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

Health service utilization, economic burden and quality of life of patients with mucopolysaccharidosis in China

BACKGROUND

Patients with mucopolysaccharidosis (MPS) often face delayed diagnoses, limited treatment options and high healthcare costs, that may significantly affect patients' quality of life. The objective of this study was to understand medical service utilization related to diagnosis and treatment, economic burden during diagnosis period, and health-related quality of life among MPS patients in China.

METHODS

A series of patients diagnosed with MPS registered in the national patient organization were recruited for a cross-sectional survey from May to July 2019. Information were collected from patients or their parents via phone interview, including demographic data, utilization of services related to diagnosis and treatment, total cost during the period of MPS diagnosis and health-related quality of life (HRQoL). HRQoL was assessed by PedsQL 4.0 Generic Core Scale (PedsQL) and 36-item short-form health survey (SF-36) depending on the age of patients with MPS and compared with the general Chinese population.

RESULTS

A total of 180 MPS patients (50, 67, 15, 46, 1 and 1 for type I, II, III, IV, VI and VII), with a mean age of 9.54 years and 137 (76.11%) males, were included in analysis. The mean age at first visit to a medical doctor for MPS related symptoms was 3.65 ± 2.58 years old, while only 12 patients (6.67%) were diagnosed on their first visit. The mean diagnostic delay, which is defined as the time between the first visit to a medical doctor for MPS related symptoms and the final diagnosis, was 9.42 months, with no significant difference between types. The average number of misdiagnosis was 4.56. Before the confirmed diagnosis, the patients made an average of 6.31 visits and visited 4.3 hospitals. During diagnosis period, the mean of ¥81,086.72 direct medical costs accounted for 63.75% of the total cost. Only 32.78% of the patients had ever received specific treatments. The mean scores of PedsQL and SF-36 of patients were significantly lower than the Chinese norms. Household annual income per person, specific treatment use and MPS subtype were significantly associated HRQoL of patients.

CONCLUSION

The results highlight challenges faced by MPS patients in terms of diagnosis, access to specific treatments, economic burden and low HRQoL. There is an urgent need to improve early detection and diagnosis, create fair and consistent mechanisms to increase access to specialized treatment and reduce the economic burden of MPS patients in China.

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.

[Inborn error of metabolism and allogenic hematopoietic cell transplantation: Guidelines from the SFGM-TC]

Inherited Metabolic Diseases (IMD) are rare genetic diseases, including both lysosomal and peroxisomal diseases. Lysosomal diseases are related to the deficiency of one or more lysosomal enzymes or transporter. Lysosomal diseases are progressive and involve several tissues with most often neurological damage. Among peroxisomal diseases, X-linked adrenoleukodystrophy (ALD) is a neurodegenerative disease combining neurological and adrenal damage. For these diseases, enzyme replacement therapy (ERT), allogeneic hematopoietic cell transplantation (allo-HCT) and gene therapy represent various possible treatment options, used alone or in combination. The purpose of this workshop is to describe the indications, modalities, and follow-up of allo-HCT as well as the use of ERT peri-transplant. All indications for transplant in these rare diseases are associated with comorbidities and are subject to criteria that must be discussed in a dedicated national multidisciplinary consultation meeting. There are some consensual indications in type I-H mucopolysaccharidosis (MPS-IH) and in the cerebral form of ALD. For other IMDs, no clear benefit from the transplant has been demonstrated. The ideal donor is a non-heterozygous HLA-identical sibling. The recommended conditioning is myeloablative combining fludarabine and busulfan. In MPS-IH, ERT has to be started at diagnosis and continued until complete chimerism and normal enzyme assay are achieved. The pre-transplant assessment and post-transplant follow-up are made according to the published recommendations (PNDS). Standard follow-up is carried out jointly by the transplant and referral teams.

Understanding the challenges, unmet needs, and expectations of mucopolysaccharidoses I, II and VI patients and their caregivers in France: a survey study

BACKGROUND

Mucopolysaccharidoses (MPS) are a group of inherited lysosomal storage diseases caused by defective enzyme activity involved in the catalysis of glycosaminoglycans. Published data on adult patients with MPS remains scarce. Therefore, the present qualitative survey study was aimed at understanding knowledge of the disease, unmet needs, expectations, care, and overall medical management of adult/adolescent patients with MPS I, II and VI and their caregivers in France.

RESULTS

A total of 25 patients (MPS I, n_p = 11; MPS II, n_p = 9; MPS VI, n_p = 5) were included and about 36 in-depth interviews (caregivers alone, n_c = 8; patients-caregiver pair, n_c+p = 22; patients alone, n_p = 6) were conducted. Except one (aged 17 years), all patients were adults (median age: 29 years [17-50]) and diagnosed at median age of 4 years [0.4-30], with mainly mothers as caregivers (n_c = 16/19). Patients were classified into three groups: Group A, Patients not able to answer the survey question because of a severe cognitive impairment (n_p = 8); Group B, Patients able to answer the survey question with low or no cognitive impairment and high motor disability (n_p = 10); and Group C, Patients able to answer the survey question with low or no cognitive impairment and low motor disability (n_p = 7). All groups were assessed for impact of disease on their daily lives based on a scale of 0-10. Caregivers in Group A were found to be most negatively affected by the disease, except for professional activity, which was most significantly impacted in Group B (4.7 vs. 5.4). The use of orthopaedic/medical equipments, was more prevalent in Groups A and B, versus Group C. Pain management was one of the global unmet need expressed by all groups. Group A caregivers expected better support from childcare facilities, disability clinics, and smooth transition from paediatric care to adult medicine. Similarly, Group B caregivers expected better specialised schools, whereas Group C caregivers expected better psychological support and greater flexibility in weekly infusion schedules for their patients.

CONCLUSIONS

The survey concluded that more attention must be paid to the psychosocial status of patients and caregivers. The preference for reference centre for follow-up and treatment, hospitalizations and surgeries were evident. The most significant needs expressed by the patients and caregivers include better understanding of the disease, pain management, monitoring of complications, flexibility in enzyme replacement therapy, home infusions especially for attenuated patients, and improved transitional support from paediatric to adult medicine.

A novel splicing variant in GALNS in mucopolysaccharidosis IVA and the necessity of re-evaluating primer sequences

Mucopolysaccharidosis type IVA (MPS IVA; Morquio syndrome type A) is an autosomal recessive disorder caused by defects in the lysosomal hydrolase N-acetylgalactosamine-6-sulfatase (GALNS) gene, leading to progressive systemic skeletal dysplasia. Early diagnosis and early intervention with enzyme replacement therapy are crucial for improving outcomes in these patients. However, a relatively high number of patients are genetically undiagnosed due to high allelic heterogeneity and the absence of robust functional evidence for most variants of the GALNS gene. Herein, we report a novel intronic variant identified with RNA analysis and an allele dropout (ADO) event caused by a common benign variant in the primer-binding site in a Korean boy with MPS IVA. A 28-month-old boy presented with pectus carinatum, kyphoscoliosis, and joint hypermobility with multiple skeletal dysplasia involving the vertebrae and hip joint. Total urinary glycosaminoglycans were elevated with a predominant keratan sulfate fraction, and GALNS (EC 3.1.6.4) activity was significantly decreased in leukocytes. Sanger sequencing was performed; however, only one heterozygous intronic variant with uncertain clinical significance, c.566+3A > T (p.(?)), was identified. As the patient exhibited clinical and biochemical features of MPS IVA, we conducted whole genome sequencing (WGS) of the patient and his family to clarify the molecular diagnosis. WGS revealed a compound heterozygous genotype, c.1019G > A (p.(Gly340Asp)) and c.566+3A > T (p.(?)), in the GALNS gene. On mRNA sequencing, c.566+3A > T, was confirmed to cause exon 5 skipping and a premature stop codon. With subsequent investigation, we discovered that the variant, c.1019G > A, was undetected on initial sequencing because of ADO due to a common benign variant (rs3859024:G > C) at the primer annealing location. We present a novel intronic variant with a splicing defect in the GALNS gene and suggest that clinicians review primer sequences in cases not diagnosed on Sanger sequencing before progressing to diagnostic steps such as WGS.

Liver-Directed Adeno-Associated Virus-Mediated Gene Therapy for Mucopolysaccharidosis Type VI

BACKGROUND: Mucopolysaccharidosis type VI (MPS VI) is an inherited multisystem lysosomal disorder due to arylsulfatase B (ARSB) deficiency that leads to widespread accumulation of glycosaminoglycans (GAG), which are excreted in increased amounts in urine. MPS VI is characterized by progressive dysostosis multiplex, connective tissue and cardiac involvement, and hepatosplenomegaly. Enzyme replacement therapy (ERT) is available but requires life-long and costly intravenous infusions; moreover, it has limited efficacy on diseased skeleton and cardiac valves, compromised pulmonary function, and corneal opacities. METHODS: We enrolled nine patients with MPS VI 4 years of age or older in a phase 1/2 open-label gene therapy study. After ERT was interrupted, patients each received a single intravenous infusion of an adeno-associated viral vector serotype 8 expressing ARSB. Participants were sequentially enrolled in one of three dose cohorts: low (three patients), intermediate (two patients), or high (four patients). The primary outcome was safety; biochemical and clinical end points were secondary outcomes. RESULTS: The infusions occurred without severe adverse events attributable to the vector, meeting the prespecified end point. Participants in the low and intermediate dose cohorts displayed stable serum ARSB of approximately 20% of the mean healthy value but returned to ERT by 14 months after gene therapy because of increased urinary GAG. Participants in the high-dose cohort had sustained serum ARSB of 30% to 100% of the mean healthy value and a modest urinary GAG increase that did not reach a concentration at which ERT reintroduction was needed. In the high-dose group, there was no clinical deterioration for up to 2 years after gene therapy. CONCLUSIONS: Liver-directed gene therapy for participants with MPS VI did not have a dose-limiting side-effect and adverse event profile; high-dose treatment resulted in ARSB expression over at least 24 months with preliminary evidence of disease stabilization. (Funded by the Telethon Foundation ETS, the European Commission Seventh Framework Programme, and the Isaac Foundation; ClinicalTrials.gov number, NCT03173521; EudraCT number, 2016-002328-10.)

Misdiagnosis in mucopolysaccharidoses

Mucopolysaccharidosis (MPS) is a group of 13 hereditary metabolic diseases identified in humans (or 14 diseases if considering one MPS type described to date only in mice) in which an enzymatic defect results in the accumulation of glycosaminoglycans (GAG) in the lysosomes of cells. First of all, as a result of GAG storage, the proper functioning of the lysosome is disturbed; then, the cells, and finally, tissue, organs, and the whole organism malfunctions are observed. Due to the rarity, heterogeneity, and multi-systemic and progressive nature of MPS, they present a major diagnostic challenge. Due to the wide variation in symptoms and their similarity to other diseases, MPS is often misdiagnosed, usually as neurological diseases (like autism spectrum disorders, psychomotor hyperactivity, and intellectual disability) or rheumatology and orthopedic disorders (like juvenile idiopathic arthritis, Perthes disease, rickets, and muscular dystrophy). In this review article, we present the problems associated with the possibility of misdiagnosing MPS, discuss what diseases they can be confused with, and suggest ways to reduce these problems in the future.

Addressing the need for patient-friendly medical communications: adaptation of the 2019 recommendations for the management of MPS VI and MPS IVA

BACKGROUND

Patients are the most important stakeholders in the care of any disease and have an educational need to learn about their condition and the treatment they should receive. Considering this need for patient-focused materials, we present a directed approach for mucopolysaccharidosis (MPS) VI and MPS IVA, a pair of rare, inherited diseases that affects multiple organs and parts of the body. Independent guidelines on the treatment of these diseases were recently published, providing evidence- and expertise-driven recommendations to optimize patient management. However, while healthcare providers may have the training and knowledge to understand these guidelines, patients and their caregivers can find the technical content challenging. Hence, we aimed to develop plain language summaries (PLS) of the MPS VI and MPS IVA guidelines with patients as the primary audience.

RESULTS

A review of the guidelines by an expert team identified six domains of information relevant to patients: The multidisciplinary team, regular tests and check-ups, disease-modifying and supportive treatments, general anesthetics, ear-nose-throat/respiratory care, and surgeries. This information was adapted into a series of infographics specific to either MPS VI or MPS IVA, designed to appeal to patients and clearly present information in a concise manner.

CONCLUSIONS

The use of patient-friendly materials, like the infographics we have developed, has the potential to better inform patients and engage them in their care. We issue a "call to arms" to the medical community for the development of similar PLS materials in rare diseases intended to inform and empower 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.

Recommended respiratory tests are not routinely performed for mucopolysaccharidosis patients

Mucopolysaccharidoses (MPS) are a group of rare genetic lysosomal storage disorders. The seven types of MPS exhibit a wide spectrum of clinical severity, including cognitive impairment, skeletal and joint abnormalities, short stature, coarsened facial features, vision loss, and cardiovascular and respiratory impairment, which are the leading causes of morbidity and mortality among MPS patients [1–3]. Ear, nose and throat (ENT) and upper airway manifestations are initially more pronounced, and may lead to the initial diagnosis. Lower airway disease becomes more frequent with increasing age. Symptoms can be tracheomalacia, stenosis and bronchomalacia. Bronchitis and pneumonia can appear, and are due to increased secretions and poor airway clearance. Restrictive lung disease predominates among patients with significant skeletal involvement, namely MPS-IV and MPS-VI. Sleep disturbances and obstructive sleep apnoea secondary to airway obstruction are common [4]. Specific therapy, such as enzyme replacement therapy (ERT), is available for most types of MPS.

Recommended respiratory tests used as major outcomes in clinical trials for MPS treatment cannot be routinely performed in everyday practice because neurocognitive impairment and motor skill difficulties affect compliance for most MPS patientshttps://bit.ly/3G4qp8U

The Outcome of Allogeneic Hematopoietic Stem Cell Transplantation From Different Donors in Recipients With Mucopolysaccharidosis

There is limited information regarding hematopoietic stem cell transplantation (HSCT) for mucopolysaccharidosis (MPS) IV and VI. This study examined the full donor chimerism, specific lysosomal enzyme levels, and the survival of different MPS children after HSCT from various donor sources and compared the prognosis. A total of 42 children with MPS underwent HSCT, 9 cases were type I, 14 were type II, 15 were type IV, and 4 were type VI. A total of 24 patients received peripheral blood stem cells (PBSC) and 18 patients received umbilical cord blood (UCB). Patients who received PBSC were conditioned with intravenous (IV) busulfan every 6 h for a total of 16 doses, IV cyclophosphamide (CY, 200 mg/kg), and antihuman thymocyte globulin (ATG, 10 mg/kg). While conditioning regimen of patients who received UCB was adjusted to ATG (preposed, pre-) + busulfan + fludarabine + Cy, which includes IV ATG (pre-, 6 mg/kg), IV busulfan every 6 h for a total of 16 doses, IV fludarabine (200 mg/m²) and CY (200 mg/kg). Also, 95.2% (40 of 42) of patients achieved full donor chimerism, and all patients' specific lysosomal enzyme levels reached normal. The estimated overall survival (OS) at 1 year was 92.9%. There was no significant difference in 1-year OS between patients who received PBSC transplantation and those who received UCB grafts (87.5% vs. 100%, p = 0.0247). The incidence of acute and chronic GVHD did not differ between them. The incidences of pneumonia in PBSC recipients and UCB recipients were 45.8 and 33.3%, respectively, but there few patients suffering from respiratory failure (4.2 and 5.6%, respectively) due to pneumonia. The incidence of cytomegaloviremia was also high in both groups, 58.3 and 44.4% respectively, However, no patient developed CMV disease. All deaths (3 of 42) occurred in patients receiving PBSC grafts, and there was no death in patients receiving UCB grafts. There was no death after transplantation in patients with MPS IV and VI. In addition, respiratory and nervous system functions were improved, whereas valvular heart disease was improved in some patients but progressed in more patients after transplantation. In summary, HSCT is a good therapeutic option for MPS, not only for patients with MPS I or II but also for those with MPS IV or VI. The specific lysosomal enzyme levels can be completely restored to normal, which is the basis for patients to resolve a broad range of clinical outcomes. Moreover, UCB with suitable HLA (HLA-match above 7/10 and 4/6) is a suitable donor source for MPS. Patients who underwent UCB transplantation using the conditioning regimen ATG (pre-) + busulfan + fludarabine + Cy can achieve a higher proportion of full donor chimerism and survival with less severe complications. HSCT can improve organs function in patients with MPS, but it is still worth exploring.

Mucopolysaccharidosis Type VI, an Updated Overview of the Disease

Mucopolysaccharidosis type VI, or Maroteaux-Lamy syndrome, is a rare, autosomal recessive genetic disease, mainly affecting the pediatric age group. The disease is due to pathogenic variants of the ARSB gene, coding for the lysosomal hydrolase N-acetylgalactosamine 4-sulfatase (arylsulfatase B, ASB). The enzyme deficit causes a pathological accumulation of the undegraded glycosaminoglycans dermatan-sulphate and chondroitin-sulphate, natural substrates of ASB activity. Intracellular and extracellular deposits progressively take to a pathological scenario, often severe, involving most organ-systems and generally starting from the osteoarticular apparatus. Neurocognitive and behavioral abilities, commonly described as maintained, have been actually investigated by few studies. The disease, first described in 1963, has a reported prevalence between 0.36 and 1.3 per 100,000 live births across the continents. With this paper, we wish to contribute an updated overview of the disease from the clinical, diagnostic, and therapeutic sides. The numerous in vitro and in vivo preclinical studies conducted in the last 10-15 years to dissect the disease pathogenesis, the efficacy of the available therapeutic treatment (enzyme replacement therapy), as well as new therapies under study are here described. This review also highlights the need to identify new disease biomarkers, potentially speeding up the diagnostic process and the monitoring of therapeutic efficacy.

Mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome): defining and measuring functional impacts in pediatric patients

BACKGROUND

Research about pediatric patients' perspective on mucopolysaccharidosis type VI (MPS VI) and its impact on daily life is limited. We aimed to identify the disease concepts of interest that most impact function and day-to-day life of pediatric patients with MPS VI, and to consider clinical outcome assessments (COAs) that may potentially measure meaningful improvements in these concepts.

METHODS

Potential focus group participants were identified by the National MPS Society (USA) and invited to participate if they self-reported a clinician-provided diagnosis of MPS VI and were 4 to 18 years, receiving enzyme replacement therapy (ERT), and available to attend a 1-day focus group with their caregiver in Dallas, TX, USA. The focus group consisted of a series of polling and open-ended concept elicitation questions and a cognitive debriefing session. The discussion was audio recorded, transcribed verbatim, and analyzed to identify disease concepts of interest and functional impacts most relevant to participants.

RESULTS

Overall, caregivers (n = 9) and patients with MPS VI (n = 9) endorsed that although their children/they receive ERT, residual symptoms exist and impact health-related quality of life. The key disease concepts of interest identified were impaired mobility, upper extremity and fine motor deficits, pain, and fatigue. Pain was unanimously reported by all patients across many areas of the body and impacted daily activity. Key disease concepts were mapped to a selection of pediatric COAs including generic measures such as PROMIS®, PODCI, CHAQ, and PedsQL™. Caregivers endorsed the relevance of PODCI and PROMIS Upper Extremity, Mobility, and Pain items and all patients completed the NIH Toolbox Pegboard Dexterity Test. Additional COAs that aligned with the disease concepts included range of motion, the 2- and 6-min walk tests, timed stair climbs, Bruininks-Oseretsky Test of Motor Proficiency, 2nd edition, grip strength, pain visual analog scale, and the Faces Pain Scale-Revised.

CONCLUSION

An MPS VI focus group of pediatric patients and their caregivers identified impaired mobility, upper extremity and fine motor deficits, pain, and fatigue as key disease concepts of interest. These disease concepts were mapped to existing pediatric COAs, which were provided to the group for endorsement of their relevance.

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.

Clinical outcomes of laminoplasty for patients with lysosomal storage disease including mucopolysaccharidosis and mucolipidoses: a retrospective cohort study

Background

Although the clinical efficacy of laminoplasty in adult cervical spondylotic myelopathy or ossification of posterior longitudinal ligament has been frequently reported, there are only few reports of laminoplasty for patients with lysosome storage diseases (LSDs). Therefore, this study aimed to report the midterm clinical and radiological outcomes of patients with LSDs after cervical laminoplasty.

Methods

Six patients with LSD who underwent laminoplasty with/without C1 laminectomy for cervical myelopathy were enrolled. Clinical evaluations, including the cervical Japanese Orthopedic Association (cJOA) score and visual analog scale (VAS) scores for upper extremity numbness, and radiographic parameters, including C2–C7 lordotic angle, atlanto-dens interval (ADI), and ⊿ADI, were evaluated preoperatively, at 2 years postoperatively, and at the final follow-up.

Results

Five patients had mucopolysaccharidoses (type I: n = 1, II: n = 3, VII: n = 1) and one patient had mucolipidoses type III. The mean age of patients at surgery was 27.5 years, and the mean postoperative follow-up period was 61 months. All mucopolysaccharidoses cases required C1 posterior arch resection with C2–C7 laminoplasty. No critical complications were observed postoperatively. There were no significant differences in C2–C7 angle (p = 0.724) and ⊿ADI (p = 0.592) between the preoperative and final follow-ups. The cJOA score and VAS for numbness significantly improved at the final follow-up (p = 0.004 and p = 0.007, respectively).

Conclusions

The cervical myelopathy in patients with LSD could be safely and effectively treated with laminoplasty with/without C1 posterior arch resection after excluding patients with atlantoaxial instability. Atlantoaxial stability and symptom improvement could be maintained at an average of 5 years postoperatively.

Disease burden, management patterns and multidisciplinary clinical approaches for patients with MPS IVA and VI in selected Latin American Countries

Background

There is a paucity of real-world epidemiological data on patients with mucopolysaccharidoses (MPS) in Latin America. This real-world study assessed the disease burden, management patterns and multidisciplinary clinical approaches for MPS-IVA and MPS-VI patients in Latin America (Colombia, Ecuador, Mexico, Peru).

Methods

Data were collected from physicians/specialists experienced in treating MPS patients between April–June 2020, via an online patient-diary survey.

Results

Overall, 29 physicians/specialists participated in this study. Data from 98 patients were analyzed (MPS-IVA, 71 patients and MPS-VI, 27 patients). Mean age for MPS-IVA patients was 17.5 years and for MPS-VI patients was 11.6 years, and the majority were females (52% and 78%, respectively). MPS-IVA and VI patients presented a high absenteeism from school (55% and 37%, respectively; <18 years age) and workplace (78% and 100%, respectively; >18 years age), indicating an impact of the disease on some aspects of the patients' quality of life. The onset of the first symptom occurred at the age of 3.1 years for MPS-IVA patients and at 1 year for MPS-VI, with delay in diagnosis (3.5–3.9 years from symptom onset) and enzyme replacement therapy (ERT) initiation (1.1–3.6 years from diagnosis). ERT interruptions were observed for MPS-IVA (48%) and MPS-VI patients (44%), with non-availability of medication recorded as the main reason for non-adherence (46% and 60% patients, respectively). ERT showed noticeable treatment benefits in MPS-IVA/VI patients, with stabilization/reduction in complications or the number of surgeries. A multidisciplinary clinical team approach was used for patient management.

Conclusion

The disease burden for MPS-IVA/VI was high in Latin America, with consistent management, treatment and socio-demographic trends throughout the region.

Long-term outcomes of patients with mucopolysaccharidosis VI treated with galsulfase enzyme replacement therapy since infancy

OBJECTIVE

Long-term outcomes of patients with mucopolysaccharidosis (MPS) VI treated with galsulfase enzyme replacement therapy (ERT) since infancy were evaluated.

METHODS

The study was a multicenter, prospective evaluation using data from infants with MPS VI generated during a phase 4 study (ASB-008; Clinicaltrials.govNCT00299000) and clinical data collected ≥5 years after completion of the study.

RESULTS

Parents of three subjects from ASB-008 (subjects 1, 2, and 4) provided written informed consent to participate in the follow-up study. One subject was excluded as consent was not provided. Subjects 1, 2, and 4 were aged 0.7, 0.3, and 1.1 years, respectively, at initiation of galsulfase and 10.5, 7.9, and 10.5 years, respectively, at follow-up. All subjects had classical MPS VI based on pre-treatment urinary glycosaminoglycans and the early onset of clinical manifestations. At follow-up, subject 4 had normal stature for age; subjects 1 and 2 had short stature, but height remained around the 90th percentile of growth curves for untreated classical MPS VI. Six-minute walk distance was normal for age/height in subjects 1 (550 m) and 4 (506 m), and reduced for subject 2 (340 m). Subject 2 preserved normal respiratory function, while percent predicted forced vital capacity and forced expiratory volume in 1 s decreased over time in the other subjects. Skeletal dysplasia was already apparent in all subjects at baseline and continued to progress. Cardiac valve disease showed mild progression in subject 1, mild improvement in subject 4, and remained trivial in subject 2. All subjects had considerably reduced pinch and grip strength at follow-up, but functional dexterity was relatively normal for age and there was limited impact on activities of daily living. Bruininks-Oseretsky Test of Motor Proficiency (BOT-2) results showed that subjects 2 and 4 had numerous fine and gross motor competencies. Corneal clouding progressed in all subjects, while progression of hearing impairment was variable. Liver size normalized from baseline in subjects 1 and 4, and remained normal in subject 2.

CONCLUSION

Very early and continuous ERT appears to slow down the clinical course of MPS VI, as shown by preservation of endurance, functional dexterity, and several fine and gross motor competencies after 7.7-9.8 years of treatment, and less growth impairment or progression of cardiac disease than could be expected based on the patients' classical phenotype. ERT does not seem to prevent progression of skeletal or eye disease in the long term.

Knee and ankle disorders during functional gait in mucopolysaccharidosis type VI

ABSTRACT To evaluate knee and ankle disorders during functional gait assessment in individuals with Mucopolysaccharidosis type VI (MPS VI). 19 subjects were included in this cross-sectional study and allocated in three groups according to age: Children Group (n=11); Adolescent Group (n=4); and Adult Group (n=4). Subphases of one gait cycle were analyzed: Initial contact; Medium support, and Pre-Balance. All volunteers with MPS VI presented greater knee and ankle flexion angles, in all gait subphases, when compared to the normal values defined by literature (p<0.05). Initial contact subphase: knee flexion angle ranging from 8.5º to 15º; Ankle = Child Group −23.73º ± 8.53º; Adolescent Group = −25º ± 11.22º; Adult Group = −27.75º ± 3.3º. Medium support subphase: Knee = Child Group 19.64º ± 10.47º; Adolescent Group 16.75º ± 10.34º; Adult Group = 21.25º ± 12.84º. Ankle = Child Group −18.82º ± 8.91º ± 8.53º; Adolescent Group = −16.5º ± 9.33º; Adult Group = −22.25º ± 4.19º. Pre-Balance subphase: Knee = Child Group 22.72º ± 13.49º; Adolescent Group 21.25º ± 7.97º; Adult Group = 27º ± 16.27º. Ankle = Child Group -15º ± 9.76º; Adolescent Group = −15.75º ± 5.31º; Adult Group = −14.75º ± 3.86º. In this study, MPS VI individuals presented hyperflexion of knee and ankle as the main joint disorders during functional gait, regardless of age.

Hearing Loss in Mucopolysaccharidoses: Current Knowledge and Future Directions

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by a deficiency of one of the enzymes involved in the degradation of glycosaminoglycans. Hearing loss is a common clinical presentation in MPS. This paper reviews the literature on hearing loss for each of the seven recognized subtypes of MPS. Hearing loss was found to be common in MPS I, II, III, IVA, VI, and VII, and absent from MPS IVB and MPS IX. MPS VI presents primarily with conductive hearing loss, while the other subtypes (MPS I, MPS II, MPS III, MPS IVA, and MPS VII) can present with any type of hearing loss (conductive, sensorineural, or mixed hearing loss). The sensorineural component develops as the disease progresses, but there is no consensus on the etiology of the sensorineural component. Enzyme replacement therapy (ERT) is the most common therapy utilized for MPS, but the effects of ERT on hearing function have been inconclusive. This review highlights a need for more comprehensive and multidisciplinary research on hearing function that includes behavioral testing, objective testing, and temporal bone imaging. This information would allow for better understanding of the progression and etiology of hearing loss. Owing to the prevalence of hearing loss in MPS, early diagnosis of hearing loss and annual comprehensive audiological evaluations are recommended.

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.

Enzyme replacement therapy interruption in patients with Mucopolysaccharidoses: Recommendations for distinct scenarios in Latin America

Background

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders, leading to the progressive accumulation of glycosaminoglycans (GAGs) and the subsequent compromising of tissues and organ malfunction. Although incurable, most types of MPS can be treated with enzyme replacement therapy (ERT), an approach that has had positive effects on the natural clinical evolution and which impact has been extensively investigated. Unfortunately, to date, there is relatively little data regarding the effects of ERT interruption, especially in Latin America, where such interruption may be frequent due to a variety of issues (for instance, difficulties involving logistics, reimbursement and/or payment withdrawal).

Method

A group of medical professionals from Latin America with experience in Genetics, Pediatrics and Neurology held an Advisory Board Meeting in the city of São Paulo, in October 2018, to discuss the issue of ERT interruptions in the region and recommendations health care professionals on how to deal with these interruptions and better assess the therapeutic effects of ERT.

Conclusion

Recommendations provided by the experts may support physicians in dealing with the most common reasons for ERT interruptions in Latin America. Most importantly, recommendations for data collection at specific timepoints (at baseline, throughout the treatment and during the interruption period of ERT and after its resumption) can significantly improve the collection of real world evidence on the effects of ERT and its interruptions, supporting health care professionals and policy makers in the decision making regarding the provision of these therapies for MPS patients.

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Positive impact of ERT is reported in MPS patients, but the effects of its interruption is overlooked.

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In Latin America, ERT interruption is not infrequent. A systematic evaluation the worsening of MPS progression is vital.

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The proposed structured data collection would help to evaluate patients and generate real word data.

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We encourage studies and experts discussions for a better understand the value of ERT for MPS patients in Latin America.

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.

Surgical Management of Spinal Disorders in People with Mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are a group of inherited, multisystem, lysosomal storage disorders involving specific lysosomal enzyme deficiencies that result in the accumulation of glycosaminoglycans (GAG) secondary to insufficient degradation within cell lysosomes. GAG accumulation affects both primary bone formation and secondary bone growth, resulting in growth impairment. Typical spinal manifestations in MPS are atlantoaxial instability, thoracolumbar kyphosis/scoliosis, and cervical/lumbar spinal canal stenosis. Spinal disorders and their severity depend on the MPS type and may be related to disease activity. Enzyme replacement therapy or hematopoietic stem cell transplantation has advantages regarding soft tissues; however, these therapeutic modalities are not effective for bone or cartilage and MPS-related bone deformity including the spine. Because spinal disorders show the most serious deterioration among patients with MPS, spinal surgeries are required although they are challenging and associated with high anesthesia-related risks. The aim of this review article is to provide the current comprehensive knowledge of representative spinal disease in MPS and its surgical management, including the related pathology, symptoms, and examinations.