Orthopedic management of the extremities in patients with Morquio A syndrome

A Rare Case of Dyggve-Melchior-Clausen Syndrome: A Case Report

Dyggve-Melchior-Clausen (DMC) disease, also known as DMC syndrome, is a rare, progressive genetic disorder that is characterized by skeletal and intellectual abnormalities. The case report involves a four-year-old male child presenting with marked short stature, intellectual disability, coarse facies, and microcephaly. Initial investigations, including blood tests and radiological evaluations, prompted further genetic testing via whole-exome sequencing. This identified a homozygous mutation in the Dymeclin (DYM) gene, implicating DMC disease. The condition usually poses diagnostic challenges due to overlapping clinical features with Morquio syndrome. This case highlights the importance of a comprehensive diagnostic approach and genetic testing in elucidating the underlying genetic etiology of complex presentations in pediatric patients.

Clinical Characteristics of a Patient with Mucopolysaccharidosis Type IVA (Morquio Syndrome)

Mucopolysaccharidosis (MPS) type IVA (Morquio syndrome) is a hereditary lysosomal storage disease caused by deficiency of N-acetylglucosamine-6-sulfate sulfatase. This enzyme deficiency leads to specific glycosaminoglycans (keratan sulfate and chondroitin-6-sulfate) accumulation mainly in the bone and cartilage tissues, as well as in the cardiovascular, respiratory systems, and visual systems. Patients with MPS IVA look healthy at birth, however, they develop typical spine deformities (kyphoscoliosis), pectus carinatum, wrists hypermobility with decreased muscle strength and loss of fine motor skills, valgus deformation of lower limbs during the first years of life. Pathological changes in cardiovascular and respiratory systems, visual and acoustic analyzers can be revealed. Early diagnosis of the disease is crucial for timely initiation of enzyme replacement therapy. Thus, low incidence of the disease and its heterogeneous clinical picture complicates diagnosis. Consequently, patients with MAS IVA often become severely disabled as early as adolescence. Patients with severe form and without treatment die before the age of 30 due to complications of respiratory system diseases, valvular heart apparatus involvement, and cervical myelopathy.

Dental Considerations for the Treatment of Patients with Morquio Syndrome

Aim

Morquio syndrome, also called Mucopolysaccharidosis IV (MPS IV), is a rare autosomal recessive metabolic lysosomal disorder that results in the deposition of glycosaminoglycans (GAGs) in various tissues and organs, resulting in an array of signs and symptoms. The aim of the study was to systematically record the clinical features with a special emphasis on oral manifestations of patients diagnosed with MPS IV and asses the dental treatment implications of the disease manifestations.

Materials and methods

A cross-sectional study was conducted on patients diagnosed with MPS IV (n = 26). A complete clinical and oral examination was done and the findings were systemically recorded.

Results

The study showed that the patients diagnosed with MPS IV have multiple treatment challenges owing to the range of disease manifestations. Furthermore, they have higher oral health care needs because of the anatomical and pathological changes.

Conclusion and clinical significance

Dental professionals must be aware of the implications of the disease manifestation and their accompanying challenges while treating patients with MPS IV. The oral health needs are higher for these patients and regular dental evaluation and treatment must be incorporated into their health care regimen.

How to cite this article

Vinod A, Raj SN, Anand A, et al. Dental Considerations for the Treatment of Patients with Morquio Syndrome. Int J Clin Pediatr Dent 2022;15(6):707-710.

Assessment of IL-1β, IL-6, TNF-α, IL-8, and CCL 5 levels in newly diagnosed Saudi patients with rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disorder which mainly affects small joints, occurs most commonly in middle-aged adults, and can be fatal in severe cases. The exact etiology of RA remains unknown. However, uncontrolled expression of pro-inflammatory cytokines and chemokines can contribute to the pathogenesis of RA.

AIM

In the current study, we assessed the potential of serum concentrations of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, IL-8, and C-C motif chemokine ligand (CCL)5 as early predictive markers for RA.

METHODS

In addition to clinical examination, blood samples were collected from 100 Saudi patients recently diagnosed with early RA for basic and serological tests, including rheumatoid factor (RF), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). Sera of 32 healthy individuals were used as controls. Specific enzyme-linked immunosorbent assay was used to quantify the serum IL-1β, IL-6, TNF-α, IL-8, and CCL5 levels in the samples.

RESULTS

Our results indicated that RF, CRP, and ESR levels were higher in RA patients compared to controls. Furthermore, serum levels of IL-1β, IL-6, IL-8, and CCL5, but not TNF-α, significantly increased in RA patients compared to controls.

CONCLUSION

Overall, the findings suggested that IL-1β, IL-6, IL-8, and CCL5 can be used as biomarkers in the early diagnosis of RA.

RNA analysis of the GALNS transcript reveals novel pathogenic mechanisms associated with Morquio syndrome A

Morquio syndrome A (Mucopolysaccharidosis IVA, MPS IVA) is an autosomal recessive lysosomal storage disorder caused by deficiency of N-acetyl-galactosamine-6-sulfatase (GALNS) which catabolizes the glycosaminoglycans (GAG), keratan sulfate and chondroitin-6-sulfate. Homozygous or compound heterozygous pathogenic variants in the GALNS result in the deficiency of the enzyme and consequent GAG accumulations. DNA sequence and copy number analysis of the GALNS coding region fails to identify biallelic causative pathogenic variants in up to 15% of patients with Morquio syndrome A. RNA transcript analysis was performed to identify pathogenic alterations in two unrelated families with Morquio syndrome A in whom a single heterozygous or no pathogenic alteration was detected by standard analysis of the GALNS gene. RNA sequencing and quantitative expression analysis identified the overabundance of an aberrant GALNS transcript isoform and a reduction of the clinically relevant isoform (NM_000512.4) in the Morquio syndrome A patients from both families. The aberrant isoform (ENST00000568613.1) was produced by alternative splicing and contained intronic sequence that was likely a cryptic exon predicted to result in a reading frame shift and generation of a premature termination codon. These findings indicated that the aberrant splicing is likely the novel molecular defect in our patients. RNA transcript analysis could be useful to identify pathogenic alterations and increase the yield of molecular diagnosis in patients with Morquio syndrome A whose genetic variants are not found by standard sequencing or gene dosage analysis.

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.

Evaluation of Gait Pattern and Lower Extremity Kinematics of Children with Morquio Syndrome (MPS IV)

Morquio syndrome (mucopolysaccharidosis IV/MPS IV) is a genetic disorder leading to skeletal abnormalities and gait deviations. Research on the gait patterns and lower extremity physical characteristics associated with skeletal dysplasia in children with MPS IV is currently limited. This research aimed to provide baseline gait patterns and lower limb skeletal alignment of children with MPS IV utilizing three-dimensional instrumented gait analysis. This Institutional Review Board-approved retrospective study evaluates the kinematics of the lower extremities of children with MPS IV during gait, comparing them with an age-matched group of typically developing children. Thirty-three children with MPS IV were included (8.6 ± 4.0 years old). Children with MPS IV walk with increased anterior pelvic tilt, knee valgus, knee flexion, external tibial torsion, and reduced walking speed and stride length (p < 0.001). Multiplanar abnormal alignment results in abnormal knee moments (p < 0.001). Limited correlations exist (r = 0.69–0.28) between dynamic three-dimensional measurements of knee varus/valgus and rotational alignment and traditional static two-dimensional measures (physical examination or radiographs) suggesting the possibility of knee instability during gait and the benefits of dynamic assessment.

Intraoperative Neurological Monitoring in Lower Limb Surgery for Patients With Mucopolysaccharidoses

BACKGROUND

There are reports of spinal cord injury (SCI) occurring after lower extremity (LE) surgery in children with mucopolysaccharidoses (MPS). Intraoperative neurological monitoring (IONM) has been adopted in some centers to assess real-time spinal cord function during these procedures. The aim of this investigation was to review 3 specialty centers' experiences with MPS patients undergoing LE surgery. We report how IONM affected care and the details of spinal cord injuries in these patients.

METHODS

All pediatric MPS patients who underwent LE surgery between 2001 and 2018 were reviewed at 3 children's orthopaedic specialty centers. Demographic and surgical details were reviewed. Estimated blood loss (EBL), surgical time, positioning, use of IONM, and changes in management as a result of IONM were recorded. Details of any spinal cord injuries were examined in detail.

RESULTS

During the study period, 92 patients with MPS underwent 252 LE surgeries. IONM was used in 83 of 252 (32.9%) surgeries, and intraoperative care was altered in 17 of 83 (20.5%) cases, including serial repositioning (n=7), aggressive blood pressure management (n=6), and abortion of procedures (n=8). IONM was utilized in cases with larger EBL (279 vs. 130 mL) and longer operative time (274 vs. 175 min) compared with procedures without IONM. Three patients without IONM sustained complete thoracic SCI postoperatively, all from cord infarction in the upper thoracic region. These 3 cases were characterized by long surgical time (328±41 min) and substantial EBL (533±416 mL or 30.5% of total blood volume; range, 11% to 50%). No LE surgeries accompanied by IONM experienced SCI.

CONCLUSIONS

Patients with MPS undergoing LE orthopaedic surgery may be at risk for SCI, particularly if the procedures are long or are expected to have large EBL. One hypothesis for the etiology of SCI in this setting is hypoperfusion of the upper thoracic spinal cord due to prolonged intraoperative or postoperative hypotension. IONM during these procedures may mitigate the risk of SCI by identifying real-time changes in spinal cord function during surgery, inciting a change in the surgical plan.

LEVEL OF EVIDENCE

Level III-retrospective comparative series.

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.

Hip morphology in mucopolysaccharidosis type IVA through radiograph, magnetic resonance imaging and arthrogram assessment

PURPOSE

This study examined the hip morphology of paediatric patients with mucopolysaccharidosis (MPS) type IVA (MPS IVA).

METHODS

This was a retrospective chart review of 42 hips in 21 children with MPS IVA. Pelvic radiographs and magnetic resonance imaging (MRI) scans of 42 hips and arthrograms of 13 hips were analysed. The bony, cartilaginous and labral coverage of the acetabulum was determined by acetabular index (AI), centre edge angle (CEA) and femoral head coverage (FHC).

RESULTS

The mean age at the time of radiography was 66.3 ± 21.7 months. The bony, cartilaginous and labral AI in the MRI assessment were 36.3 ± 5.3, 18.3 ± 4.7 and 12.1 ± 4.6 degrees, respectively. The inter-class correlation coefficients (ICCs) for the bony AI, CEA and FHC measurements on radiographs and MRI were 0.936, 0.879 and 0.810, respectively. In the MRI assessment, labrum in 12 of 42 hips appeared as a regular triangle, and it was flat on 30/42 hips. The average arthrographic AI (AAI) was 11.1 ± 2.7 degrees. The ICCs value of AAI versus cartilaginous and labral AI on MRI indicates good agreement but higher in labral AI.

CONCLUSION

Hips in MPS IVA exhibited obvious cartilage and labrum compensation in response to abnormal ossification of bony acetabulum. Cartilage in MPS IVA hip increases the thickness in the longitudinal direction, while the labrum becomes flatten in the horizontal direction. The AAI may represent intraoperative labrum coverage. The femora-acetabular harmony is difficult to determine using radiography only, and pre-operative MRI and an intraoperative arthrogram are very important in a hip assessment in MPS IVA.

Pathophysiology of Hip Disorders in Patients with Mucopolysaccharidosis IVA

Patients with mucopolysaccharidoses IVA (MPS IVA) have a progressive accumulation of the specific glycosaminoglycans (GAGs): chondroitin-6-sulfate (C6S) and keratan sulfate (KS), leading to the degeneration of the cartilage matrix and its connective tissue perturbing the regular microarchitecture of cartilage and successively distorting bone ossification and growth. Impaired cartilage quality and poor bone mineralization lead to serious hip disorders in MPS IVA patients. Although hip dysplasia is seen widely in musculoskeletal abnormality of this disorder, the pathophysiology of the hip bone and cartilage morphology in these patients remains unclear. Until now, no systemic study of the hip joints in MPS IVA has been reported by using the combined images of plain film radiographs (PFR) and Magnetic Resonance Imaging (MRI). This study aimed to assess the bony and cartilaginous features of hip joints and to explore the potentially related factors of femoral head osteonecrosis (FHN) and hip subluxation/dislocation in patients with MPS IVA. Hip joints in MPS IVA patients were retrospectively reviewed, based on the findings of PFR and MRI data from 2014 to 2019. Demographic information was also collected and analyzed with imaging measurements. A total of 19 patients (eight boys and 11 girls) were recruited, and 38 hip joints in these patients were examined. Eleven patients (57.9%) had FHN. FHN patients were statistically compared with those without FHN. Correlations between cartilaginous femoral head coverage (CFHC) and acetabular index (AI), cartilaginous AI (CAI), or neck-shaft angle (NSA) were investigated in patients with hip subluxation or dislocation. The greater cartilaginous coverage of the hips than their osseous inherency was observed. Significant correlation was observed between CFHC and AI (r =-0.351, p = 0.049) or CAI (r =-0.381, p = 0.032). Severe subluxations or dislocations were more likely to be present in those with more dysplastic bony and cartilaginous hips. In conclusion, our study provides the first systemic description of bony and cartilaginous characteristics in the hip morphology of MPS IVA patients. We have demonstrated that plain radiography alone leads to a misunderstanding of hip morphology and that MRI measurements with PFR are an essential tool to evaluate the 'true' characterization of hips for MPS IVA patients.

Assessing the impact of the five senses on quality of life in mucopolysaccharidoses

Background

The mucopolysaccharidoses (MPSs) are lysosomal storage disorders associated with progressive multi-organ and skeletal abnormalities. Clinical manifestations can affect each of the five senses: hearing, vision, smell, taste, and touch.

Main body of the abstract

On 24–26 May 2018, 46 specialists with expertise in managing symptoms of MPS and experts specialized in evaluating and managing impairments in each one of the five senses gathered in Lisbon, Portugal at the “MPS & the five senses” meeting to discuss how loss of one or multiple senses can affect activities of daily living (ADL) and quality of life (QoL) in MPS patients and best practices in evaluating and managing the loss of senses in these individuals. The meeting confirmed that MPS can affect the senses considerably, but how these impairments affect ADL and overall QoL from a patient’s perspective remains unclear. A better insight may be achieved by prospectively collecting patient-reported outcome (PRO) data internationally in a standardized way, using a standard battery of tools. To identify relevant PRO tools, a systematic literature review and a selection of existing published questionnaires, focused on adults with no intellectual delay, were performed after the meeting. The search strategy identified 33 PRO tools for hearing, 30 for speech, 125 for vision, 49 for touch (including pain and upper limb function), and 15 for smell/taste. A further selection was made based on several criteria, including applicability/relevance for MPS, applicability in different countries (languages)/cultures, availability in English, ease of use, validation, and normative data, resulting in a final set of 11 tools. In addition to these sense-specific PRO tools, a general QoL tool, the EuroQol (EQ)-5D-5 L, was selected to assess overall QoL and reveal coping behaviors.

Short conclusion

MPS can affect each of the five senses, but current knowledge on the impact of sense impairments on QoL/ADL in MPS patients remains limited. Collection of data in a standardized fashion using sense-specific patient-reported outcome tools and a general QoL tool may fill the current knowledge gap.

Mucopolysaccharidosis IVA: Diagnosis, Treatment, and Management

Mucopolysaccharidosis type IVA (MPS IVA, or Morquio syndrome type A) is an inherited metabolic lysosomal disease caused by the deficiency of the N-acetylglucosamine-6-sulfate sulfatase enzyme. The deficiency of this enzyme accumulates the specific glycosaminoglycans (GAG), keratan sulfate, and chondroitin-6-sulfate mainly in bone, cartilage, and its extracellular matrix. GAG accumulation in these lesions leads to unique skeletal dysplasia in MPS IVA patients. Clinical, radiographic, and biochemical tests are needed to complete the diagnosis of MPS IVA since some clinical characteristics in MPS IVA are overlapped with other disorders. Early and accurate diagnosis is vital to optimizing patient management, which provides a better quality of life and prolonged life-time in MPS IVA patients. Currently, enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT) are available for patients with MPS IVA. However, ERT and HSCT do not have enough impact on bone and cartilage lesions in patients with MPS IVA. Penetrating the deficient enzyme into an avascular lesion remains an unmet challenge, and several innovative therapies are under development in a preclinical study. In this review article, we comprehensively describe the current diagnosis, treatment, and management for MPS IVA. We also illustrate developing future therapies focused on the improvement of skeletal dysplasia in MPS IVA.

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.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Electronic supplementary material

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

Hip Dysplasia in Mucopolysaccharidosis Type IVA (Morquio A Syndrome) Treated by Proximal Femoral Valgization Osteotomy: A Case Report

Introduction

Morquio A syndrome or mucopolysaccharidosis type IVA (MPS IVA) is a progressive lysosomal storage disorder caused by an N-acetylgalactosamine-6-sulfatase deficiency. The abnormal metabolism of glycosaminoglycans among other medical problems leads to various skeletal disorders caused by a dysfunction of endochondral ossification of epiphyseal cartilage. Severe hip dysplasia is common and can lead to pain and impaired mobility.

Case Report

We report on a 15-year-old girl suffering from MPS IVA. At the age of 5 years, hip pain and a reduced walking distance were described for the 1sttime. At the age of 9 years, acetabulofemoral dysplasia associated with genuavalga was diagnosed. After pre-operative assessment of the hips including plain radiographs, magnetic resonance imaging, and arthrography with dynamic testing a valgization osteotomy of the proximal femur in combination with a shelf acetabuloplasty was performed. The patient was followed for 6 years with a stable hip joint and without any sign of redislocation.

Conclusion

Some treatment strategies of hip dysplasia in patients with MPS IVA are described in the literature. The techniques used for congenital hip dysplasia, varisation of the femur in combination with Pemberton, Salter, or shelf acetabuloplasty, are widely reported. Nevertheless, resubluxations were described in some cases. The well-known surgical procedure with valgization of the proximal femur is not reported in literature for MPS IVA patients. In our opinion, dynamic testing with arthrography should strongly be considered for this particular problem before surgical intervention. Pathology-related decisions should be made under consideration of the different surgical techniques.

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

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

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.

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

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

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

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

Does orthopaedic surgery improve quality of life and function in patients with mucopolysaccharidoses?

PURPOSE

Mucopolysaccharidoses (MPS) are a group of rare lysosomal storage disorders associated with involvement of multiple organs along with a generalised skeletal dysplasia. Both haematopoetic stem cell transplant and enzyme replacement therapy have improved the outlook for patients while surgery remains high-risk and there is little information on clinical or functional outcome to justify many of the surgical procedures performed. This paper aims to summarise the orthopaedic surgical procedures in MPS patients for which quality of life (QoL) and functional data are available and to describe additional QoL and functional measurement tools of relevance to the assessment of orthopaedic outcomes in MPS.

METHODS

We reviewed the available literature to look for reported outcomes of orthopaedic surgery to lower and upper limbs and the spine. In addition, we describe the general and MPS-specific health measures that might be of relevance to the orthopaedic surgeon.

RESULTS

There is some evidence in the literature that orthopaedic surgery may improve QoL and function in some specific aspects of the MPS condition (in relation to genu valgum, carpal tunnel syndrome and trigger digits); however, the literature is sparse and consists of level 4/5 studies only. Further studies of these conditions should include QoL and functional assessment in order to confirm or refute these reports. In other areas (spine and hip), outcomes are judged largely on radiographic appearances with little clinical correlation and short follow-up; however, one long-term study of function following hip dysplasia surgery suggests poor outcomes. Anaesthetic morbidity/mortality is not insignificant in these complex patients with multi-organ involvement. Careful assessment is required, particularly when there is neurological involvement.

CONCLUSIONS

Orthopaedic surgeons involved with MPS patients should be encouraged to use and report measures of QoL and function with respect to musculoskeletal manifestations and response to surgery, recognising that such assessments in these complex and challenging patients may require a multidisciplinary approach.

A long term follow-up study of the development of hip disease in Mucopolysaccharidosis type VI

Hip problems in Mucopolysaccharidosis type VI (MPS VI) lead to severe disability. Lack of data on the course of hip disease in MPS VI make decisions regarding necessity, timing and type of surgical intervention difficult. We therefore studied the development of hip pathology in MPS VI patients over time. Data were collected as part of a prospective follow-up study. Standardized supine AP pelvis and frog leg lateral radiographs of both hips were performed yearly or every 2years. Image assessment was performed quantitatively (angle measurements) and qualitatively (hip morphology). Clinical burden of hip disease was evaluated by physical examination, six minute walking test (6MWT) and a questionnaire assessing pain, wheelchair-dependency and walking distance. A total of 157 pelvic radiographs of 14 ERT treated MPS VI patients were evaluated. Age at first image ranged from 2.0 to 21.1years. Median follow up duration was 6.8years. In all patients, even in the youngest, the acetabulum and os ilium were dysplastic. Coverage of the femoral head by the acetabulum improved over time, but remained insufficient. While the femoral head appeared normal in the radiographs at young age, the ossification pattern became abnormal in all patients over time. In all patients the distance covered in the 6MWT was reduced (median Z scores -3.3). Twelve patients had a waddling gait. Four patients were partially wheelchair-dependent and ten patients had limitations in their maximum walking distance. In conclusion, clinically significant hip abnormalities develop in all MPS VI patients from very early in life, starting with deformities of the os ilium and acetabulum. Femoral head abnormalities occur later, most likely due to altered mechanical forces in combination with epiphyseal abnormalities due to glycosaminoglycan storage. The final shape and angle of the femoral head differs significantly between individual MPS VI patients and is difficult to predict.

Mucopolysaccharidosis IVA and glycosaminoglycans

Mucopolysaccharidosis IVA (MPS IVA; Morquio A: OMIM 253000) is a lysosomal storage disease with an autosomal recessive trait caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase. Deficiency of this enzyme leads to accumulation of specific glycosaminoglycans (GAGs): chondroitin-6-sulfate (C6S) and keratan sulfate (KS). C6S and KS are mainly produced in the cartilage. Therefore, the undegraded substrates are stored primarily in cartilage and in its extracellular matrix (ECM), leading to a direct impact on cartilage and bone development, and successive systemic skeletal dysplasia. Chondrogenesis, the earliest phase of skeletal formation, is maintained by cellular interactions with the ECM, growth and differentiation factors, signaling pathways, and transcription factors in a temporal-spatial manner. In patients with MPS IVA, the cartilage is disrupted at birth as a consequence of abnormal chondrogenesis and/or endochondral ossification. The unique skeletal features are distinguished by a disproportional short stature, odontoid hypoplasia, spinal cord compression, tracheal obstruction, pectus carinatum, kyphoscoliosis, platyspondyly, coxa valga, genu valgum, waddling gait, and laxity of joints. In spite of many descriptions of these unique clinical features, delay of diagnosis still happens. The pathogenesis and treatment of systemic skeletal dysplasia in MPS IVA remains an unmet challenge. In this review article, we comprehensively describe historical aspect, property of GAGs, diagnosis, screening, pathogenesis, and current and future therapies of MPS IVA.

Guided growth may not be the best option for knee valgus deformity in adolescent patients with Morquio-A

INTRODUCTION

Valgus deformity in knees is a common concern in Morquio-A patients, preceding premature arthrosis and pain leading to walking disability and loss of ambulatory status. Treatment alternative is the guided growth, but this is sometimes not applied on time. Due to short height reached on these patients, not all will benefit from guided growth surgery.

PURPOSE

The purpose of this study is to describe early results of physeal osteotomy for acute valgus correction in adolescent patients and those almost at height peak to achieve alignment.

METHODS

We perform the osteotomy in four knees of 10- and 14-year-old patients, fixed with Kirschner wires, and allow early weight bearing. This is compared with one patient who was managed by guided growth.

RESULTS

The average acute correction osteotomy was 39 degrees with intermalleolar distance of 350 and 240 mm. At final follow-up, this measure was reduced to 70 and 20 mm, respectively, with clinical valgus of 4° and 2°. For the patient with guided growth, she was operated at 10.2 years old and 36 months in follow-up; preoperative valgus was 28/24° with intermalleolar distance of 140 mm. At the end of follow-up, this distance was increased to 150 mm with clinical valgus of 18/22°. During this follow-up, none of the patients lost ambulatory status. As a part of multi-organic disease progression, none of the three patients completed the 6-min walking test at final follow-up.

CONCLUSIONS

This physeal osteotomy is a feasible and optimal option to achieve acute valgus correction on severe deformity when there is not enough remaining growth on adolescent Morquio-A patients, and may help reduce arthritis progression in adjacent joints.

Unique medical issues in adult patients with mucopolysaccharidoses

The mucopolysaccharidoses are a group of inherited metabolic diseases caused by deficiencies in enzymes involved in the sequential degradation of glycosaminoglycans (GAGs) leading to substrate accumulation in various tissues and organs. GAG accumulation can cause growth retardation and progressive damage to respiratory, cardiovascular, musculoskeletal, nervous, gastrointestinal, auditory, and visual systems. In the past, few people with severe phenotypic mucopolysaccharidosis (MPS) reached adulthood. However, better methods for diagnosis, multi-disciplinary care, and new therapies have extended lifespan, leading to an increasing number of patients surviving beyond childhood. The growing number of adult MPS patients poses significant challenges for clinicians who may not be familiar with the clinical manifestations of MPS. In addition, as new interventions have changed the natural history of these disorders, it is difficult to anticipate both the impact on life expectancy and other complications that may occur as these patients age. Because the MPS disorders are multi-organ diseases, their management requires a coordinated multi-disciplinary approach. Here we discuss the unique pattern of medical issues and multi-organ involvement in adult patients with MPS and identify the challenges that are associated with management of MPS. This review is based on information from an expert investigator meeting with MPS specialists held October 2-4, 2014 in Dublin, Ireland, as well as on current literature searches focusing on MPS and adults.

Current therapies for Morquio A syndrome and their clinical outcomes

INTRODUCTION

Morquio A syndrome is characterized by a unique skeletal dysplasia, leading to short neck and trunk, pectus carinatum, laxity of joints, kyphoscoliosis, and tracheal obstruction. Cervical spinal cord compression/inability, a restrictive and obstructive airway, and/or bone deformity and imbalance of growth, are life-threatening to Morquio A patients, leading to a high morbidity and mortality. It is critical to review the current therapeutic approaches with respect to their efficacy and limitations.

AREAS COVERED

Patients with progressive skeletal dysplasia often need to undergo orthopedic surgical interventions in the first two decades of life. Recently, we have treated four patients with a new surgery to correct progressive tracheal obstruction. Enzyme replacement therapy (ERT) has been approved clinically. Cell-based therapies such as hematopoietic stem cell therapy (HSCT) and gene therapy are typically one-time, permanent treatments for enzyme deficiencies. We report here on four Morquio A patients treated with HSCT approved in Japan and followed for at least ten years after treatment. Gene therapy is under investigation on mouse models but not yet available as a therapeutic option.

EXPERT OPINION

ERT and HSCT in combination with surgical intervention(s) are a therapeutic option for Morquio A; however, the approach for bone and cartilage lesion remains an unmet challenge.

Activity of daily living for Morquio A syndrome

The aim of this study was to evaluate the activity of daily living (ADL) and surgical interventions in patients with mucopolysaccharidosis IVA (MPS IVA). The factor(s) that affect ADL are age, clinical phenotypes, surgical interventions, therapeutic effect, and body mass index. The ADL questionnaire comprises three domains: "Movement," "Movement with cognition," and "Cognition." Each domain has four subcategories rated on a 5-point scale based on the level of assistance. The questionnaire was collected from 145 healthy controls and 82 patients with MPS IVA. The patient cohort consisted of 63 severe and 17 attenuated phenotypes (2 were undefined); 4 patients treated with hematopoietic stem cell transplantation (HSCT), 33 patients treated with enzyme replacement therapy (ERT) for more than a year, and 45 untreated patients. MPS IVA patients show a decline in ADL scores after 10years of age. Patients with a severe phenotype have a lower ADL score than healthy control subjects, and lower scores than patients with an attenuated phenotype in domains of "Movement" and "Movement with cognition." Patients, who underwent HSCT and were followed up for over 10years, had higher ADL scores and fewer surgical interventions than untreated patients. ADL scores for ERT patients (2.5years follow-up on average) were similar with the-age-matched controls below 10years of age, but declined in older patients. Surgical frequency was higher for severe phenotypic patients than attenuated ones. Surgical frequency for patients treated with ERT was not decreased compared to untreated patients. In conclusion, we have shown the utility of the proposed ADL questionnaire and frequency of surgical interventions in patients with MPS IVA to evaluate the clinical severity and therapeutic efficacy compared with age-matched controls.

Evaluation of the Child with Short Stature

Orthopedic surgeons frequently encounter short statured patients. A systematic approach is needed for proper evaluation of these children. The differential diagnosis includes both proportionate and disproportionate short stature types. A proper history and physical examination and judicious use of plain film radiography will establish the diagnosis in most cases. In addition to the orthopedic surgeon, most of these patients will also be evaluated by other specialists, including endocrinologists and geneticists. This article provides an overview of the evaluation of the child with short stature and offers several illustrative examples.

Elosulfase Alfa: a review of its use in patients with mucopolysaccharidosis type IVA (Morquio A syndrome)

Elosulfase alfa (Vimizim(®)) is a recombinant form of the human lysosomal enzyme N-acetylgalactosamine-6-sulfatase (GALNS) that is lacking in patients with mucopolysaccharidosis type IVA (MPS IVA; Morquio A syndrome). It is the first, and currently only, disease-specific treatment option for this very rare, progressively degenerative, autosomal-recessive lysosomal storage disorder. Enzyme replacement therapy with elosulfase alfa aims to restore GALNS activity, thereby preventing the accumulation of keratan sulfate (KS) and chondroitin-6-sulfate in lysosomal compartments of cells that results in the clinical manifestations of MPS IVA. In clinical trials in children and adults with MPS IVA, intravenous elosulfase alfa 2 mg/kg/week provided significant and sustained improvements in urinary levels of KS (a pharmacodynamic biomarker for the disease). In the key placebo-controlled, 24-week, phase 3 trial in patients with MPS IVA aged ≥5 years, elosulfase alfa 2 mg/kg/week significantly improved endurance [least squares mean placebo-adjusted change from baseline in 6-min walk test distance 22.5 m (95 % CI 4.0-40.9)]. Infusion-associated reactions, the primary tolerability issue associated with elosulfase alfa, are generally mild to moderate in severity, self-limiting, and manageable. In the absence of a cure, GALNS enzyme replacement therapy with elosulfase alfa is an important achievement in the treatment of MPS IVA.

Longitudinal analysis of endurance and respiratory function from a natural history study of Morquio A syndrome

OBJECTIVES

Baseline data from the Morquio A Clinical Assessment Program (MorCAP) revealed that individuals with Morquio A syndrome show substantial impairment in multiple domains including endurance and respiratory function (Harmatz et al., Mol Genet Metab, 2013). Here, 1- and 2-year longitudinal endurance and respiratory function data are presented.

METHODS

Endurance was assessed using the 6-minute walk test (6MWT) and the 3-minute stair climb test (3MSCT). Respiratory function was evaluated by measuring forced vital capacity (FVC) and maximum voluntary ventilation (MVV). Data were analyzed using repeated measures ANCOVA models. Annualized estimates of change were determined using model estimates and interpolation.

RESULTS

353, 184, and 78 subjects were assessed at Year 0 (baseline), Year 1, and Year 2, respectively. The overall annualized estimate of change (SE) in 6MWT distance was -4.86±3.25m; a larger decline of -6.84±5.38m was observed in the subset of subjects meeting the inclusion/exclusion criteria of the Phase 3 clinical trial of elosulfase alfa (≥5years of age with baseline 6MWT distance ≥30 and ≤325m). In contrast, little change (-0.14±0.60stairs/min) was observed in 3MSCT. Annualized changes (SE) in FVC and MVV were 2.44±0.68% and 1.01±2.38%, respectively. FVC and MVV increased in patients aged ≤14years, but decreased in older patients.

CONCLUSIONS

The natural history of Morquio A syndrome is characterized by progressive impairment of endurance as measured by the 6MWT. Longitudinal trends in FVC and MVV showing increase in younger patients, but decrease in older patients, are likely to be influenced by growth. Changes in 6MWT may represent a sensitive measure of disease progression in ambulatory Morquio A patients.

International guidelines for the management and treatment of Morquio A syndrome

Morquio A syndrome (mucopolysaccharidosis IVA) is a lysosomal storage disorder associated with skeletal and joint abnormalities and significant non-skeletal manifestations including respiratory disease, spinal cord compression, cardiac disease, impaired vision, hearing loss, and dental problems. The clinical presentation, onset, severity and progression rate of clinical manifestations of Morquio A syndrome vary widely between patients. Because of the heterogeneous and progressive nature of the disease, the management of patients with Morquio A syndrome is challenging and requires a multidisciplinary approach, involving an array of specialists. The current paper presents international guidelines for the evaluation, treatment and symptom-based management of Morquio A syndrome. These guidelines were developed during two expert meetings by an international panel of specialists in pediatrics, genetics, orthopedics, pulmonology, cardiology, and anesthesia with extensive experience in managing Morquio A syndrome. © 2014 The Authors. American Journal of Medical Genetics Part A published by Wiley Periodicals, Inc.

Paraplegia after epidural-general anesthesia in a Morquio patient with moderate thoracic spinal stenosis

PURPOSE

We describe an instance in which complete paraplegia was evident immediately postoperatively after apparently uneventful lumbar epidural-general anesthesia in a patient with Morquio Type A syndrome (Morquio A) with moderate thoracic spinal stenosis.

CLINICAL FEATURES

A 16-yr-old male with Morquio A received lumbar epidural-general anesthesia for bilateral distal femoral osteotomies. Preoperative imaging had revealed a stable cervical spine and moderate thoracic spinal stenosis with a mild degree of spinal cord compression. Systolic blood pressure (BP) was maintained within 20% of the pre-anesthetic baseline value. The patient sustained a severe thoracic spinal cord infarction. The epidural anesthetic contributed to considerable delay in the recognition of the diagnosis of paraplegia.

CONCLUSION

This experience leads us to suggest that, in patients with Morquio A, it may be prudent to avoid the use of epidural anesthesia without very firm indication, to support BP at or near baseline levels in the presence of even moderate spinal stenosis, and to avoid flexion or extension of the spinal column in intraoperative positioning. If the spinal cord/column status is unknown or if the patient is known to have any degree of spinal stenosis, we suggest that the same rigorous BP support practices that are typically applied in other patients with severe spinal stenosis, especially stenosis with myelomalacia, should apply to patients with Morquio A and that spinal cord neurophysiological monitoring should be employed. In the event that cord imaging is not available, e.g., emergency procedures, it would be prudent to assume the presence of spinal stenosis.