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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

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.

Atypical Presentation of Acute Angle-Closure Glaucoma in Maroteaux-Lamy Mucopolysaccharidosis with Patent Prophylactic Laser Peripheral Iridotomy: A Case Report

INTRODUCTION

Maroteaux-Lamy syndrome (MLS) is a rare progressive condition characterized by inflammation and scarring of multiple organs. Ocular complications caused by anterior segment abnormalities commonly cause visual impairment in MLS. Angle-closure glaucoma is one such complication, but there are limited data on presentation, workup, and management of this condition.

CASE PRESENTATION

This case report describes an atypical presentation of acute angle-closure glaucoma in a patient with MLS despite a prior prophylactic laser peripheral iridotomy-which would typically prevent an acute angle-closure attack-that was patent and intact at the time of angle closure.

DISCUSSION

Because of severe congenital anterior segment crowding, high axial hyperopia, and constant accommodative demand in patients with MLS, we recommend performing two prophylactic laser peripheral iridotomies simultaneously in the same eye instead of one. The mechanism for this indication differs from that in patients at risk of acute angle-closure glaucoma because of lens zonulopathy alone. We hope that this case report may help prevent vision loss and optimize quality of life in patients with MLS who may be wheelchair-bound but are typically high functioning with normal intelligence.

Craniocervical decompression in patients with mucopolysaccharidosis VI: development of a scoring system to determine indication and outcome of surgery

OBJECTIVE

To analyse diagnostic value of somato-sensory evoked potentials (SEP), magnetic resonance imaging (MRI), and clinical neurological examination in the decision for decompression surgery in mucopolysaccharidosis (MPS) VI patients with craniocervical cord compression (CCJ).

METHODS

We retrospectively analysed neurological examination, SEP of the median nerve and MRI outcomes from 31 MPS VI patients. Individual scores for each test (based on severity of findings) and a sum of scores of all three procedures (CCJ score) were evaluated for their potential to measure the need for and improvement after surgery. Differences between rapidly and slowly progressive patients were also evaluated.

RESULTS

Fourteen patients (45 %) aged 4-34 years underwent decompression surgery. Median age at first operation was lower in rapidly than in slowly progressive patients (12 vs. 24 years; P = 0.008). Neurological and SEP findings but not MRI results differed significantly between non-operated and operated patients (P < 0.001, P = 0.003 and P = 0.08, respectively). A significant relationship was found between MRI and clinical neurological examination (P < 0.001) and between SEP and clinical neurological examination (P = 0.01) but not between MRI and SEP (P = 0.06). The CCJ score discriminated between operated and non-operated patients (4-9 points vs. 0-3 points; P < 0.001) and decreased in 61.5 % of patients after surgery.

CONCLUSIONS

CCJ is common in rapidly and slowly progressive MPS VI patients. The CCJ score is an objective and transparent tool for assessing pathology of the CCJ, the need for surgery, and improvement after surgery.

A multinational, multidisciplinary consensus for the diagnosis and management of spinal cord compression among patients with mucopolysaccharidosis VI

Cervical cord compression is a sequela of mucopolysaccharidosis VI, a rare lysosomal storage disorder, and has devastating consequences. An international panel of orthopedic surgeons, neurosurgeons, anesthesiologists, neuroradiologists, metabolic pediatricians, and geneticists pooled their clinical expertise to codify recommendations for diagnosing, monitoring, and managing cervical cord compression; for surgical intervention criteria; and for best airway management practices during imaging or anesthesia. The recommendations offer ideal best practices but also attempt to recognize the worldwide spectrum of resource availability. Functional assessments and clinical neurological examinations remain the cornerstone for identification of early signs of myelopathy, but magnetic resonance imaging is the gold standard for identification of cervical cord compression. Difficult airways of MPS VI patients complicate the anesthetic and, thus, the surgical management of cervical cord compression. All patients with MPS VI require expert airway management during any surgical procedure. Neurophysiological monitoring of the MPS VI patient during complex spine or head and neck surgery is considered standard practice but should also be considered for other procedures performed with the patient under general anesthesia, depending on the length and type of the procedure. Surgical interventions may include cervical decompression, stabilization, or both. Specific techniques vary widely among surgeons. The onset, presentation, and rate of progression of cervical cord compression vary among patients with MPS VI. The availability of medical resources, the expertise and experience of members of the treatment team, and the standard treatment practices vary among centers of expertise. Referral to specialized, experienced MPS treatment centers should be considered for high-risk patients and those requiring complex procedures. Therefore, the key to optimal patient care is to implement best practices through meaningful communication among treatment team members at each center and among MPS VI specialists worldwide.

Oral and systemic manifestations of mucopolysaccharidosis type VI: a report of seven cases

Mucopolysaccharidosis (MPS) is a group of rare metabolic diseases characterized by intralysosomal accumulation of glycosaminoglycans. MPS type VI or Maroteaux-Lamy syndrome is an autosomal-recessive syndrome caused by mutations in the lysosomal enzyme arylsulfatase B. A defect in the gene leads to accumulation of nondegraded mucopolysaccharides, resulting in severe cellular dysfunction with multisystem expression. The oral manifestations of MPS VI are not well described in the literature. This paper presents a series of seven patients with MPS VI, with the description of the general clinical manifestations and focus on the still rarely studied oral manifestations of the syndrome. Among them were high palate, open bite, impacted and/or included teeth, thickening of the pericoronal follicle, and changes in the temporomandibular joint.

Mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome) with a predominantly cardiac phenotype

We present here the first literature description of a predominantly cardiac phenotype in a patient homozygous for missense mutation p.R152W in the N-acetylogalactosamine-4-sulfatase (arylsulfatase B, ARSB) gene. An adult Caucasian woman, who displayed very few symptoms up to her late thirties, was diagnosed with mucopolysaccharidosis type VI (MPS VI) after her hospitalization due to acute heart failure originating mainly from valve disease. In addition to her cardiac phenotype some musculoskeletal involvement without other MPS characteristic features were found. Despite the common pharmacologic treatment and implementation of enzyme replacement therapy with galsulfase the patient died at the age of 38 years because of decompensation of chronic heart failure.

Spinal cord compression in young children with type VI mucopolysaccharidosis

Spinal cord compression (SCC) is a known complication of mucopolysaccharidosis type VI (MPS VI) secondary to atlantoaxial subluxation, craniovertebral stenosis, posterior longitudinal ligament hypertrophy, or dural thickening. SCC is expected to occur in the natural history of the disease, regardless of enzyme replacement therapy (ERT), as intravenous enzyme does not cross the blood-brain barrier. We describe six MPS VI children with SCC, all diagnosed before 7years of age. Within this group, four of the children were diagnosed with SCC after the introduction of ERT. We hypothesize that these patients may illustrate the previously undetected risk of increased joint mobility caused by ERT which may have contributed to increased cervical instability by loosening the neck joint, thus leading to or unmasking SCC. We reinforce the need for close follow-up of SCC, periodic neurological assessment, spine imaging, and neurophysiology in all MPS VI patients before and during ERT. Neurophysiological abnormalities may precede changes in MRI images (as shown in patients 4 and 5 from this sample) and should, therefore, be accessed in MPS VI patient evaluations, allowing for timely intervention and better prognosis. We recognize the limitations of these data due to the small sample size and recommend further investigation into this patient population.

Clinical outcomes following hematopoietic stem cell transplantation for the treatment of mucopolysaccharidosis VI

Mucopolysaccharidosis VI (MPS VI, Maroteaux-Lamy Syndrome) is one of approximately 50 known lysosomal storage disorders. MPS VI is characterized by an absence or deficiency of N-acetylgalactosamine 4-sulfatase (arylsulfatase B) resulting in accumulation of dermatan sulfate. Prior to the availability of enzyme replacement therapy (ERT), the clinical management of MPS VI was limited to supportive care and allogeneic hematopoietic stem cell transplantation (HSCT); however, due to the rarity of this disease, little is known about the long-term outcomes of HSCT for MPS VI. The following retrospective study was performed using aggregate data gathered by the Center for International Blood and Marrow Transplant Research (CIBMTR) between 1982 and 2007 to determine survival probability for patients with MPS VI following allogeneic HSCT. This analysis identified 45 MPS VI patients with a median age of 5 years (range, 1-22 years) at the time they received an allogeneic HSCT. Cumulative incidence (95% CI) of acute graft-vs.-host disease at 100 days was 36% (21-53%). Probability of survival was 78% (65-89%) at 100 days and 66% (52-79%) at 1 and 3 years. While these data are based upon small numbers of recipients, they represent the largest series to date and may help clinicians assess the relative risks and benefits of currently available therapies.

Maroteaux-Lamy syndrome: orofacial features after treatment by bone marrow transplant

PURPOSE

The objective of the present study was to emphasise the oral and dental findings of a male patient with the Maroteaux-Lamy syndrome who successfully underwent bone marrow transplantation (BMT) at the age of 22 months.

CASE REPORT

A 15-year-old boy was referred to the Dentistry Division of the Catholic University of Brasília, Brazil, for dental diagnosis. General characteristics of the Maroteaux-Lamy syndrome, such as a large head, a short neck, corneal opacity, an open mouth with macroglossia, enlargement of the skull and a long anteroposterior dimension, were observed. The patient had received the benefit of a BMT at an early stage. Therefore, characteristics were presented in a moderate form, except for the skeletal symptoms.

DISCUSSION

Maroteaux-Lamy syndrome, also known as mucopolysaccharidosis type VI, is a lysosomal storage disorder that is caused by a deficiency of arylsulphatase B, which leads to an accumulation of dermatan sulphate in tissues and its increased excretion in urine. The deposition of mucopolysaccharides leads to a progressive disorder involving multiple organs. It is a rare condition that is inherited as an autosomal recessive trait. The characteristic features of this disease include retardation in growth, a large head, a short neck, corneal opacity, typical facies and spinal abnormalities. The main dental findings of this syndrome include gingival hyperplasia, hypertrophy of the maxillary alveolar ridge, macroglossia, unerupted dentition, malocclusions and dentigerous cyst-like follicles. BMT is a therapeutic treatment that is given to permanently replace any disorder caused due to the deficiency of enzymes in patients with storage diseases.

Lentiviral-mediated correction of MPS VI cells and gene transfer to joint tissues

Joint disease in mucopolysaccharidosis type VI (MPS VI) remains difficult to treat despite the success of enzyme replacement therapy in treating other symptoms. In this study, the efficacy of a lentiviral vector to transduce joint tissues and express N-acetylgalactosamine-4-sulphatase (4S), the enzyme deficient in MPS VI, was evaluated in vitro and the expression of beta-galactosidase was used to evaluate transduction in vivo. High viral copy number was achieved in MPS VI fibroblasts and 4-sulphatase activity reached 12 times the normal level. Storage of accumulated glycosaminoglycan was reduced in a dose dependent manner in both MPS VI skin fibroblasts and chondrocytes. Enzyme expression was maintained in skin fibroblasts for up to 41 days. Comparison of two promoters; the murine phosphoglycerate kinase gene promoter (pgk) and the myeloproliferative sarcoma virus long terminal repeat promoter (mpsv), demonstrated a higher level of marker gene expression driven by the mpsv promoter in both chondrocytes and synoviocytes in vitro. When injected into the rat knee, the expression of beta-galactosidase from the mpsv promoter was widespread across the synovial membrane and the fascia covering the cruciate ligaments and meniscus. No transduction of chondrocytes or ligament cells was observed. Transduction was maintained for at least 8 weeks after injection. These results indicate that the lentiviral vector can be used to deliver 4S to a range of joint tissues in vitro and efficiently transduce synovial cells and express beta-galactosidase in vivo.

Left ventricular aneurysm in a patient with mucopolysaccharidosis type VI (Maroteaux–Lamy syndrome): clinical and pathological correlation

A 22-year-old man was diagnosed with mucopolysaccharidosis type VI, also known as Maroteaux-Lamy syndrome, which is a known cause of cardiac valvular disease. He presented with exercise intolerance and was diagnosed with a large, apical, left ventricular aneurysm (LV aneurysm) and subsequently underwent left ventricular aneurysmectomy with improvement in clinical status. Previous echocardiograms revealed that the LV aneurysm was new and is, therefore, likely acquired rather than congenital. Pathology confirmed a true aneurysm, replacement fibrosis, and PAS-positive material in cardiomyocytes. Subsequent echocardiography revealed progression of valvular heart disease with moderate stenosis of the aortic and mitral valves. We propose that altered metabolism of glycosaminoglycans in the extracellular matrix may have contributed to the development of the LV aneurysm in this patient.

The ocular features of the mucopolysaccharidoses

AIMS

The mucopolysaccharidoses (MPS) are a heterogeneous group of rare disorders characterised by accumulation of glycosaminoglycans within multiple organ systems. This study aimed to determine the prevalence and severity of ocular complications in patients with MPS.

METHODS

Clinical ophthalmic features and electrodiagnostic results of 50 patients with a diagnosis of MPS were retrospectively reviewed.

RESULTS

A total of 79% of MPS IH patients had a visual acuity of less than 6/12 equivalent in their better eye, compared to 44% of MPS IH/S and 25% of MPS VI patients. In total, 16% of MPS IH and 25% of MPS IH/S had severe corneal opacification, compared to 38% of MPS VI patients. 16% of MPS IH patients had optic atrophy; 21% of MPS VI patients had mild disc swelling, 29% had markedly swollen discs, and 14% had optic atrophy. One patient with MPS IH, one with MPS IH/S and six with MPS VI had ocular hypertension. One MPS VI patient had glaucoma that required topical therapy. Nine patients with MPS IH had electrodiagnostic evidence of retinopathy, as did one MPS VI patient.

CONCLUSIONS

Ocular complications causing significant reduction in vision are common in MPS. The majority of MPS I and MPS VI patients have corneal opacification, which can lead to difficulties in diagnosis and monitoring of glaucoma, optic disc changes, and retinopathy.

Pseudoglaucoma em mucopolissacaridose tipo VI: relato de caso

The authors report a case of a 19-year-old patient presenting with type VI mucopolysaccharidosis, diagnosed by genetic-clinical examination, demonstrating several systemic manifestations, including ocular disorders such as: corneal opacity, elevated intra-ocular pressure and increase of corneal thickness. The authors discuss the characteristic syndromic findings and the influence of corneal thickness associated with an increase in intraocular pressure leading to unnecessary antiglaucomatous treatment.

The oral manifestations of Maroteaux-Lamy syndrome (mucopolysaccharidosis VI): A case report

Maroteaux-Lamy syndrome is one of the genetic disorders involving disturbances in mucopolysaccharide metabolism resulting in increased storage of acid mucopolysaccharide in various tissues. The basic defect in Maroteaux-Lamy syndrome is a deficiency of arylsulfatase B, which leads to accumulation of dermatan sulfate in tissues and their urinary excretion. The deposition of mucopolysaccharides leads to a progressive disorder involving multiple organs that often results in death in the second decade of life. This disease, which has several oral and dental manifestations, is first diagnosed on the basis of clinical findings. A large head, short neck, corneal opacity, open mouth associated with an enlarged tongue, enlargement of skull, and a long antero-posterior dimension are the main characteristic features. Dental complications can be severe and include unerupted dentition, dentigerous cystlike follicles, malocclusions, condylar defects, and gingival hyperplasia. An 11-year-old boy with Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI) is described in this article, with special emphasis on the oral manifestations.

Intra-articular enzyme administration for joint disease in feline mucopolysaccharidosis VI: enzyme dose and interval

Degenerative joint changes have been reported in human mucopolysaccharidosis VI (MPS VI) and are a prominent feature of feline MPS VI. Joint disease has proven refractory to intravenous enzyme replacement therapy (ERT) in the MPS VI cat because enzyme is unable to reach cells in cartilage. In this study, enzyme was infused directly into the intraarticular space to determine whether joint tissues are able to respond to replacement enzyme. Clearance of glycosaminoglycans from chondrocytes was observed at a dose of 10 microg recombinant human N-acetylgalactosamine-4-sulfatase (rh4S), but greater clearance was observed with higher doses. The chondrocytes at the articular surface were cleared preferentially. Lysosomal vacuolation in cruciate ligament and synovial cells also decreased upon addition of rh4S. One month after injection of rh4S, a slight reaccumulation of storage was observed at the surface of the joint, but extensive reaccumulation was observed 2 mo after injection. These results indicate that by bypassing the synovium using intraarticular ERT, significant reduction in storage material in joint tissues can be achieved. Localized ERT in the joint space provides a mechanism for delivering enzyme directly to the articular cartilage and a potential therapy for joint pathology in MPS VI.

Multilevel myelopathy in Maroteaux-Lamy syndrome and review of the literature

An 18-year-old male with Maroteaux-Lamy syndrome was presented with spastic quadriparesis. Magnetic resonance imaging of whole spinal canal revealed stenosis at multiple levels of cervical, thoracic and lumbar regions. By the guidance of combined evaluations of neurological examination, neuroradiological and electrophysiological findings, the most responsible spinal segment was detected each time he developed myelopathy and he underwent craniocervical, cervical and thoracolumbar decompressions consecutively. Ligamentum flavum hypertrophy was found to be the principal pathology responsible for the cord compression and myelopathy for all levels. The etiology of myelopathy and priority of the level for which decompression should be done in diffuse spinal stenosis were discussed with the literature review of Maroteaux-Lamy syndrome.

Joint and bone disease in mucopolysaccharidoses VI and VII: identification of new therapeutic targets and biomarkers using animal models

The mucopolysaccharidoses (MPS) are inherited metabolic disorders resulting from the defective catabolism of glycosaminoglycans. In this report, we find that the stimulation of MPS connective tissue cells by the inflammatory cytokines causes enhanced secretion of several matrix-degrading metalloproteinases (MMPs). In addition, expression of tissue inhibitor of metalloproteinase-1 was elevated, consistent with the enhanced MMP activity. These findings were not restricted to one particular MPS disorder or species, and are consistent with previous observations in animal models with chemically induced arthritis. Bromodeoxyuridine incorporation studies also revealed that MPS chondrocytes proliferated up to 5-fold faster than normal chondrocytes, and released elevated levels of transforming growth factor-beta, presumably to counteract the marked chondrocyte apoptosis and matrix degradation associated with MMP expression. Despite this compensatory mechanism, studies of endochondral ossification revealed a reduction in chondro-differentiation in the growth plates. Thus, although MPS chondrocytes grew faster, most of the newly formed cells were immature and could not mineralize into bone. Our studies suggest that altered MMP expression, most likely stimulated by inflammatory cytokines and nitric oxide, is an important feature of the MPS disorders. These data also identify several proinflammatory cytokines, nitric oxide, and MMPs as novel therapeutic targets and/or biomarkers of MPS joint and bone disease. This information should aid in the evaluation of existing therapies for these disorders, such as enzyme replacement therapy and bone marrow transplantation, and may lead to the development of new therapeutic approaches.

Postobstructive pulmonary oedema during anaesthesia in children with mucopolysaccharidoses

We present case reports of five patients with severe forms of mucopolysaccharidoses who developed postobstructive pulmonary oedema during anaesthesia. The difficulties of anaesthesia in these patients and the particular predisposition that these patients exhibit for the development of postobstructive pulmonary oedema is discussed.

Does deficiency of arylsulfatase B have a role in cystic fibrosis?

Cystic fibrosis (CF) is associated with mutation and abnormal function of the cystic fibrosis transmembrane conductance regulator (CFTR) that affects cellular chloride transport. Clinically, CF of the lung is associated with excessive accumulation of secretions, including the sulfated glycosaminoglycans, chondroitin sulfate and dermatan sulfate (DS), both of which contain sulfated N-acetylgalactosamine residues. The sulfatase enzymes, which are a highly conserved group of enzymes with high specificity for designated sulfate groups, include arylsulfatase B, a lysosomal enzyme. Arylsulfatase B, also known as N-acetyl galactosamine 4-sulfatase, can degrade DS and chondroitin-4 sulfate. Previously reported data demonstrated diminished activity of arylsulfatase B in lymphoid cell lines of patients with CF compared to normal control subjects. Frequent infections with Pseudomonas, a sulfatase-producing organism, occur in patients with CF, whereas infections with Mycobacterium tuberculosis, which lacks sulfatase activity, are infrequent. Additional investigation to determine if diminished function of arylsulfatase B is a consistent finding in cells of patients with CF may be informative, and may help to correlate the molecular, biochemical, and clinical characteristics of CF.

Carpal tunnel syndrome in a 28-month-old child

We report a 28-month-old male child, known to have Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI), who presented with inconsistent right hand discomfort. Clinical suspicion of right carpal tunnel syndrome was confirmed by nerve conduction and electromyographic studies, and a decompressive procedure was done with uneventful recovery. Carpal tunnel syndrome in mucopolysaccharidosis patients should be suspected, diagnosed and treated early for better outcome.

Articular chondrocytes from animals with a dermatan sulfate storage disease undergo a high rate of apoptosis and release nitric oxide and inflammatory cytokines: a possible mechanism underlying degenerative joint disease in the mucopolysaccharidoses

Mucopolysaccharidosis (MPS) Type VI (Maroteaux-Lamy Disease) is the lysosomal storage disease characterized by deficient arylsulfatase B activity and the resultant accumulation of dermatan sulfate-containing glycosaminoglycans (GAGs). A major feature of this and other MPS disorders is abnormal cartilage and bone development leading to short stature, dysostosis multiplex, and degenerative joint disease. To investigate the underlying cause(s) of degenerative joint disease in the MPS disorders, articular cartilage and cultured articular chondrocytes were examined from rats and cats with MPS VI. An age-progressive increase in the number of apoptotic chondrocytes was identified in the MPS animals by terminal transferase nick-end translation (TUNEL) staining and by immunohistochemical staining with anti-poly (ADP-ribose) polymerase (PARP) antibodies. Articular chondrocytes grown from these animals also released more nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha) into the culture media than did control chondrocytes. Notably, dermatan sulfate, the GAG that accumulates in MPS VI cells, induced NO release from normal chondrocytes, suggesting that GAG accumulation was responsible, in part, for the enhanced cell death in the MPS cells. Coculture of normal chondrocytes with MPS VI cells reduced the amount of NO release, presumably because of the release of arylsulfatase B by the normal cells and reuptake by the mutant cells. As a result of the enhanced chondrocyte death, marked proteoglycan and collagen depletion was observed in the MPS articular cartilage matrix. These results demonstrate that MPS VI articular chondrocytes undergo cell death at a higher rate than normal cells, because of either increased levels of dermatan sulfate and/or the presence of inflammatory cytokines in the MPS joints. In turn, this leads to abnormal cartilage matrix homeostasis in the MPS individuals, which further exacerbates the joint deformities characteristic of these disorders.

Neurosurgical interventions in children with Maroteaux-Lamy syndrome. Case report and review of the literature

This paper reports the case of a 14-year-old child with Maroteaux-Lamy syndrome (mucopolysaccharidosis type 6) who was treated consecutively for compressive damage of the optic nerves, hydrocephalus communicans and progressive spastic tetraparesis within 2 years. The clinical course of the patient is presented and the pathophysiologic mechanisms of disease progression in patients with Maroteaux-Lamy syndrome are discussed and reviewed.

Altered corneal stromal matrix organization is associated with mucopolysaccharidosis I, III and VI

The presence of cloudy corneas is a prominent feature of mucopolysaccharidosis (MPS) types I and VI, but not MPS IIIA or IIIB. The cause of corneal cloudiness in MPS I and VI is speculative. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma. Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. The purpose of this study was to compare the structural organization of the stromal extracellular matrix of normal corneas with that of MPS corneas. The size and arrangement of collagen fibrils in cloudy corneas from patients with MPS I were examined. The alterations observed were an increased mean fibril diameter with a broader distribution in the MPS corneas. The MPS I corneas also had altered fibril spacing and more irregular packing compared with normal control corneas. The clear corneas of patients with MPS IIIA and IIIB also showed increases in mean fibril diameter and fibril spacing. However, there was less variation indicating more regularity than seen in MPS I. In addition, corneas from cat models of certain MPS were compared to the human corneas. Cats with MPS I and VI, as well as normal control cats, were examined. Structural alterations comparable to those seen in human MPS corneas were seen in MPS I and VI cats relative to normal clear corneas. The findings suggest that cloudy corneas in MPS I and VI are in part a consequence of structural alterations in the corneal stroma, including abnormal spacing, size, and arrangement of collagen fibrils.

Mild form of Maroteaux-Lamy syndrome: corneal histopathology and ultrastructure

PURPOSE

Maroteaux-Lamy syndrome is one of the mucopolysaccharidoses (MPSs) that is caused by the incomplete degradation and storage of dermatan sulfate.

METHODS

We describe a 49-year-old female patient with the mild form of the disease (MPS VI-B) who developed bilateral increasing corneal opacification and increased intraocular pressure after cervical-fusion surgery. After treatment of the increased intraocular pressure, she underwent a penetrating keratoplasty of her right eye.

RESULTS

The histopathologic and ultrastructural features of the corneal button were the accumulation of membrane-bound vacuoles containing fibrillogranular and lamellated material in keratocytes and endothelial cells and thinning of Descemet's membrane with excrescences.

CONCLUSION

Our review of the literature reveals only two prior histologic studies of corneas affected by MPS VI B.

Ocular abnormalities in the mucopolysaccharidoses after bone marrow transplantation. Longer follow-up

OBJECTIVE

The purpose of the study was to provide longer follow-up of ocular findings in patients with mucopolysaccharidoses (MPS) after bone marrow transplantation (BMT).

DESIGN

The study design was a retrospective 6-year cohort evaluation.

PARTICIPANTS

Twenty-three patients with MPS (19 with MPS type I-H, 3 with MPS type III, 1 with MPS type VI) were studied.

INTERVENTION

Bone marrow transplantation was performed.

MAIN OUTCOME MEASURES

The following outcome measures were considered: vision, slit-lamp biomicroscopic and funduscopic examinations, intraocular pressure, electroretinography (ERG), and retinoscopy.

RESULTS

Thirteen (81%) of 16 patients showed ERG improvement in the first year. However, all patients showed slowly progressive decline of the ERG over longer follow-up. Other ocular findings included optic atrophy (n = 7 patients), disc edema (n = 6 patients), strabismus (n = 6 patients), nystagmus (n = 6 patients), cataract (n = 3 eyes), keratoconjunctivitis sicca (n = 4 eyes), ocular hypertension (n = 2 eyes), and glaucoma (n = 2 eyes).

CONCLUSIONS

The MPS are rare and heterogeneous disorders characterized by progressive retinal degeneration and blindness. Ocular abnormalities can occur as a result of the disease or as a consequence of BMT. Successful BMT has been shown to improve systemic health, but this may not reflect continuing ocular status and retinal function. Despite early improvement in ERG function, longer follow-up suggests progressive retinal decline.

Allogeneic CD34 selected peripheral stem cell transplant for Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI): rapid haemopoietic and biochemical reconstitution

Severe Maroteaux-Lamy syndrome is usually fatal in teenage or early adult life. Until recently, allogeneic bone marrow transplantation was the only form of enzyme replacement. We report the first successful transplant using CD34 selected, mobilised allogeneic blood cells for an inborn error of metabolism. A busulphan, cyclophosphamide, melphalan and antithymocyte globulin conditioning regimen was used as myeloablative therapy. Allogeneic CD34 selected granulocyte colony-stimulating factor (G-CSF)-mobilised blood cells from a HLA-identical sibling were used for the transplant. Haemopoietic reconstitution occurred on day 10 post-transplant with normal N-acetylgalactosamine-4-sulphatase levels. Infectious and graft-versus-host disease (GVHD) complications were minimal. We suggest that CD34 selected, mobilised allogeneic blood cells are a safe form of enzyme replacement therapy in Maroteaux-Lamy syndrome and should be considered in other metabolic diseases where the benefits of haemopoietic transplantation are proven.

Maroteaux-Lamy syndrome associated with growth hormone deficiency

Growth retardation is a common feature of mucopolysaccharide storage disorders, mostly considered to be a consequence of skeletal changes, Maroteaux-Lamy disease is a subtype of mucopolysaccharidosis, demonstrating somatic changes and skeletal deformities. We present a case with Maroteaux-Lamy disease associated with growth hormone deficiency. Magnetic resonance imaging study revealed marked signal changes in white matter due to the storage in brain and empty sella appearance in sellar region. In the presence of empty sella syndrome, hypothalamic-pituitary dysfunction due to the storage material may have led to growth hormone deficiency in this patient. Therefore, we recommend patients with mucopolysaccharidosis, especially those who have growth retardation, to be evaluated by hormonal and radiological studies.

Mucopolysaccharidosis: MPS VI and associated delayed tooth eruption

Eight cases of mucopolysaccharidosis Type VI (Maroteaux-Lamy syndrome) are reviewed and two cases are presented in detail. Developmental dental anomalies including unerupted and impacted permanent teeth and associated hyperplastic tooth follicles are seen frequently in MPS patients. The surgical implications and management are discussed. All patients reviewed had significant cardiovalvular disease. It is essential for the primary medical provider to establish early basic dental care and evaluation for delayed eruption of primary and permanent dentition. This will probably minimize the possibility of infective endocarditis and allow for early treatment of impacted teeth.

Hydrocephalus and pseudotumour cerebri in the mucopolysaccharidoses

This paper reports two cases of cerebrospinal fluid circulation disorder in children with mucopolysaccharidosis. One patient developed pseudotumour cerebri and the other communicating hydrocephalus. It is suggested that both have a similar underlying abnormality of cerebrospinal fluid absorption with different modes of presentation.

Characterization of osteopenia in feline mucopolysaccharidosis VI and evaluation of bone marrow transplantation therapy

Studies on a feline model of MPS VI demonstrated a marked osteopenia in iliac crest bone samples from young adult animals with fewer, finer trabeculae. In the absence of significant differences in bone remodeling, this was considered due to defects in endochondral ossification and the formation of fewer trabeculae. Cell-level bone formation was normal despite the presence of vacuolated osteoblasts. Affected animals had vacuolated osteocytes in larger lacunae. Cats of the same age who had received a bone marrow transplant 12 months prior as young kittens, had significantly more trabecular bone with thicker trabeculae. The presence of smaller osteocyte lacunae in these animals as compared to their untreated MPS VI cats appeared to be a direct effect of bone marrow transplantation and a useful parameter to monitor its efficacy.

Hydrocephalus, lumbar canal stenosis and Maroteaux-Lamy syndrome (mucopolysaccharidosis type 6). Case report

A case of communicating hydrocephalus and lumbar canal stenosis in a child with mucopolysaccharidosis type 6 is reported. We review the literature and discuss the aetiology of communicating hydrocephalus in this condition.

Mitral stenosis in the Maroteaux-Lamy syndrome: a treatable cause of dyspnoea

The case is reported of a young woman with the Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI) who presented with rapidly progressive dyspnoea due to mitral stenosis. Mitral valve replacement was performed and the appearance of the valve was typical of mucopolysaccharide infiltration. Dyspnoea in patients with the Maroteaux-Lamy syndrome may be due primarily to cardiac valve involvement, and in this setting, valve surgery is safe and effective.

Acute infantile cardiomyopathy as a presenting feature of mucopolysaccharidosis VI

An infant with a diagnosis of acute infantile cardiomyopathy was subsequently shown to have mucopolysaccharidosis VI. The mucopolysaccharidoses should be included in the differential diagnosis of infantile cardiomyopathy.

Valvular heart disease in four patients with Maroteaux-Lamy syndrome

BACKGROUND

Maroteaux-Lamy syndrome is a lysosomal storage disease of mucopolysaccharide metabolism (MPS type VI) that may involve the mitral and aortic valves. Affected patients have other skeletal and oropharyngeal malformations that complicate anesthetic and surgical management.

METHODS AND RESULTS

The present report describes the clinical, echocardiographic, and pathological findings in four patients with Maroteaux-Lamy syndrome. Two of three siblings underwent successful double-valve replacement for aortic and mitral valve stenoses. The third sibling, whose aortic and mitral valves were thick and fibrotic, died from septicemia after hip surgery. A fourth, unrelated patient also had successful double-valve replacement.

CONCLUSIONS

Our experience emphasizes the potential difficulties in preoperative assessment and surgical treatment as well as the unique problems related to airway management in patients with this syndrome.

Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome) with hearing impairment and pupillary membrane remnants

A Japanese boy aged 13 months was referred to us because thickened ribs had been observed on a chest X-ray taken during a respiratory infection. mucopolysaccharidosis type VI (MPS VI) was diagnosed based on urinary glycosaminoglycan analysis and low activity of arylsulfatase B in peripheral leukocytes. He had mild pupillary membrane remnants, but no corneal opacities. The auditory brainstem response revealed moderate hearing impairment, which may have caused his subnormal DQ score of 85 at the age of 19 months. Although MPS VI is characterized by normal intellectual development with normal hearing in early infancy, it is important to examine for hearing loss, especially when an infant with this disease shows developmental delay.

Somatosensory and magnetic evoked potentials in a postoperative paraparetic patient: case report

Somatosensory evoked potential (SSEP) testing is increasingly being used to test for spinal cord injuries and to monitor spinal surgery to reduce the risk of paraplegia. It is a sensory test, but it is assumed that any process severe enough to affect the motor tracts will also affect the sensory tracts and, therefore, be identified. Increasingly, however, isolated motor-tract involvement has been reported. A new technique, magnetic coil stimulation of the cortex, directly monitors the motor tracts. We report a case where the SSEP was normal although the magnetic motor-evoked potential was abnormal, supporting the hypothesis that direct testing of motor tracts may be advantageous.

Myelopathy due to diffuse thickening of the cervical dura mater in Maroteaux-Lamy syndrome: report of a case

A rare case of diffuse thickening of the cervical dura mater leading to cord compression in Maroteaux-Lamy syndrome (mucopolysaccharidosis VI) is reported. Spinal computed tomographic scans after intrathecal metrizamide injection and magnetic resonance images are shown. This condition presents as cervical myelopathy. Early decompression can be beneficial for patients with this infrequent metabolic disorder.

Endocardial fibroelastosis in mucopolysaccharidosis type VI

This case report describes two siblings less than 1 year of age who presented severely ill with a dilated cardiomyopathy. Full blood examination in both cases revealed marked granularity of neutrophils suggestive of mucopolysaccharidosis type VI. There were no physical features of a mucopolysaccharidosis but biochemical evaluation confirmed mucopolysaccharidosis type VI in both children. Autopsy in one patient confirmed endocardial fibroelastosis and electron microscopy of fibroblasts in the myocardium showed distention with membrane-bound vacuoles, consistent with a mucopolysaccharidosis. These siblings developed endocardial fibroelastosis before other clinical manifestations of the mucopolysaccharidosis. Assessment for metabolic causes of a cardiomyopathy is important, as cardiac disease may be the initial manifestation of a metabolic disease.

Otosclerosis and mucopolysaccharidosis

By means of a literature review, clinical observations and temporal bone histopathology in the Hunter syndrome, we could show a reason for otosclerosis in childhood, a very rare observation. Therefore we do not believe that the presence of otosclerotic foci in temporal bones is mere coincidence in MPS II. It seems there is a causal connection between the generalized metabolic disorder and otosclerosis on the basis of enzyme deficiency.

Mental retardation in a patient with Maroteaux-Lamy

An 8-year-old boy with Hurler-like traits including severe mental retardation excreted in his urine a pathognomonic amount of dermatan sulfate. Less than 10% residual activity of arylsulfatase B was found in his leucocytes and fibroblasts. Hurler fibroblasts corrected an abnormally high 35SO4-incorporation into acid mucopolysaccharides (MPS) in cultured fibroblasts, whereas Maroteaux-Lamy fibroblasts did not. The patient thus has a rare combination of Maroteaux-Lamy and severe mental retardation.