Unique medical issues in adult patients with mucopolysaccharidoses

Cardiac Manifestations in Inherited Metabolic Diseases

Inherited metabolic diseases (IMDs) stem from genetic defects affecting enzyme function within specific metabolic pathways, collectively constituting rare conditions with an incidence of less than 1/100,000 births. While IMDs typically manifest with multisystemic symptoms, cardiac manifestations are common, notably hypertrophic cardiomyopathy. Additionally, they can lead to dilated or restrictive cardiomyopathy, as well as noncompacted left ventricular cardiomyopathy. Rhythm disturbances such as atrioventricular conduction abnormalities, Wolff-Parkinson-White syndrome, and ventricular arrhythmias, along with valvular pathologies and ischemic coronary issues, are also prevalent. This study aims to provide a narrative review of IMDs associated with cardiac involvement, delineating the specific cardiac manifestations of each disorder alongside systemic symptoms pivotal for diagnosis.

Cardiac manifestations in inherited metabolic diseases

Inherited metabolic diseases (IMD) are caused by the functional defect of an enzyme, of genetic origin, that provokes a blockage in a specific metabolic pathway. Individually, IMD are considered rare diseases, with an incidence of less than 1/100,000 births. The symptoms are usually multisystemic, but frequently include cardiac manifestations. Of these, the most common are cardiomyopathies, especially hypertrophic cardiomyopathy. In addition, they can cause dilated or restrictive cardiomyopathy and non-compacted cardiomyopathy of the left ventricle. Characteristic signs also include rhythm alterations (atrio-ventricular conduction disturbances, Wolff-Parkinson-White syndrome or ventricular arrhythmias), valvular pathology and ischaemic coronary pathologies. The aim of this study is to present a narrative review of the IMD that may produce cardiac involvement. We describe both the specific cardiac manifestations of each disease and the systemic symptoms that guide diagnosis.

Clinical, biochemical, and molecular characterization of mucopolysaccharidosis type III in 34 Egyptian patients

Mucopolysaccharidosis type III (MPS III) is a rare autosomal recessive lysosomal storage disorder characterized by progressive neurocognitive deterioration. There are four MPS III subtypes (A, B, C, and D) that are clinically indistinguishable with variable rates of progression. A retrospective analysis was carried out on 34 patients with MPS III types at Cairo University Children's Hospital. We described the clinical, biochemical, and molecular spectrum of MPS III patients. Of 34 patients, 22 patients had MPS IIIB, 7/34 had MPS IIIC, 4/34 had MPS IIIA, and only 1 had MPS IIID. All patients presented with developmental delay/intellectual disability, and speech delay. Ataxia was reported in a patient with MPS IIIC, and cerebellar atrophy in a patient with MPS IIIA. We reported 25 variants in the 4 MPS III genes, 11 of which were not previously reported. This is the first study to analyze the clinical and genetic spectrum of MPS III patients in Egypt. This study explores the genetic map of MPS III in the Egyptian population. It will pave the way for a national registry for rare diseases in Egypt, a country with a high rate of consanguineous marriage and consequently a high rate of autosomal recessive disorders.

The gene therapy for corneal pathology with novel nonsense cystinosis mouse lines created by CRISPR Gene Editing

PURPOSE

Cystinosis is an autosomal recessive lysosomal storage disease (LSDs) caused by mutations in the gene encoding cystinosin (CTNS) that leads to cystine crystal accumulation in the lysosome that compromises cellular functions resulting in tissue damage and organ failure, especially in kidneys and eyes. However, the underlying molecular mechanism of its pathogenesis remains elusive. Two novel mice lines created via CRISPR are used to examine the pathogenesis of cystinosis in the kidney and cornea and the treatment efficacy of corneal pathology using self-complimentary Adeno-associated viral (scAAV-CTNS) vector.

METHODS

The CRISPR technique generated two novel cystinotic mouse lines, Ctnsis1 (an insertional mutation) and Ctnsis2 (a nonsense mutation). Immune histochemistry, renal functions test and HRT2 in vivo confocal microscopy were used to evaluate the age-related renal pathogenesis and treatment efficacy of the scAAV-CTNS virus in corneal pathology.

RESULTS

Both mutations lead to the production of truncated Ctns proteins. Ctnsis1 and Ctnsis 2 mice exhibit the characteristic of cystinotic corneal crystal phenotype at four-week-old. Treatment with the scAAV-CTNS viral vector decreased the corneal crystals in the treated mice cornea. Ctnsis 1 show renal abnormalities manifested by increased urine volume, reduced urine osmolality, and the loss of response to Desmopressin (dDAVP) at 22-month-old but Ctnsis2 don't manifest renal pathology up to 2 years of age.

CONCLUSIONS

Both Ctnsis1 and Ctnsis2 mice exhibit phenotypes resembling human intermediate nephropathic and ocular cystinosis, respectively. scAAV-CTNS viral vectors reduce the corneal cystine crystals and have a great potential as a therapeutic strategy for treating patients suffering from cystinosis.

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.

Natural History and Molecular Characteristics of Korean Patients with Mucopolysaccharidosis Type III

Background: Mucopolysaccharidosis type III (MPS III) is an autosomal recessive lysosomal storage disorder characterised by progressive neurocognitive deterioration. MPS III subtypes are clinically indistinguishable, with a wide range of symptoms and variable severity. The natural history of this disorder within an Asian population has not yet been extensively studied. This study investigated the natural history of Korean patients with MPS III. Methods: Thirty-four patients from 31 families diagnosed with MPS III from January 1997 to May 2020 in Samsung Medical Centre were enrolled. Clinical, molecular, and biochemical characteristics were retrospectively collected from the patients’ medical records and via interviews. Results: 18 patients had MPS IIIA, 14 had IIIB, and two had IIIC. Twenty (58.9%) patients were male. Mean age at symptom onset was 2.8 ± 0.8 years and at diagnosis was 6.3 ± 2.2 years. All patients with MPS IIIA and IIIB were classified into the rapidly progressing (RP) phenotype. The most common symptom at diagnosis was language retardation (88.2%), followed by motor retardation (76.5%), general retardation (64.7%), and hyperactivity (41.2%). Language retardation was more predominant in IIIA, and motor retardation was more predominant in IIIB. The mean age of the 13 deceased patients at the time of the study was 14.4 ± 4.1 years. The age at diagnosis and lag time were significantly older and longer in the non-survivor group compared with the survivor group (p = 0.029 and 0.045, respectively). Genetic analysis was performed in 24 patients with MPS III and identified seven novel variants and three hot spots. Conclusion: This study is the first to analyse the genetic and clinical characteristics of MPS III patients in Korea. Better understanding of the natural history of MPS III might allow early diagnosis and timely management of the disease and evaluation of treatment outcomes in future clinical trials for MPS III.

The landscape of Mucopolysaccharidosis in Southern and Eastern European countries: a survey from 19 specialistic centers

Background

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by defects in genes coding for different lysosomal enzymes which degrade glycosaminoglycans. Impaired lysosomal degradation causes cell dysfunction leading to progressive multiorgan involvement, disabling consequences and poor life expectancy. Enzyme replacement therapy (ERT) is now available for most MPS types, offering beneficial effects on disease progression and improving quality of life of patients. The landscape of MPS in Europe is not completely described and studies on availability of treatment show that ERT is not adequately implemented, particularly in Southern and Eastern Europe. In this study we performed a survey analysis in main specialist centers in Southern and Eastern European countries, to outline the picture of disease management in the region and understand ERT implementation. Since the considerable number of MPS IVA patients in the region, particularly adults, the study mainly focused on MPS IVA management and treatment.

Results

19 experts from 14 Southern and Eastern European countries in total responded to the survey. Results outlined a picture of MPS management in the region, with a high number of MPS patients managed in the centers and a high level of care. MPS II was the most prevalent followed by MPS IVA, with a particular high number of adult patients. The study particularly focused on management and treatment of MPS IVA patients. Adherence to current European Guidelines for follow-up of MPS IVA patients is generally adequate, although some important assessments are reported as difficult due to the lack of MPS skilled specialists. Availability of ERT in Southern and Eastern European countries is generally in line with other European regions, even though regulatory, organizational and reimbursement constrains are demanding.

Conclusions

The landscape of MPS in Southern and Eastern European countries is generally comparable to that of other European regions, regarding epidemiology, treatment accessibility and follow up difficulties. However, issues limiting ERT availability and reimbursement should be simplified, to start treatment as early as possible and make it available for more patients. Besides, educational programs dedicated to specialists should be implemented, particularly for pediatricians, clinical geneticists, surgeons, anesthesiologists and neurologists.

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.

Hunter Syndrome: The Phenotype of a Rare Storage Disease

Hunter syndrome is a rare lysosomal storage disorder with systemic involvement that occurs over time. Affected patients have coarse facial features, growth retardation with short stature, and skeletal deformities called dysostosis multiplex; joint stiffness, progressive mental retardation, and organomegaly are some of the clinical signs. It ranges from mild to severe manifestations and the distinction between them is related to neurological involvement. Cardiac and respiratory failure is commonly the cause of early death (before adulthood) for severe forms, but those with attenuated forms who have normal cognitive development can survive until late adulthood. Treatment with enzyme replacement therapy is available and can improve the prognosis of this disease. The authors present a case of a 36-year-old male with Hunter syndrome to show not only the clinical features typical of this multisystemic disease that should alert to a prompt investigation but also to remind that treatment must start as early as possible to reach the best outcome. Management of this disease is typically challenging and requires a multidisciplinary approach.

Surgical Management of Valvular Heart Disease in Mucopolysaccharidoses: A Review of Literature

Mucopolysaccharidoses are extremely rare diseases that are frequently presenting with structural heart problems of the aortic and mitral valve in combination with myocardial dysfunction. In a substantial proportion, this leads to heart failure and is a leading cause of death in these patients. As this glycosaminoglycan degradation defect is associated with other conditions strongly influencing the perioperative risk and choice of surgical technique, multidisciplinary planning is crucial to improve short- and long-term outcomes. The extensive variance in clinical presentation between different impaired enzymes, and further within subgroups, calls for personalised treatment plans. Enzyme replacement therapies and bone marrow transplantation carry great potential as they may significantly abrogate the progress of the disease and as such reduce the clinical burden and improve life expectancy. Nevertheless, structural heart interventions may be required. We reviewed the existing literature of the less than 50 published cases regarding surgical management, technique, and choice of prostheses. Although improvement in therapy has shown promising results in protecting valvar tissue when initiated in infancy, concerns regarding stability of this effect and durability of biological prostheses remain.

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.

Hyo-Mental Angle and Distance: An Important Adjunct in Airway Assessment of Adult Mucopolysaccharidosis

Background: Mucopolysaccharidosis (MPS) is a rare congenital lysosomal storage disorder with complex airways. High anterior larynx is assessed by thyromental distance (TMD) nasendoscopy. A simpler method to assess this hyoid bone is described. The distance between the central-hyoid and symphysis of the mandible (hyo-mental distance; HMD) and inclination of this line to the horizontal axis (hyo-mental angle; HMA) in neutrally positioned patients is investigated. Methods: HMA, HMD in MPS, and non-MPS were compared, and their correlation with height and weight were assessed. Results: 50 adult MPS patients (M = 32, F = 18, age range = 19–66 years; mean BMI = 26.8 kg/m²) of MPS I, II, III, IV, and VI were compared with 50 non-MPS (M = 25, F = 25; age range = 22–84 years; mean BMI = 26.5 kg/m²). Mean HMA in MPS was 25.72° (−10 to +50) versus 2.42° (−35 to +28) in non-MPS. Mean HMD was 46.5 (25.7–66) millimeters in MPS versus 41.8 (27–60.3) in non-MPS. HMA versus height and weight showed a moderate correlation (r = −0.4, p < 0.05) in MPS and no significant correlation (r < 0.4, p > 0.05) in non-MPS. HMD versus height and weight showed no correlation (r < 0.4, p > 0.05) in both groups. Conclusions: HMA seems more acute in MPS despite nearly the same HMD as non-MPS, signifying a high larynx, which may be missed by TMD.

Access to oral health care services for individuals with rare genetic diseases affecting skeletal development

OBJECTIVE

To identify factors associated with oral health care services for individuals with and without rare genetic diseases.

MATERIALS AND METHOD

A cross-sectional study was undertaken, with 140 individuals paired by sex and age (70 with rare genetic diseases and 70 without), aged between 3 and 27 years, and their parents. The sample was selected from two reference hospitals for patients with rare genetic diseases in southeastern Brazil. The parents completed a questionnaire on individual aspects and their child's medical/dental history. Participants who did and did not suffer from rare genetic diseases were examined for dental caries, malocclusion, dental anomalies, and oral hygiene. The theoretical model Directed Acyclic Graphs (DAG) was used to identify possible confounding variables in the association between rare diseases and access to dental care. Descriptive analyses and non-matched and matched logistic regression models (p < 0.05) were carried out.

RESULTS

The chance of individuals without rare genetic disease having access to oral health care service was 5.32 times higher (95% CI 2.35-12.01) than those with such conditions. Individuals who had not suffered upper respiratory tract infections had a 3.16 times greater chance of being in the group with access to oral health care service (95% CI 1.45-6.90).

CONCLUSION

Individuals with no rare genetic diseases and no history of upper respiratory tract infections had a greater chance of belonging to the group of individuals with access to a dental service. Individuals with rare genetic diseases have less access to oral health care.

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.

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.

AISF update on the diagnosis and management of adult-onset lysosomal storage diseases with hepatic involvement

Lysosomal storage diseases (LSDs) are a heterogeneous group of inherited disorders caused by loss-of-function mutations in genes encoding for lysosomal enzymes/proteins. The consequence is a progressive accumulation of substrates in these intracellular organelles, resulting in cellular and tissue damage. The overall incidence is about 1/8000 live births, but is likely underestimated. LSDs are chronic progressive multi-systemic disorders, generally presenting with visceromegaly, and involvement of the central nervous system, eyes, the skeleton, and the respiratory and cardiovascular systems. The age at onset and phenotypic expression are highly variable, according to the specific enzymatic defect and tissues involved, the residual activity, and the disease-causing genotype. Enzyme-replacement therapies and substrate-reduction therapies have recently become available, leading to the improvement in symptoms, disease progression and quality of life of affected individuals. Liver involvement and hepatosplenomegaly are frequent features of LSDs and a hallmark of adult-onset forms, frequently leading to medical attention. LSDs should therefore be considered in the differential diagnosis of liver disease with organomegaly. The present document will provide a short overview of adult-onset LSDs with hepatic involvement, highlighting the specificities and systemic manifestations of the ones most frequently encountered in clinical practice, which may hint at the correct diagnosis and the appropriate treatment.

Treating lysosomal storage disorders: What have we learnt?

The first enzyme replacement therapy (ERT) for a lysosomal storage disorder (LSD) was approved in 1991 and we now have more than 25 years of experience of treating patients with type 1 Gaucher disease. Because of the remarkable success of this therapy, enormous effort and resource has gone into developing other ERTs, for Gaucher (where three different enzyme preparations have now been approved) and for other LSDs. We now have more than 10 years of clinical experience in using ERT to treat Gaucher, Fabry, Pompe and MPS I, II, and VI. This article aims to assess the real-life experience of a selection of these innovative and expensive treatments to see if they have met the high expectations which were set for them when they launched.

Cochlear Implantation via the Transmeatal Approach in an Adolescent with Hunter Syndrome-Type II Mucopolysaccharidosis

Type II mucopolysaccharidosis (MPS II) commonly known as Hunter syndrome, is a rare X-linked lysosomal storage disorder caused by iduronate-2-sulfatase deficiency, which in turn causes otorhinolaryngological manifestations, including sensorineural hearing loss (SNHL). Previously, the median survival age of patients with MPS was approximately 13.4 years. However, in the era of enzyme replacement therapy and other multidisciplinary care modalities, the life expectancy has increased. Herein, we report a rare case of an adolescent with MPS II who underwent SNHL treatment with cochlear implantation (CI). Based on unexpected findings of mastoid emissary veins and overgrowth of the vessels around the temporal bone, CI was performed using the transmeatal approach instead of the conventional transmastoid method, to avoid damage to the vessels. The average hearing threshold after CI was 35 dB and no surgical complications were encountered. Adolescent MPS II may present vessel abnormalities, which can reduce the success rate of surgery. In patients with MPS II with SNHL, CI should be performed under careful monitoring of vessel overgrowth. Moreover, with regard to feasibility of CI in adolescent patients with MPS II with SNHL, surgical techniques such as the transmeatal approach should be selected based on adequate assessment of the case.

Neonatal Mass Urine Screening Approach for Early Detection of Mucopolysaccharidoses by UPLC-MS/MS

Mucopolysaccharidoses (MPSs) are lysosomal storage disorders caused by deficiencies of enzymes involved in the catabolism of glycosaminoglycans (GAGs). Various treatments such as enzyme replacement therapy and/or hematopoietic stem cell transplant are available for MPSs. Early initiation of treatment improves the outcome and delays the onset of symptoms, highlighting the need for newborn screening for MPSs. The main objective of this project was to devise and validate a multiplex urine filter paper method for GAG analysis using a tandem mass spectrometry (MS/MS) approach to screen newborns for MPSs. Eluted urine samples from 21-day-old newborns were evaporated and a methanolysis reaction was performed. Samples were resuspended and analyzed using a UPLC-MS/MS system. A one-minute chromatographic method allowed the absolute quantification of heparan sulfate (HS), dermatan sulfate (DS), and creatinine. Method validation revealed high precision (< 9% relative standard deviation) and accuracy (< 7% bias) for all analytes. The reference values normalized to creatinine obtained by the analysis of five hundred 21-day-old newborn urine samples were 34.6 +/-6.2 mg/mmol of creatinine and 17.3 +/-3.9 mg/mmol of creatinine for HS and DS, respectively. We present a rapid and efficient method for populational newborn urine screening using MS/MS, which could also be applied to high-risk screening.

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 IVA: systematic evidence- and consensus-based guidance

INTRODUCTION

Mucopolysaccharidosis (MPS) IVA or Morquio A syndrome is an autosomal recessive lysosomal storage disorder (LSD) caused by deficiency of the N-acetylgalactosamine-6-sulfatase (GALNS) enzyme, which impairs lysosomal degradation of keratan sulphate and chondroitin-6-sulphate. The multiple clinical manifestations of MPS IVA present numerous challenges for management and necessitate the need for individualised treatment. Although treatment guidelines are available, the methodology used to develop this guidance has come under increased scrutiny. This programme was conducted to provide evidence-based, expert-agreed recommendations to optimise management of MPS IVA.

METHODS

Twenty six international healthcare professionals across multiple disciplines, with expertise in managing MPS IVA, and three patient advocates formed the Steering Committee (SC) and contributed to the development of this guidance. Representatives from six Patient Advocacy Groups (PAGs) were interviewed to gain insights on patient perspectives. A modified-Delphi methodology was used to demonstrate consensus among a wider group of healthcare professionals with experience managing patients with MPS IVA and the manuscript was evaluated against the validated Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument by three independent reviewers.

RESULTS

A total of 87 guidance statements were developed covering five domains: (1) general management principles; (2) recommended routine monitoring and assessments; (3) disease-modifying interventions (enzyme replacement therapy [ERT] and haematopoietic stem cell transplantation [HSCT]); (4) interventions to support respiratory and sleep disorders; (5) anaesthetics and surgical interventions (including spinal, limb, ophthalmic, cardio-thoracic and ear-nose-throat [ENT] surgeries). Consensus was reached on all statements after two rounds of voting. 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 IVA 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.

Orthopaedic challenges for mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are a group of diseases characterized by abnormal accumulation of glycosaminoglycans (GAGs). Although there are differences among the various disease types, the osteoarticular system is always involved. The aim of the present study was to establish a framework for MPS-related orthopaedic manifestations and for their treatment. The authors, affiliated to three different Italian Orthopaedic Centres, report data taken from the literature reviewed in light of their accumulated professional experience. Bone alterations make up what is known as dysostosis multiplex, involving the trunk and limbs and with typical radiological findings. Joints are affected by pathological tissue infiltrations. The cervical spinal cord is involved, with stenosis and cervical and occipitocervical instability. In MPS there is a much higher incidence of scoliosis compared with healthy subjects without any particular distinctive feature. Kyphosis of the spine is more frequent and also more severe because of its possible neurological complications, and it is localized at the thoracolumbar level with a malformed vertebra at the top of the deformity. Evolving forms, and those associated with neurological damage, require anteroposterior spine fusion. The hip is invariably involved, with dysplasia affecting the femoral neck (coxa valga), the femoral epiphysis (loss of sphericity, osteonecrosis), and the femoral acetabulum which is flared. All these features explain the tendency to progressive hip migration. Genu valgum is often found (a deviation of the physiological axis with an obtuse angle opening laterally). This deformity is often localized at the proximal tibial metaphysis; it causes functional limitations and leads to an irregular erosion of the articular cartilage. In young patients who still have the growth plate, it is possible to execute a medial hemiepiphysiodesis, a temporary inhibition of cartilage growth, with progressive axis correction. In this paper, the characterisation of clinical features and the review of treatments are divided into separate sections based on the part of the body involved. The conclusions of each section are presented as a summary. One section discusses the high risk of anaesthesia-related complications requiring the collaboration of specifically trained personnel.

Spinal cord issues in adult patients with MPS: transition of care survey

PURPOSE

This study aims to raise awareness of the need for research and appropriate guidelines for managing spinal cord issues in adult patients with mucopolysaccharidosis (MPS) and transition of these patients from pediatric to adult care.

METHODS

Pediatric/adult neurosurgeons, orthopedic spine surgeons, and treating physicians with expertise in metabolic disorders and spinal cord issues were invited to complete a survey to assess their experience with spinal cord problems in MPS and their opinion on transitioning routes from pediatric to adult care.

RESULTS

Twenty specialists completed the survey; 16 had treated spinal cord issues in patients with MPS. Foramen magnum and cervical stenosis (87%), atlanto-axial instability (67%), and lumbar spine instability (33%) were the main spinal cord issues encountered; 28% had treated adult patients for one or more spinal cord issues. In 40% of cases, this concerned an intervention or procedures performed during childhood. The main specialist responsible for the care of adult patients with MPS differed considerably between institutions and included both pediatric and adult specialists (30% pediatric neurosurgeons, 10% pediatric spine orthopedic surgeons, 30% adult spine neurosurgeons, 20% general adult surgeons). The preferred option (> 50%) for the transition of care was an interdisciplinary team of pediatric and adult specialists.

CONCLUSIONS

Further work needs to be done to address problems of managing spinal cord issues in adult patients with MPS. Currently, the responsibility for the care of patients with MPS with spinal cord issues is inconsistent. The best strategy for transitioning these patients from pediatric to adult care is likely an interdisciplinary approach.

Mortality in patients with Sanfilippo syndrome

BACKGROUND

Sanfilippo syndrome (mucopolysaccharidosis type III; MPS III) is an inherited monogenic lysosomal storage disorder divided into subtypes A, B, C and D. Each subtype is characterized by deficiency of a different enzyme participating in metabolism of heparan sulphate. The resultant accumulation of this substrate in bodily tissues causes various malfunctions of organs, ultimately leading to premature death. Eighty-four, 24 and 5 death certificates of patients with Sanfilippo syndrome types A, B and C, respectively, were obtained from the Society of Mucopolysaccharide Diseases (UK) to better understand the natural course of these conditions, covering the years 1977-2007.

RESULTS

In Sanfilippo syndrome type A mean age at death (± standard deviation) was 15.22 ± 4.22 years, 18.91 ± 7.33 years for patients with Sanfilippo syndrome type B and 23.43 ± 9.47 years in Sanfilippo syndrome type C. Patients with Sanfilippo syndrome type A showed significant increase in longevity over the period of observation (p = 0.012). Survival rates of patients with Sanfilippo syndrome type B did not show a statistically significant improvement (p = 0.134). In Sanfilippo syndrome types A and B, pneumonia was identified as the leading cause of death.

CONCLUSIONS

The analysis of 113 death certificates of patients with Sanfilippo syndrome in the UK has demonstrated that the longevity has improved significantly in patients with Sanfilippo syndrome type A over a last few decades. The numbers of patients with Sanfilippo syndrome types B and C were too small to identify any significant trend changes for these groups. Respiratory tract infections, notably pneumonia, remain the leading cause of mortality in Sanfilippo syndrome types A and B. The extended lifespans of patients with Sanfilippo syndrome type A were achieved despite the lack of therapies to target the primary insult or pathophysiology of the disease. However, the mean age at death of these patients remains low when compared with the general population. Therefore, there is an urgent need for effective disease-specific therapies to be developed so that the quality of life and survival of patients with Sanfilippo syndrome can be improved.

The Carotid Intima-Media Thickness and Arterial Stiffness of Pediatric Mucopolysaccharidosis Patients Are Increased Compared to Both Pediatric and Adult Controls

Treatments for mucopolysaccharidoses (MPSs) have increased longevity, but cardiovascular disease causes mortality in a significant percentage of survivors. Markers must be developed to predict MPS cardiac risk and monitor efficacy of investigational therapies.MPS patients underwent carotid artery ultrasonography from which carotid intima-media thickness (cIMT) and three measures of arterial stiffness were calculated: carotid artery distensibility (cCSD), compliance (cCSC), and incremental elastic modulus (cIEM). MPS carotid measurements were compared to corresponding data from pediatric and adult healthy cohorts. 33 MPS patients (17 MPS I, 9 MPS II, 4 MPS IIIA, and 3 MPS VI; mean age 12.5 ± 4.7 years), 560 pediatric controls (age 13.1 ± 4.0 years), and 554 adult controls (age 39.2 ± 2.2 years) were studied. Age and sex-adjusted aggregate MPS cIMT (0.56 ± 0.05 mm) was significantly greater than both pediatric (+0.12 mm; 95% CI +0.10 to +0.14 mm) and adult (+0.10 mm; 95% CI +0.06 to +0.14 mm) control cohorts; similar findings were observed for all MPS subtypes. Mean MPS cIMT approximated the 80th percentile of the adult cohort cIMT. MPS patients also demonstrated significantly increased adjusted arterial stiffness measurements, evidenced by reduced cCSD, cCSC, and increased cIEM, compared to pediatric and adult control cohorts. Regardless of treatment, MPS patients demonstrate increased cIMT and arterial stiffness compared to healthy pediatric and adult controls. These data suggest that relatively young MPS patients demonstrate a “structural vascular age” of at least 40 years old.

Mucopolysaccharidoses seen in adults in rheumatology

Mucopolysaccharidoses are a group of rare lysosomal storage diseases including a great number of polymorph syndromes, each being related to a particular mutation responsible for a deficiency of glycosaminoglycan degrading enzymes, leading to an accumulation of glycosaminoglycans in tissues. Many of them are diagnosed in children or teenagers and have a severe prognosis because of organ failure, and are consequently usually not seen by the adult rheumatologist. However, some of them have a more progressive presentation, with musculoskeletal symptoms at the forefront and a lifespan that nearly reaches that of the general population. These milder forms are more likely to be diagnosed in adults, in patients who have suffered for years and sometimes even decades with unrecognized mucopolysaccharidosis. Indeed, they can sometimes mimic inflammatory rheumatic disorders, and therefore be misdiagnosed for a long time. Recognition and diagnosis of these attenuated forms can be a real challenge as they lead to moderate and/or nonspecific symptoms such as joint pain or stiffness. Hence, rheumatologists should know about them. Early diagnostic is essential since specific treatment, like enzyme replacement therapy, is now available for some subtypes and might, if given early, slow down the development of tissue damage, which is unfortunately irreversible. This article provides the opportunity to review the main clinical and radiographic features, the diagnostic strategy and the update of management, which should be multidisciplinary and led by an experienced physician in a reference centre. The contribution of the rheumatologist is important to ensure symptom control and prevent complications.