Lamy disease, is an autosomal recessive disease characterized by deficiency of the enzyme arylsulfatase B in the lysosomal catabolism of glycosaminoglycans. Due to reduced (or even null) enzyme activity, glycosaminoglycans (mainly dermatan sulfate) accumulates, leading to a multisystemic disease. Mucopolysaccharidosis VI induces reduced growth, coarse face, audiovisual deficits, osteoarticular deformities, and cardiorespiratory issues, hampering the quality of life of the patient. Enzyme replacement therapy with galsulfase (Naglazyme, BioMarin Pharmaceuticals Inc., USA) is the specific treatment for this condition. Although studies have shown that enzyme replacement therapy slows the progression of the disease, the effects of long-term enzyme replacement therapy remain poorly understood.

Case presentation

A 29-year-old, Caucasian, male patient diagnosed with mucopolysaccharidosis VI was treated with enzyme replacement therapy for over 15 years. Enzyme replacement therapy was initiated when patient was 13 years old. The patient evolved multiplex dysostosis, carpal tunnel syndrome, thickened mitral valve, and hearing and visual loss.

Conclusions

Although enzyme replacement therapy did not prevent the main signs of mucopolysaccharidosis VI, it slowed their progression. Additionally, enzyme replacement therapy was associated with a longer survival compared with the untreated affected sibling. Taken together, the results indicate that enzyme replacement therapy positively modified the course of the disease.

Ovarian Mucinous Carcinoma in a Pediatric Patient With Maroteaux-Lamy Syndrome

Mucopolysaccharidoses (MPS) are autosomal recessive lysosomal storage disorder (LSD). Mucinous ovarian cancer is a rare tumor and seldom encounters among adolescents. Here we describe an adolescent female with MPS type VI diagnosed with mucinous ovarian cancer. To our knowledge, this is the first case report of ovarian mucinous carcinoma in a patient with MPS. The association between MPS and cancer has never been described so far, but some LSD are known to have an increased risk of malignancies. The pathogenetic link between LSD and cancer is not well understood. Several potential mechanisms have been proposed for pathogenesis, which include chronic inflammation, abnormal function of activated macrophages, and genetic modifiers. Further studies are required, to understand the role of LSD in cancer.

Clinical and event-based outcomes of patients with mucopolysaccharidosis VI receiving enzyme replacement therapy in Turkey: a case series

Background

The objective of this study was to describe clinical manifestations and events of patients with mucopolysaccharidosis (MPS) VI in Turkey who are treated with galsulfase enzyme replacement therapy (ERT). Clinical data of 14 children with MPS VI who were followed up at the Department of Pediatrics of the Gazi University Faculty of Medicine in Ankara, Turkey were retrospectively collected from the patients’ medical records. Patients were selected based on availability of a pre-ERT baseline and follow-up clinical data for a similar period of time (1.9–3.2 years). Event data (occurrence of acute clinical events, onset of chronic events, surgeries) collected during hospital visits and telemedicine were available for up to 10 years after initiation of ERT (2.5–10 years).

Results

Age at initiation of ERT ranged from 2.8 to 15.8 years (mean age 7.5 years). All patients presented with reduced endurance and skeletal abnormalities (dysostosis multiplex) on radiography. Other common clinical manifestations were cardiac valve disease (N = 13), short stature (N = 11), cranial abnormalities on MRI (N = 10), spinal abnormalities on MRI (N = 7), and mild cognitive impairment (N = 6). School attendance was generally poor, and several patients had urinary incontinence. After 1.9 to 3.2 years of ERT, most patients showed improvements in endurance in the 6-min walk test and 3-min stair climb tests; the frequency of urinary incontinence decreased. ERT did not seem to prevent progression of cardiac valve disease, eye disorders, hearing loss, or bone disease. Long-term event-based data showed a high incidence of respiratory tract infections, adenotonsillectomy/adenoidectomy, reduced sleep quality, sleep apnea, and depression before initiation of ERT. The number of events tended to remain stable or decrease in all patients over 2.5–10 years follow-up. However, the nature of the events shifted over time, with a reduction in the frequency of respiratory tract infections and sleep problems and an increase in ophthalmologic events, ear tube insertions, and depression.

Conclusions

This case series shows the high disease burden of the MPS VI population in Turkey and provides a unique insight into their clinical journey based on real-life clinical and event-based data collected before and after initiation of ERT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-02060-4.

Enzyme replacement therapy with galsulfase for mucopolysaccharidosis type VI

BACKGROUND

Mucopolysaccharidosis type VI (MPS VI) or Maroteaux-Lamy syndrome is a rare genetic disorder caused by the deficiency of arylsulphatase B. The resultant accumulation of dermatan sulphate causes lysosomal damage. The clinical symptoms are related to skeletal dysplasia (i.e. short stature and degenerative joint disease). Other manifestations include cardiac disease, impaired pulmonary function, ophthalmological complications, hepatosplenomegaly, sinusitis, otitis, hearing loss and sleep apnea. Intellectual impairment is generally absent. Clinical manifestation is typically by two or three years of age; however, slowly progressive cases may not present until adulthood. Enzyme replacement therapy (ERT) with galsulfase is considered a new approach for treating MPS VI.

OBJECTIVES

To evaluate the effectiveness and safety of treating MPS VI by ERT with galsulfase compared to other interventions, placebo or no intervention.

SEARCH METHODS

Eletronic searches were performed on the Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register. Date of the latest search:  09 June 2021. Further searches of the following databases were also performed: CENTRAL, MEDLINE, LILACS, the Journal of Inherited Metabolic Disease, the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov. Date of the latest search: 20 August 2021.

SELECTION CRITERIA

Randomized and quasi-randomized controlled clinical studies of ERT with galsulfase compared to other interventions or placebo.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the studies, assessed the risk of bias, extracted data and assessed the certainty of the the evidence using the GRADE criteria.

MAIN RESULTS

One study was included involving 39 participants who received either ERT with galsulfase (recombinant human arylsulphatase B) or placebo. This small study was considered overall to have an unclear risk of bias in relation to the design and implementation of the study, since the authors did not report how both the allocation generation and concealment were performed. Given the very low certainty of the evidence, we are uncertain whether at 24 weeks there was a difference between groups in relation to the 12-minute walk test, mean difference (MD) of 92.00 meters (95% confidence interval (CI) 11.00 to 172.00), or the three-minute stair climb, MD 5.70 (95% CI -0.10 to 11.50). In relation to respiratory tests, we are uncertain whether galsulfase makes any difference as compared to placebo in forced vital capacity in litres (FVC (L) (absolute change in baseline), given the very low certainty of the evidence. Cardiac function was not reported in the included study. We found that galsulfase, as compared to placebo, may decrease urinary glycosaminoglycan levels at 24 weeks, MD -227.00 (95% CI -264.00 to -190.00) (low-certainty evidence). We are uncertain whether there are differences between the galsulfase and placebo groups in relation to adverse events (very low-certainty evidence). In general, the dose of galsulfase was well tolerated and there were no differences between groups. These events include drug-related adverse events, serious and severe adverse events, those during infusion, drug-related adverse events during infusion, and deaths. More infusion-related reactions were observed in the galsulfase group and were managed with interruption or slowing of infusion rate or administration of antihistamines or corticosteroids drugs. No deaths occurred during the study.   AUTHORS' CONCLUSIONS: The results of this review are based only on one small study (a 24-week randomised phase of the study and prior to the open-label extension). We are uncertain whether galsulfase is more effective than placebo, for treating people with MPS VI, in relation to the 12-minute walk test or the three-minute stair climb, as the certainty of the evidence has been assessed as very low. We found that galsulfase may reduce urinary glycosaminoglycans levels. We are also uncertain whether there are any differences between treatment groups in relation to cardiac or pulmonary functions, liver or spleen volume, overnight apnea-hypopnea, height and weight, quality of life and adverse effects. Further studies are needed to obtain more information on the long-term effectiveness and safety of ERT with galsulfase.

Gene Therapy for Neuronopathic Mucopolysaccharidoses: State of the Art

The need for long-lasting and transformative therapies for mucopolysaccharidoses (MPS) cannot be understated. Currently, many forms of MPS lack a specific treatment and in other cases available therapies, such as enzyme replacement therapy (ERT), do not reach important areas such as the central nervous system (CNS). The advent of newborn screening procedures represents a major step forward in early identification and treatment of individuals with MPS. However, the treatment of brain disease in neuronopathic MPS has been a major challenge to date, mainly because the blood brain barrier (BBB) prevents penetration of the brain by large molecules, including enzymes. Over the last years several novel experimental therapies for neuronopathic MPS have been investigated. Gene therapy and gene editing constitute potentially curative treatments. However, despite recent progress in the field, several considerations should be taken into account. This review focuses on the state of the art of in vivo and ex vivo gene therapy-based approaches targeting the CNS in neuronopathic MPS, discusses clinical trials conducted to date, and provides a vision for the future implications of these therapies for the medical community. Recent advances in the field, as well as limitations relating to efficacy, potential toxicity, and immunogenicity, are also discussed.

Mucopolysaccharidoses diagnosis in the era of enzyme replacement therapy in Egypt

BACKGROUND

Undegraded glycosaminoglycans (GAGs) induced by deficiency of enzymes are the primary cause of mucopolyscchardoses. Mucopolysacchardoses (MPS) are a group of rare lysosomal storage diseases (LSD). The quantification of a specific enzymatic activity is needed for accurate diagnosis. The objectives of this work were: first, to continue the study of mucopolysacchardoses disease in Egypt after the start of using the enzyme replacement therapy (ERT). Second, to define the commonest types among our population after 18 years experience with the disease. Third, to compare the different MPS types' distribution, diagnosed after the start of the ERT, to identify the impact of using ERT on the number and type of diagnosed patients.

METHOD

Urinary GAGs were measured for all referred cases followed by two-dimensional electrophoretic separation for cases with high levels of GAGs; the specific enzyme activity was assayed for each type depending on the abnormal electrophoretic pattern obtained. Clinically suspected cases of Morquio syndrome were directly subjected to measuring the specific enzyme.

RESULTS

Out of 1448 suspected cases, 622 (42.9%) MPS patients were diagnosed revealing the following distribution: MPS I (172, 27.7%), MPS II (57, 9.1%), MPS III [(177, 28.5%: 134 type B and 43 types A, C or D)], MPS IVA (124, 19.9%), MPS VI (90, 14.5%) and MPS VII (2, 0.3%). MPS III was the most commonly diagnosed type followed by MPS I and MPS IVA. MPS IVA represented the most common type receiving treatment, followed by MPS I, MPS II and MPS VI.

CONCLUSION

The presence of treatment encouraged the affected families and physicians to seek diagnosis. MPS III was the commonest type among our studied group after 7 years of diagnosis, while MPS IVA was the commonest type receiving treatment.

Sensory, voluntary, and motor postural control in children and adolescents with mucopolysaccharidosis

OBJECTIVES

This study aimed to investigate automatic and voluntary motor control performances, which have an important function in maintaining balance, in children and adolescents with mucopolysaccharidosis (MPS).

METHODS

The records of 70 patients were retrospectively analyzed. The results of Computerized Dynamic Posturography (CDP) performed according to the age and development of the individuals were examined. The results of 10 children and adolescents with MPS (mean age: 9.43 ranging from 6 to 14; four males and six females) who completed the sensory analysis, Weight-Bearing Squat Test, and Adaptation Test were retrieved from the database of the CDP. Nine healthy children and adolescents with typical development (mean age: 9.63 ranging from 6 to 14; four males and five females) were included as the control group.

RESULTS

In the sensory analysis test, there was a statistically significant difference between the two groups in the visual ratio parameter. In the adaptation test, there was a statistically significant difference between the two groups in the toes up and toes down trials. There was no statistically significant difference between the groups in the Weight-Bearing Squat test at 0° knee extension and various knee flexions.

CONCLUSIONS

Children and adolescents with MPS should be directed to the appropriate exercise and therapy programs to develop postural and balance control, which have a significant effect on their quality of life and the ability to independently perform daily activities of living. In addition to routine hearing assessments for patients with MPS, other objective tests used in the differential diagnosis of balance and vestibular system should also be implemented.

Otorhinolaryngological Management in Taiwanese Patients with Mucopolysaccharidoses

Background: Mucopolysaccharidoses (MPSs) are lysosomal storage disorders wherein glycosaminoglycans accumulate because the enzymes that degrade them are insufficient. The earliest symptoms, which are the main reasons for seeking consultation, are otorhinolaryngological and commonly occur in MPS I, II, IV, and VI. This retrospective study aimed to determine the occurrence of otorhinolaryngological manifestations in MPS patients in Taiwan and to analyze the prognosis of surgical intervention, including its effect on symptoms. Methods: We reviewed 42 patients (30 males and 12 females), with a median age of 20.5 years, who had MPS (16.7% type I, 35.7% type II, 19.0% type IIIB, 21.4% type IVA, and 7.2% type VI). The following otorhinolaryngological manifestations were collected: annual number of upper respiratory tract infections (URTIs) and otitis media with effusion (OME) episodes, adenoid size, tonsillar size, and apnea-hypopnea index (AHI). Results: Among 42 patients, we found recurrent otitis media in 42.9% of the patients, hearing loss in 83.3% (mixed: 52.4%, conductive: 21.4%, and sensorineural: 9.5%), frequent URTIs in 47.6%, and obstructive sleep apnea syndrome in 35.7%. Moreover, 76% of the patients underwent ear, nose, and throat (ENT) surgery, including adenoidectomy, tonsillectomy, tympanostomy with ventilation tube insertion, tracheotomy, and supraglottoplasty. Conclusions: MPS patients had a high incidence of ENT problems. ENT surgery reduced the severity of hearing loss, degree of symptoms related to upper airway obstruction, and severity of respiratory tract and otological infections of patients with MPS.

A Generic Assay to Detect Aberrant ARSB Splicing and mRNA Degradation for the Molecular Diagnosis of MPS VI

Identification and characterization of disease-associated variants in monogenic disorders is an important aspect of diagnosis, genetic counseling, prediction of disease severity, and development of therapy. However, the effects of disease-associated variants on pre-mRNA splicing and mRNA degradation are difficult to predict and often missed. Here we present a generic assay for unbiased identification and quantification of arylsulfatase B (ARSB) mRNA for molecular diagnosis of patients with mucopolysaccharidosis VI (MPS VI). We found that healthy control individuals have inefficient ARSB splicing because of natural skipping of exon 5 and inclusion of two pseudoexons in introns 5 and 6. Analyses of 12 MPS VI patients with 10 different genotypes resulted in identification of a 151-bp intron inclusion caused by the c.1142+2T>C variant and detection of low ARSB expression from alleles with the c.629A>G variant. A special case showed skipping of exon 4 and low ARSB expression. Although no disease-associated DNA variant could be identified in this patient, the molecular diagnosis could be made based on RNA. These results highlight the relevance of RNA-based analyses to establish a molecular diagnosis of MPS VI. We speculate that inefficient natural splicing of ARSB may be a target for therapy based on promotion of canonical splicing.

Home treatment of type VI mucopolysaccharidosis (Maroteaux-Lamy syndrome) an alternative at this time of COVID-19 pandemic: A case in Peru

We report a patient with mucopolysaccharidosis type VI, on long-term enzyme replacement home therapy. Results support the efficacy and safety benefits, with additional advantage of home therapy to minimize the risk of community-transmitted infections.

A case of mucopolysaccharidosis type VI in a polish family. Importance of genetic testing and genotype-phenotype relationship in the diagnosis of mucopolysaccharidosis

Background and objectives

Mucopolysaccharidosis type VI (MPS VI) is a rare, autosomal recessive lysosomal storage disorder caused by deficient enzymatic activity of N-acetyl galactosamine-4-sulphatase, which is caused by mutations in the arylsulphatase B (ARSB) gene. To date, 163 different types of mutations in the ARSB have been reported. However, the full mutation spectrum in the MPS VI phenotype is still not known. The aim of this study was to perform molecular testing of the ARSB gene in the patient and his family members to confirm MPS VI.

Methods

Molecular characterisation of the ARSB gene was performed using Sanger sequencing. We studied a child suspected of having MPS VI and 16 other relatives.

Results

We identified a C-to-T transition resulting in an exchange of the Arg codon 160 for a premature stop codon (R160*, in exon 2). The transition was in CpG dinucleotides.

Interpretation and conclusions

The study provided some insights into the genotype-phenotype relationship in MPS VI and the importance of genetic testing when diagnosing MPS, which is not a mandatory test for the diagnosis and only very occasionally performed. Additionally, we present here the history of a family with confirmed MPS VI, which is extremely rare especially in south-eastern Poland. What is more, the position where the mutation is located is very interesting because it is the region of CpG, which is the site of the methylation process. Thus, this opens the possibility of a new approach indicating the involvement of an epigenetic mechanism that should be examined in the context of the pathomechanism of MPS.

Improvement in functional gait parameters following corrective thoracolumbar surgery in children affected by Mucopolysaccharidosis 1 (Hurler syndrome)

OBJECTIVE

Thoracolumbar kyphosis is a common indication for spinal surgery in children with Mucopolysaccharidosis. Functional outcome of spinal surgical intervention has never been published in patients with this rare disease. We present a cohort of patients with Mucopolysaccharidosis 1(Hurler syndrome) who underwent thoraco-lumbar spinal deformity correction and functional outcome assessed by pre-operative and post-operative gait analysis. This study represents the first attempt at presenting a functional assessment of surgical outcome in any Mucopolysaccharidosis subtype.

METHODS

A retrospective analysis of prospectively collected data was carried out from 11 children diagnosed with this subtype of Mucopolysaccharidosis. All patients underwent thoracolumbar kyphosis correction between the years 2013 to 2016. Gait assessment was performed using GAITRite™ electronic walkway pre-operatively and post-operatively within 9 to 24 months from the index surgery. Walking distance, cadence and gait velocity were the three spatio-temporal parameters analysed. Wilcoxon signed rank test was used to analyse the data and P-Value ≤0.05 was deemed significant.

RESULTS

There was a statistically significant improvement in walking distance in 9 out of 11 patient post-operatively with a mean increase of 232.06 cms (P = 0.05). There was marginal improvement in cadence by 6.33 steps/min post-operatively (P-value 0.79). Gait velocity also showed a marginal increase by 8.73 cms/sec post-operatively (P-value 0.32).

CONCLUSION

The results of our study suggest that correction of thoracolumbar kyphosis in children with Mucopolysaccharidosis 1 resulted in a significant improvement of walking distance with a trend towards improved gait in the other parameters. Post-operative change in cadence was not statistically significant suggesting that physiological maturation of gait had minimal effect in the specified post-operative assessment timeframe. This study emphasizes that outcomes of spinal surgery in children with Mucopolysaccharidosis 1 should be determined by functional measures aiming to maintain or improve quality of life.

Critical clinical situations in adult patients with Mucopolysaccharidoses (MPS)

Background

Mucopolysaccharidoses (MPS) are rare, inherited disorders associated with enzyme deficiencies that result in glycosaminoglycan (GAG) accumulation in multiple organ systems. Management of MPS is evolving as patients increasingly survive to adulthood and undergo multiple surgeries throughout their lives. As surgeries in these patients are considered to be high risk, this can result in a range of critical clinical situations in adult patients.

Results

We discuss strategies to prepare for and manage critical clinical situations in adult patients with MPS, including supporting the multidisciplinary team, preoperative and airway assessments, surgical preparations, and postoperative care. We also present eight critical clinical cases (age range: 21–38 years) from four leading inherited metabolic disease centres in Europe to highlight challenges and practical solutions to optimise the care of adult patients with MPS. Critical clinical situations included surgical procedures, pregnancy and a thrombus in a port-a-cath.

Conclusions

Individualised strategies to manage critical clinical situations need to be developed for each patient to compensate for the heterogeneous symptoms that may be present and the potential complications that may occur. These strategies should include input from the wider MDT, and be coordinated by metabolic specialists with expertise in the management of MPS disorders and surgery in adult patients with MPS.

Anterior Chamber Angles in Different Types of Mucopolysaccharidoses

PURPOSE

To evaluate the anterior chamber angle status and estimate the intraocular pressure (IOP) in patients with mucopolysaccharidoses (MPSs) type I, II, IV, and VI.

DESIGN

Prospective cross-sectional study.

METHODS

This study enrolled 27 consecutive MPS patients (8 patients with MPS I, 4 patients with MPS II, 9 patients with MPS IV, and 6 patients with MPS VI) and 20 normal control subjects. Anterior chamber angle status was evaluated by swept-source optical coherence tomography and IOP was estimated by the new-generation tonometer Corvis ST.

RESULTS

Twelve eyes (6 patients) of 15 eyes (8 patients) with MPS I had narrow angles or peripheral iridocorneal touches together with elevated IOP (80%). Six eyes (3 patients) of 8 eyes (4 patients) with MPS II had plateau iris configuration, but all 8 eyes had normal IOP. All 18 eyes (9 patients) with MPS IV had normal angle structures, but 8 eyes (4 patients) had elevated IOP (44.4%). Nine eyes (5 patients) of 11 eyes (6 patients) with MPS VI had shallow but not closed angles (81.8%). Among these 9 eyes, 5 eyes had elevated IOP, and 4 of these 5 eyes had IOP >30 mm Hg. The trabecular iris angles of MPS types I, II, and VI were smaller than those of MPS type IV and of the control subjects. The angle recess areas of MPS types I and VI were smaller than those of MPS type IV and of the control subjects.

CONCLUSIONS

MPS type I patients are prone to have glaucoma with narrow or closed angles; MPS type II patients tend to have plateau iris; MPS type IV patients are vulnerable to open-angle glaucoma; MPS type VI patients have narrow angles not as close as those of MPS type I. MPS types I, IV, and VI had higher IOP estimates than the control subjects, but only MPS I and IV had higher corrected IOP estimates than the control subjects. The ordinary IOP estimates in MPS VI patients may be falsely high because of clouded corneas and increased corneal rigidity. Swept-source optical coherence tomography helps ophthalmologist investigate the angle structure and the pathophysiology of glaucoma caused by MPS.

Mucopolysaccharidosis type VI: case report with first neonatal presentation with ascites fetalis and rapidly progressive cardiac manifestation

BACKGROUND

The Mucopolysaccharidosis type VI (MPS VI), also known as Maroteaux-Lamy syndrome (OMIM 253200) is an autosomal recessive lysosomal disorder, caused by the deficiency of the enzyme N-acetylgalactosamine 4-sulfatase (also known as arylsulfatase B) due to mutations of the ARSB gene. Cardiologic features are well recognized, and are always present in MPS VI patients. Generally, the onset and the progression of the cardiologic symptoms are insidious, and just a few patients have developed a rapidly progressive disease. Cardiac involvement in MPS VI is a common and progressive feature. For MPS patients, cardiac evaluations are recommended every 1 to 2 years, including blood pressure measurement, electrocardiography and echocardiography. However, congestive heart failure and valvular surgical repair are not frequently seen, and if so, they are performed in adults. Here we report on an atypical MPS VI case with ascites fetalis and a rapidly progressive cardiac disease.

CASE PRESENTATION

A 6-month-old Brazilian male, only child of a Brazilian healthy non-consanguineous couple. During pregnancy, second trimester ultrasonography observed fetal ascites and bilateral hydrocele. Physical exam at 6 months-old revealed a typical gibbus deformity and MPS was suspected. Biochemical investigation revealed a diagnosis of MPS type VI, confirmed by molecular test. Baseline echocardiogram revealed discrete tricuspid regurgitation and a thickened mitral valve with posterior leaflet prolapse, causing moderate to severe regurgitation. The patient evolved with mitral insufficiency and congestive heart failure, eventually requiring surgical repair by the first year of age.

CONCLUSIONS

We report the first case of MPS VI whose manifestations started in the prenatal period with fetal ascites, with severe cardiac valvular disease that eventually required early surgical repair. Moreover, in MPS with neonatal presentation, including fetal hydrops, besides MPS I, IVA and VII, clinicians should include MPS VI in the differential diagnosis.

[Navigating in rare oceans: notes from a family survey of children and adolescents living with rare diseases]

This article seeks to highlight the construction of social navigation in a hospital. Our focus is to reflect on scenes of application of a questionnaire on family costs of care/treatment of children with rare diseases. These processes are linked to the markers of gender, race, and generation of one of the authors. The interaction between researcher and subjects of field research is socially constructed according to the specific circumstances that demarcate the invitation to participate in the research, as well as data collection. It implies that his position as a researcher and the ethical perspective need to be well defined. The approach and ethics build this social navigation with the hospital and the subjects are permeated by difficulty and uncertainty, but also by surprises and learning. It was possible to observe remarkable characteristics of the institution, of their employees and the families, to evaluate the used methodological strategies.

Transition of patients with mucopolysaccharidosis from paediatric to adult care

Mucopolysaccharidoses (MPS) are rare disorders associated with enzyme deficiencies, resulting in glycosaminoglycan (GAG) accumulation in multiple organ systems. As patients increasingly survive to adulthood, the need for a smooth transition into adult care is essential. Using case studies, we outline strategies and highlight the challenges of transition, illustrating practical solutions that may be used to optimise the transition process for patients with MPS disorders.

Seven MPS case studies were provided by four European inherited metabolic disease centres; six of these patients transferred to an adult care setting and the final patient remained under paediatric care. Of the patients who transferred, age at the start of transition ranged between 14 and 18 years (age at transfer ranged from 16 to 19 years).

While there were some shared features of transition strategies, they varied in duration, the healthcare professionals involved and the management of adult patients with MPS. Challenges included complex symptoms, patients' unwillingness to attend appointments with unfamiliar team members and attachment to paediatricians. Challenges were resolved by starting transition at an early age, educating patients and families, and providing regular communication with and reassurance to the patient and family. Sufficient time should be provided to allow patients to understand their responsibilities in the adult care setting while feeling assured of continued support from healthcare professionals. The involvement of a coordinated multidisciplinary team with expertise in MPS is also key. Overall, transition strategies must be comprehensive and individualised to patients' needs.

Enzyme replacement therapy initiated in adulthood: Findings from the mucopolysaccharidosis VI Clinical Surveillance Program

OBJECTIVE

To evaluate the impact of galsulfase enzyme replacement therapy (ERT) when initiated in adulthood for patients with mucopolysaccharidosis (MPS) VI.

METHODS

In 2005, the multi-national, MPS VI Clinical Surveillance Program (CSP) was established to collect long-term observational data from routine clinical and laboratory assessments. A sub-analysis was performed in patients who started ERT at ≥16 years of age and had received galsulfase for ≥6 months. Urinary glycosaminoglycans (uGAG), 6-min walk test (6MWT), 3-min stair climb test (3MSCT), pulmonary function measures, cardiac function, ophthalmology measures, liver and spleen sizes, and safety were evaluated.

RESULTS

Of 223 patients enrolled in the CSP, 51 were included in the sub-analysis. Patients were between 16 and 63 years of age at first infusion. From pre-treatment baseline, uGAG level decreased by a mean (±standard deviation [SD]) of 66 (±45)% (N = 29) after a median follow-up of 7.2 years. 6MWT distance decreased slightly by a mean of 17 (±107) meters (N = 23) after 6.6 years. Stairs/min in the 3MSCT increased by a mean of 26 (±33) (N = 14) after 2.8 years. Pulmonary function measures, forced expiratory volume in 1 second and forced vital capacity, increased by a mean of 0.06 (±0.21) L after 7.3 years and 0.05 (±0.28) L after 7.2 years, respectively (N = 19 for both measures). Overall, galsulfase was well tolerated, with most adverse events reported being MPS-related clinical manifestations and not related to galsulfase.

CONCLUSIONS

Results of this sub-analysis of the CSP suggest that initiation of galsulfase in adulthood is well tolerated and can possibly stabilize MPS VI in the long term.

Recommendations for the management of MPS VI: systematic evidence- and consensus-based guidance

Introduction

Mucopolysaccharidosis (MPS) VI or Maroteaux-Lamy syndrome (253200) is an autosomal recessive lysosomal storage disorder caused by deficiency in N-acetylgalactosamine-4-sulfatase (arylsulfatase B). The heterogeneity and progressive nature of MPS VI necessitates a multidisciplinary team approach and there is a need for robust guidance to achieve optimal management. This programme was convened to develop evidence-based, expert-agreed recommendations for the general principles of management, routine monitoring requirements and the use of medical and surgical interventions in patients with MPS VI.

Methods

26 international healthcare professionals from various disciplines, all with expertise in managing MPS VI, and three patient advocates formed the Steering Committee group (SC) and contributed to the development of this guidance. Members from six Patient Advocacy Groups (PAGs) acted as advisors and attended interviews to ensure representation of the patient perspective. A modified-Delphi methodology was used to demonstrate consensus among a wider group of healthcare professionals with expertise and experience managing patients with MPS VI and the manuscript has been evaluated against the validated Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument by three independent reviewers.

Results

A total of 93 guidance statements were developed covering five domains: (1) general management principles; (2) recommended routine monitoring and assessments; (3) enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT); (4) interventions to support respiratory and sleep disorders; (5) anaesthetics and surgical interventions. Consensus was reached on all statements after two rounds of voting. The greatest challenges faced by patients as relayed by consultation with PAGs were deficits in endurance, dexterity, hearing, vision and respiratory function. The overall guideline AGREE II assessment score obtained for the development of the guidance was 5.3/7 (where 1 represents the lowest quality and 7 represents the highest quality of guidance).

Conclusion

This manuscript provides evidence- and consensus-based recommendations for the management of patients with MPS VI and is for use by healthcare professionals that manage the holistic care of patients with the intention to improve clinical- and patient-reported outcomes and enhance patient quality of life. It is recognised that the guidance provided represents a point in time and further research is required to address current knowledge and evidence gaps.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1080-y) contains supplementary material, which is available to authorized users.

Enzyme replacement therapy outcomes across the disease spectrum: Findings from the mucopolysaccharidosis VI Clinical Surveillance Program

The impact of galsulfase enzyme replacement therapy in patients with mucopolysaccharidosis (MPS) VI with phenotypes at either end of the disease spectrum was evaluated. The MPS VI Clinical Surveillance Program (CSP) was established to collect long-term observational data from routine clinical and laboratory assessments. A subanalysis of the CSP was performed in patients with pretreatment urinary glycosaminoglycan (uGAG) levels <100 μg/mg and ≥200 μg/mg creatinine (low- and high-uGAG) who had received galsulfase for ≥6 months. uGAG, 6-minute walk test (6MWT), 3-minute stair climb test (3MSCT), pulmonary function measures, height/growth, cardiac function, and safety were evaluated. Patients with a high-uGAG level at pre-treatment baseline (N = 68) showed greater impairments in endurance and pulmonary function than those with low-baseline uGAG levels (N = 39). From pre-treatment baseline, the distance walked on the 6MWT in the low- and high-uGAG groups increased by a mean (±SD) of 49 (±151) meters and 42 (±165) meters (median follow-up 5.5 and 7.7 years), respectively. The number of stairs/min climbed in the 3MSCT in the low- and high-uGAG groups increased by a mean of 18 (±33) and 30 (±45) (median follow-up 2.8 and 3.5 years), respectively. Overall, pulmonary function remained unchanged for both groups. No impact was seen on cardiac function. Galsulfase was generally well tolerated in both groups, with most adverse events being MPS-related complications unrelated to galsulfase. Results of this CSP sub-analysis suggest that galsulfase stabilizes MPS VI in the long-term and has an acceptable safety profile, regardless of baseline disease severity.

Neurogenic Claudication: a Review of Current Understanding and Treatment Options

PURPOSE OF REVIEW

With an aging population and increased prevalence of the disease, we set out to evaluate the validity of current diagnostic criteria for neurogenic claudication as well as the efficacy of the treatment options for the main cause, lumbar spinal stenosis (LSS).

RECENT FINDINGS

Epidural steroid injections (ESI) were most efficacious when the injectate is a steroid combined with lidocaine or lidocaine only. There are promising results regarding the efficacy of the minimally invasive lumbar decompression (MILD) procedure as well as interspinous process spacers (IPS) compared to surgical alternatives. Spinal cord stimulators are gaining ground as an effective alternative to surgery in patients with lumbar spinal stenosis that is not responsive to conservative measures or epidural injections. We found that there continues to be a lack of consensus on the diagnostic criteria, management, and treatment options for patients with LSS. The Delphi consensus is the most current recommendation to assist clinicians with making the diagnosis. Physical therapy, NSAIDs, gabapentin, and other conservative therapy measures are unproven in providing long-lasting relief. In patients with radicular symptoms, an ESI may be indicated when a combination of lidocaine with steroids is used or using lidocaine alone. In addition, there is not enough high-quality evidence to make a recommendation regarding the use of MILD versus interspinous spacers for neurogenic claudication. There remains a need for high-quality evidence regarding the efficacy of different conservative treatments, interventional procedures, and surgical outcomes in patients with neurogenic claudication in LSS.

Critical review of current MPS guidelines and management

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders that impair degradation of glycosaminoglycans (GAG). The specific GAGs that accumulate depend on the type of MPS, leading to unique characteristic clinical features. Development of guidelines for treatment of MPS has traditionally been multifaceted and largely based on palliative care. In the last three decades, hematopoietic stem cell transplantation and enzyme replacement therapy have been developed based on experimental and clinical studies. Guidelines have been established with the accumulation of the clinical data from natural history of the disease and therapeutic consequences, mainly sponsored by pharmaceutical companies. In recent years, committees in three countries, Australia (2015), Japan (2017), and Brazil (2018) have adopted guidelines for the treatment of MPS II, sponsored and authorized by each government. As novel treatments for MPS including substrate reduction therapy, pharmacological chaperone therapy, and gene therapy become clinically available, it is increasingly necessary to establish the optimal guideline for each type of MPS, considering multiple factors including therapeutic efficacy, adverse effects, age, disease stage, prognosis, feasibility and availability of access to treatment, and cost- performance. In this article, we discuss the historical guidelines for specific MPS types and the most recently adopted guidelines for MPS II and propose the development of future guidelines without conflict of interest and bias leading to mutual benefits to all parties including patients and families, professionals, tax payers, and governments.

Dental-craniofacial manifestation and treatment of rare diseases

Rare diseases are usually genetic, chronic and incurable disorders with a relatively low incidence. Developments in the diagnosis and management of rare diseases have been relatively slow due to a lack of sufficient profit motivation and market to attract research by companies. However, due to the attention of government and society as well as economic development, rare diseases have been gradually become an increasing concern. As several dental-craniofacial manifestations are associated with rare diseases, we summarize them in this study to help dentists and oral maxillofacial surgeons provide an early diagnosis and subsequent management for patients with these rare diseases.

Hematopoietic Stem Cell Transplantation for Mucopolysaccharidoses: Past, Present, and Future

Allogenic hematopoietic stem cell transplantation (HSCT) has proven to be a viable treatment option for a selected group of patients with mucopolysaccharidoses (MPS), including those with MPS types I, II, IVA, VI, and VII. Early diagnosis and timely referral to an expert in MPS are critical, followed by a complete examination and evaluation by a multidisciplinary team, including a transplantation physician. Treatment recommendations for MPS are based on multiple biological, sociological, and financial factors, including type of MPS, clinical severity, prognosis, present clinical signs and symptoms (disease stage), age at onset, rate of progression, family factors and expectations, financial burden, feasibility, availability, risks and benefits of available therapies such as HSCT, enzyme replacement therapy (ERT), surgical interventions, and other supportive care. International collaboration and data review are critical to evaluating the therapeutic efficacy and adverse effects of HSCT for MPS. Collaborative efforts to assess HSCT for MPS have been ongoing since the first attempt at HSCT in a patient with MPS reported in 1981. The accumulation of data since then has made it possible to identify early outcomes (ie, transplantation outcomes) and long-term disease-specific outcomes resulting from HSCT. The recent identification of predictive factors and the development of innovative regimens have significantly improved the outcomes of both engraftment failure and transplantation-related mortality. Assessment of long-term outcomes has considered a variety of factors, including type of MPS, type of graft, age at transplantation, and stage of disease progression, among others. Studies on long-term outcomes are considered a key factor in the use of HSCT in patients with MPS. These studies have shown the effects and limitations of HSCT on improving disease manifestations and quality of life. In this review, we summarize the efficacy, side effects, risks, and cost of HSCT for each type of MPS.

Diagnosis of Attenuated Mucopolysaccharidosis VI: Clinical, Biochemical, and Genetic Pitfalls

Mucopolysaccharidosis type VI (MPS VI) is a clinically heterogeneous lysosomal disease, which can be divided into 2 main categories on the basis of age of onset and severity of symptoms. The diagnosis of the attenuated form is often delayed given subtle facial features rather than the typical coarse facial features of the classic form. Here, we discuss the difficulties in establishing the diagnosis of MPS VI on the basis of the report of 4 individuals. The most common signs and symptoms in our series were bone abnormalities and hip pain as initial manifestations and cardiac changes detected after follow-up studies. On the basis of our cohort and others worldwide, awareness of attenuated forms of MPS VI should be increased particularly among general practitioners, pediatricians, rheumatologists, orthopedists, ophthalmologists, and cardiologists. Moreover, these health care providers should be aware of the technical aspects involved in the molecular and biochemical diagnosis process so that they are aware how diagnostic errors may occur.

Diagnosis of Mucopolysaccharidosis Based on History and Clinical Features: Evidence from the Bajio Region of Mexico

Introduction Mucopolysaccharidosis (MPS) are infrequent deposit diseases; generally, the diagnosis is delayed until symptoms appear. Age or presentation is related to the severity of the disease. A substantial number of patients are misdiagnosed since they describe nonspecific initial symptoms and signs in common. The aim of this study is to describe the common characteristics of patients with mucopolysaccharidosis already diagnosed, treated in hospitals of the Guanajuato Health System, with a special focus on early manifestations in order to review early clinical suspect manifestations. Methods A multicenter, descriptive, observational study was conducted to evaluate the cases of mucopolysaccharidosis treated and diagnosed. The study was carried out in the Pediatric departments of five big important hospitals of Bajio Mexico region in the period from February to August 2016. Results Eighteen patients were identified, 13 men and five women, with an average age of 8.6 years. The most frequent mucopolysaccharidosis was type IV A (Morquio) in seven patients, followed by type I (Hurler) in four patients, three patients for type III (San Filippo), two patients for type II (Hunter), and two patients for type VI (Maroteaux-Lamie). The commonest clinical manifestations at diagnosis were dimorphism, triangular dorsal hump, skeletal alterations (genu valgus, short stature, and flat feet), and a limited range of movement in the major joints. Non-skeletal manifestations, such as an umbilical/inguinal hernia and hepato-splenomegaly, were very frequent. In a majority of patients with mucopolysaccharidosis, the radiological data of the disease were found: they were most severe in type IV and type VI, mild in type I and II, and none in MPS III. A diagnosis was made in all patients by a clinical and radiological evaluation and confirmed by an enzymatic study. Conclusions In all rare diseases, a suspicion diagnosis is based on subtle characteristics that manifest themselves in a few different organs and systems may be mild. Suspicion by the physician and the need to strengthen collaboration patterns between different specialities play an important role in the early diagnosis and treatment of these conditions.

ENT and mucopolysaccharidoses

The mucopolysaccharidoses (MPS) are a heterogeneous group of inherited metabolic disorders, each associated with a deficiency in one of the enzymes involved in glycosaminoglycan (GAG) catabolism. Over time, GAGs accumulate in cells and tissues causing progressive damage, a variety of multi-organ clinical manifestations, and premature death. Ear, nose, and throat (ENT) disorders affect more than 90% of MPS patients and appear in the early stage of MPS; also reported are recurrent otitis media and persistent otitis media with effusion, macroglossia, adenotonsillar hypertrophy, nasal obstruction, obstructive sleep apnoea syndrome (OSAS), hearing loss, and progressive respiratory disorders. Undiagnosed MPS patients are frequently referred to otolaryngologists before the diagnosis of MPS is confirmed. Otolaryngologists thus have an early opportunity to recognize MPS and they can play an increasingly integral role in the multidisciplinary approach to the diagnosis and management of many children with MPS. The ENT commitment is therefore to suspect MPS when non-specific ENT pathologies are associated with repeated surgical treatments, unexplainable worsening of diseases despite correct treatment, and with signs, symptoms, and pathological conditions such as hepatomegaly, inguinal hernia, macrocephaly, macroglossia, coarse facial features, hydrocephalous, joint stiffness, bone deformities, valvular cardiomyopathy, carpal tunnel syndrome, and posture and visual disorders.

Family study of a novel mutation of mucopolysaccharidosis type VI with a severe phenotype and good response to enzymatic replacement therapy: Case report

RATIONALE

Mucopolysaccharidosis type VI (MPS VI) or Maroteaux-Lamy syndrome is produced by the deficiency of the enzyme arylsulfatase B, responsible for the hydrolysis of N-acetyl-D-galactosamine, chondroitin sulfate, and dermatan sulfate.

PATIENT CONCERNS

A 3-year-old male with Moroccan origins is the index case. He had healthy consanguineous parents and 4 healthy brothers and sisters. The patient showed a wide spectrum of symptoms including skeletal dysplasia and short stature with elevated glycosaminoglycans (GAGs) in urine.

DIAGNOSES, INTERVENTIONS, AND OUTCOMES

GAGs were quantified by spectrometry method with 1,9-dimethylen blue in 24-hour urine samples. The qualitative analysis of urine GAGs was obtained by thin-layer chromatography to determine the predominant presence of dermatan sulfate. The activities of both arylsulfatase B and beta-galactosidase as well as genetic studies were performed in dried blood spots. The genetic study was performed with deoxyribonucleic acid by massive sequencing a of lisosomal storage diseases. Results showed a new mutation c.263A > C with the severe phenotype in homozygous in the patient. The familiar study of ARSB and GLB1 genes presented some asymptomatic SNPs but with a discrete decrease in the activity of arylsulfatase B and beta-galactosidase. After an early detection by pediatricians, and both enzymatic and genetic confirmation, the patient had a good response to substitutive enzymatic treatment with galsulfase.

LESSONS

Mucoplysaccharidosis type VI is an autosomal recessive rare disease characterized by a lysosomal storage disorder. Although a number of mutations have been already associated to the disease, we have found a new mutation located in the arylsulfatase B enzyme gene. We have described that this mutation is the ultimate cause of a severe presentation of the disease.

Molecular genetics and metabolism, special edition: Diagnosis, diagnosis and prognosis of Mucopolysaccharidosis IVA

Mucopolysaccharidosis IVA (MPS IVA, Morquio A syndrome) is an autosomal recessive disorder caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase. Deficiency of this enzyme leads to the accumulation of specific glycosaminoglycans (GAGs), chondroitin-6-sulfate (C6S) and keratan sulfate (KS), which are mainly synthesized in the cartilage. Therefore, the substrates are stored primarily in the cartilage and its extracellular matrix (ECM), leading to a direct impact on bone development and successive systemic skeletal spondylepiphyseal dysplasia. The skeletal-related symptoms for MPS IVA include short stature with short neck and trunk, odontoid hypoplasia, spinal cord compression, tracheal obstruction, obstructive airway, pectus carinatum, restrictive lung, kyphoscoliosis, platyspondyly, coxa valga, genu valgum, waddling gait, and laxity of joints. The degree of imbalance of growth in bone and other organs and tissues largely contributes to unique skeletal dysplasia and clinical severity. Diagnosis of MPS IVA needs clinical, radiographic, and laboratory testing to make a complete conclusion. To diagnose MPS IVA, total urinary GAG analysis which has been used is problematic since the values overlap with those in age-matched controls. Currently, urinary and blood KS and C6S, the enzyme activity of GALNS, and GALNS molecular analysis are used for diagnosis and prognosis of clinical phenotype in MPS IVA. MPS IVA can be diagnosed with unique characters although this disorder relates closely to other disorders in some characteristics. In this review article, we comprehensively describe clinical, radiographic, biochemical, and molecular diagnosis and clinical assessment tests for MPS IVA. We also compare MPS IVA to other closely related disorders to differentiate MPS IVA. Overall, imbalance of growth in MPS IVA patients underlies unique skeletal manifestations leading to a critical indicator for diagnosis.

Clinical presentation and diagnosis of mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are estimated to affect1 in 25,000 live births although specific rates vary between the ethnic origin and country. MPS are a group of lysosomal storage disorders, which cause the buildup of GAG(s) due to insufficient or absent GAG-degrading enzymes. With seven types of MPS disorders and eleven subtypes, the MPS family presents unique challenges for early clinical diagnosis due to the molecular and clinical heterogeneity between groups and patients. Novel methods of early identification, particularly newborn screening through mass spectrometry, can change the flow of diagnosis, allowing enzyme and GAG quantification before the presentation of clinical symptoms improving outcomes. Genetic testing of patients and their families can also be conducted preemptively. This testing enables families to make informed decisions about family planning, leading to prenatal diagnosis. In this review, we discuss the clinical symptoms of each MPS type as they initially appear in patients, biochemical and molecular diagnostic methods, and the future of newborn screening for this group of disorders.

Cardiac features and effects of enzyme replacement therapy in Taiwanese patients with Mucopolysaccharidosis IVA

BACKGROUND

Cardiac abnormalities have been observed in patients with mucopolysaccharidosis (MPS) of any type, with the most documented abnormalities being valvular heart disease and cardiac hypertrophy. However, few studies have focused on the cardiac features of MPS IVA.

METHODS

We reviewed the medical records, echocardiograms, and electrocardiograms of 32 Taiwanese patients with MPS IVA (16 males and 16 females; median age, 10.8 years; age range, 1.1 to 29.1 years) as well as the echocardiographic data of six patients who received enzyme replacement therapy (ERT) for 3-6 years.

RESULTS

Echocardiographic examinations (n = 32) revealed mean z scores of left ventricular mass index (LVMI), interventricular septum diameter in diastole (IVSd), left ventricular posterior wall diameter in diastole (LVPWd), and aortic diameter of 0.94, 2.70, 0.39, and 3.26, respectively. Z scores > 2 were identified in 25%, 50%, 29%, and 69% of the LVMI, IVSd, LVPWd, and aortic diameter values, respectively. Diastolic dysfunction [reversed ratio between early and late (atrial) ventricular filling velocity (E/A ratio < 1)] was identified in four patients (13%), however, the ejection fraction was normal (50-75%) in all of the patients. Sixteen patients (50%) had valvular heart disease and most were of mild degree. Fourteen (44%) had valvular stenosis, and 10 (31%) had regurgitation. The z scores of LVMI, IVSd, LVPWd, and aortic diameter, the severity scores of aortic stenosis and regurgitation, and the existence of a thickened interventricular septum were all positively correlated with increasing age (p < 0.05). For the 14 patients with valve thickening, the z scores of LVMI, IVSd and aortic diameter were all larger than those of the 18 patients without valve thickening (p < 0.05). For two patients who started ERT at a younger age (1.4 and 2.8 years, respectively), the z scores for LVMI, IVSd, and LVPWd all decreased after ERT.

CONCLUSIONS

A large proportion of the patients with MPS IVA had valvular heart disease and cardiac hypertrophy. Cardiac abnormalities worsened with increasing age in accordance with the progressive nature of this disease. ERT appeared to be effective in stabilizing or reducing cardiac hypertrophy, and better results may have been associated with starting ERT at a younger age.

Neurophysiology of hearing in patients with mucopolysaccharidosis type IV

BACKGROUND

Hearing impairment is a common problem in patients with mucopolysaccharidosis IV (MPS IV) throughout their life. Many of the adult patients with MPS IV exhibit permanent or severe hearing loss. However, there has been no systematic review of detailed audiological test results in MPS IV.

MATERIALS AND METHODS

Fourteen individuals with MPS IV (13 MPS IVA and 1 MPS IVB; aged between 12 and 38 years old) participated in the current study. We obtained auditory neurophysiological responses (auditory brainstem responses and otoacoustic emissions test) in addition to pure-tone audiometry and middle ear function tests (tympanometry and acoustic reflexes).

RESULTS

The results indicated various levels and types of hearing loss with abnormal neurophysiological responses even in those patients with MPS IVA with normal pure tone thresholds. We also found a strong relationship between height (short stature is an indicator of skeletal severity) and hearing sensitivity as well as a strong relationship between height and outer hair cell function in the inner ear (measured by otoacoustic emissions) among MPS IVA patients.

CONCLUSION

The strong correlation between reduced height and hearing loss indicates that patients with severe skeletal dysplasia may be at higher risk of developing more severe hearing loss. More importantly, the spectrum of hearing disorders indicates that MPS IV patients should have annual neurophysiological hearing tests in addition to audiometric testing from an early age regardless of their skeletal severity to more carefully monitor disease progression.