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Morquio B disease is an attenuated phenotype within the spectrum of beta galactosidase (GLB1) deficiencies. It is characterised by dysostosis multiplex, ligament laxity, mildly coarse facies and heart valve defects due to keratan sulphate accumulation, predominantly in the cartilage. Morquio B patients have normal neurological development, setting them apart from those with the more severe GM1 gangliosidosis. Morquio B disease, with an incidence of 1:250.000 to 1:1.000.000 live births, is very rare. Here we report the clinical-biochemical data of nine patients. High amounts of keratan sulfate were detected using LC-MS/MS in the patients' urinary samples, while electrophoresis, the standard procedure of qualitative glycosaminoglycans analysis, failed to identify this metabolite in any of the patients' samples. We performed molecular analyses at gene, gene expression and protein expression levels, for both isoforms of the GLB1 gene, lysosomal GLB1, and the cell-surface expressed Elastin Binding Protein. We characterised three novel GLB1 mutations [c.75 + 2 T > G, c.575A > G (p.Tyr192Cys) and c.2030 T > G (p.Val677Gly)] identified in three heterozygous patients. We also set up a copy number variation assay by quantitative PCR to evaluate the presence of deletions/ insertions in the GLB1 gene. We propose a diagnostic plan, setting out the specific clinical- biochemical and molecular features of Morquio B, in order to avoid misdiagnoses and improve patients' management., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2021. Published by Elsevier Inc.)

Mucopolysaccharidosis type IVA, also known as Morquio (Morquio-Brailsford) syndrome results from accumulation of keratan sulfate (KS) and chondroitin-6-sulfate (C6S), whereas the primary cause is mutations in the gene encoding galactosamine (N-acetyl)-6-sulfatase (GALNS). Phenotypically it seems to be a well-defined condition, with two main clinical forms: mild (attenuated) and severe, which are determined based on a combination of symptoms, i.e., enzymatic activity of GALNS, age of onset, and symptom severity. Nevertheless, the natural history of MPSIVA in relation to specific anthropometric parameters (growth, head circumference, body proportions, and face phenotype) is not precisely characterized. The aim of our work was to analyze the aforementioned anthropometric parameters, including correlation to molecular data (causative GALNS mutations).

Background: Mucopolysaccharidosis-IVA (Morquio A disease) is a lysosomal disorder in which the abnormal accumulation of keratan sulfate and chondroitin-6-sulfate is consequent to mutations in the galactosamine-6-sulfatase (GALNS) gene. Since standard DNA sequencing analysis fails to detect about 16% of GALNS mutant alleles, gross DNA rearrangement screening and uniparental disomy evaluation are required to complete the molecular diagnosis. Despite this, the second pathogenic GALNS allele generally remains unidentified in ~ 5% of Morquio-A disease patients., Methods: In an attempt to bridge the residual gap between clinical and molecular diagnosis, we performed an mRNA-based evaluation of three Morquio-A disease patients in whom the second mutant GALNS allele had not been identified. We also performed sequence analysis of the entire GALNS gene in two patients., Results: Different aberrant GALNS mRNA transcripts were characterized in each patient. Analysis of these transcripts then allowed the identification, in one patient, of a disease-causing deep intronic GALNS mutation. The aberrant mRNA products identified in the other two individuals resulted in partial exon loss. Despite sequencing the entire GALNS gene region in these patients, the identity of a single underlying pathological lesion could not be unequivocally determined. We postulate that a combination of multiple variants, acting in cis, may synergise in terms of their impact on the splicing machinery., Conclusions: We have identified GALNS variants located within deep intronic regions that have the potential to impact splicing. These findings have prompted us to incorporate mRNA analysis into our diagnostic flow procedure for the molecular analysis of Morquio A disease.

Morquio A syndrome, or mucopolysaccharidosis (MPS IV A), is an inherited lysosomal storage disorder which belongs to the group of mucopolysaccharidoses (MPSs). It is caused by N-acetylgalactosamine-6-sulfatase (GALNS) activity deficiency, which results in impaired degradation of glycosaminoglycans (GAGs), including keratan sulfate (KS) and chondroitin-6-sulfate (CS). These compounds infiltrate and disrupt the architecture of the extracellular matrix, compromising the integrity of the connective tissue. Patients with Morquio A have also been noted for exhibiting abnormalities of the larynx and vocal tract. The aim of the study was to assess voice alterations using noninvasive acoustic and electroglottographic voice analysis. Electroglottographic signal and acoustic analyses revealed considerable changes in the voices of patients with Morquio A syndrome when compared to the voices of healthy controls. Affected patients tended toward tense voice, incomplete glottal closure, increased incidence of vocal fold nodules, dysphonia, and hoarse voice. Morquio A syndrome is characterized by connective tissue disease, which adversely affects voice quality. The use of objective voice analysis makes it possible to quantitatively monitor changes in the vocal apparatus over the course of disease progression, and also allows for assessment of the effects of the enzyme replacement therapy.

Patients with mucopolysaccharidoses (MPS) have a plethora of multisystemic manifestations depending on the particular type, and atypical presentations are not uncommon. MPS type IVA (Morquio A syndrome) has predominant musculoskeletal system involvement and corneal clouding with normal intelligence and can be misdiagnosed as primary skeletal disorders in clinical practice. The absence of corneal clouding with normal urinary glycosaminoglycans (GAGs) level in a proportion of patients with MPS IVA makes the correct diagnosis even more challenging for physicians. Healthcare providers across specialties should have a high degree of suspicion for MPS IVA in all patients with suspected spondylo-epiphyseal dysplasia as early diagnosis and early treatment significantly improve the clinical outcome and activity of daily living., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Purpose: Main symptom of mucopolysaccharidosis type IVa (MPS IVa) is progressive systemic skeletal dysplasia. This is routinely monitored by cerebral and spinal MRI. The vascular system is generally not in the primary focus of interest. In our population of MPS IVa patients we observed vessel shape alterations of the vertebrobasilar arteries, which has not been described before., Material and Methods: MRI-datasets of 26 patients with MPS IVa acquired between 2008 and 2015 were eligible for retrospective analysis of the vertebrobasilar arteries. The vessel length and angle of the basilar artery (BA) and both vertebral arteries (VA) were analyzed. A deflection angle between 90° and 130° in the vessel course was defined as tortuosity, less than 90° as kinking. The results were compared to a matched control group of 23 patients not suffering from MPS., Results: The deflection angle [°] of the VA and BA was significantly decreased in the majority (85%) of MPS IVa patients compared to the control group: BA 132±24 vs. 177±6, BA/VA transition 113±21 vs. 152±13, right VA 108±23 vs. 156±13, left VA 110± 22 vs. 157±14 (all p<0.005). Likewise, vessels of MPS IVa patients were significantly longer compared to the control group: BA 27±4 vs. 21±2, right VA 20±6 vs. 10±1, left VA 18±5 vs. 11±2 (all p<0.005)., Conclusion: MPS IVa is associated with significantly increased tortuosity of vertebrobasilar arteries. Therefore the vascular system of MPS IVa patients should be monitored on routinely basis, as vessel shape alterations had been associated with dissections, leading to a higher risk of cerebrovascular events., (Copyright © 2017. Published by Elsevier B.V.)

Background: This post hoc subanalysis examined outcomes in adult patients with Morquio A (mucopolysaccharidosis IVA) who received enzyme replacement therapy (ERT) with elosulfase alfa over a 120-weeks period. Patients ≥18 years of age evaluated in an open-label, long-term extension study of elosulfase alfa (modified per protocol [MPP], n = 32; intent-to-treat [ITT], n = 37; MOR-005; NCT01415427) were compared with the ≥18-year-old untreated population with 2-years follow-up from a Morquio A natural history study (n = 10; MorCAP; NCT00787995). The MOR-005 MPP population excluded patients who underwent orthopedic surgical procedures or were noncompliant with study protocol (defined as missing ≥20% of ERT infusions). No MorCAP patients underwent orthopedic surgical procedures during the relevant time period. Endurance was assessed by the 6-min walk test (6MWT) and 3-min stair climb test (3MSCT). Activities of daily living (ADLs) were assessed by the MPS Health Assessment Questionnaire (MPS HAQ)., Results: Least squares (LS) mean (SE) 6MWT distances increased by 34.9 (11.7) m (MPP) and 30.5 (10.8) m (ITT) by week 120; LS mean (SE) change in 3MSCT at week 120 was 6.7 (1.8) stairs/min (MPP) and 5.9 (1.7) stairs/min (ITT). MorCAP patients showed no improvement in 6MWT distance or 3MSCT over a similar period of time. Pulmonary function measures remained unchanged in both MOR-005 and MorCAP adults. All MPS HAQ domain scores improved in MOR-005 adults, whereas MorCAP adults had unchanged caregiver assistance and mobility outcomes and worsened self-care outcomes., Conclusions: Long-term ERT in adult patients with Morquio A was associated with increased endurance and improvement in performance of ADLs., Trial Registration: Trial Registration NCT01415427 . Name of registry: Long-Term Efficacy and Safety Extension Study of BMN 110 in Patients With Mucopolysaccharidosis IVA (Morquio A Syndrome). Registered 8 August 2011, retrospectively registered.

Morquio A syndrome is an ultra-rare, inherited lysosomal storage disorder associated with progressive, multi-systemic clinical impairments, causing gradual loss of functional capacity and endurance, impaired quality of life, and early mortality. Studies in Morquio A patients have used the 6-min walk test (6MWT) to assess functionality and endurance and to evaluate disease progression or efficacy of treatment. The objective of the present study was to review minimal clinically important differences (MCIDs) for the 6MWT reported for disease states that widely use the 6MWT to evaluate clinical benefit and to discuss the results in view of the challenges in estimating MCID for ultra-rare diseases, using the case of elosulfase alfa in Morquio A patients. A systematic literature search was performed using Embase and Medline to identify studies specifically estimating the MCID using either anchor-based or distribution-based methods. A total of 19 publications on 17 studies were identified; none of these included patients with Morquio A syndrome or the wider disease category of lysosomal storage disorders. Therefore, the MCIDs determined by studies in patients with respiratory, cardiovascular, or musculoskeletal disease were compared to changes in the 6MWT seen in Morquio A patients in the pivotal phase 3 clinical trial of elosulfase alfa enzyme replacement therapy. The literature review showed a mean MCID for the 6MWT of 7% change (range 3-15%) in studies using anchor-based methods and a 9% change (range 4-16%) using distribution-based methods. Results of the elosulfase alfa clinical trial and its extension showed a placebo-adjusted 14.9% improvement in the 6MWT from baseline at week 24, which was greater than the mean MCID based on the results of the systematic literature review. After 2 years, 6MWT distance increased by a mean of 20.7% from baseline in a modified per-protocol population, versus a reduction of 6.9% in comparable untreated patients from the MorCAP natural history study over the same period. Although further research is required to establish the MCID of the 6MWT in Morquio A patients, the presented data provide further evidence for the positive effect of elosulfase alfa in this patient population.

Background: Mucopolysaccharidosis (MPS) IVA is a rare lysosomal storage disorder with multiple skeletal and non-skeletal abnormalities requiring multiple surgical interventions. It is well known that patients with MPS IVA suffer from tachycardia, but cardiac and hemodynamic alterations have not been reported to date. We investigated the cardiovascular and hemodynamic alterations in patients with MPS IVA and developed a possible patho-mechanism for cardiovascular deterioration during anesthesia., Material and Methods: In this observational study, serial cardiac examinations were performed in 54 patients with MPS IVA who were followed at the Children's Hospital of the Mainz Medical University (Mainz, Germany) between 1991 and 2014 (follow-up 1-24 years; median 5.8 years). Results were compared with data from a large central European cohort of more than 2000 healthy infants and children., Results: None of the patients had arterial hypertension, but 4% had evidence of increased pulmonary artery pressure. Patients developed aortic root extension up to 6.9 standard deviations above normal. Left-sided valve leaflet thickening occurred in 26 patients (five with valve disease). Patients had lower left ventricular dimensions (z: -1.02±0.1), lower stroke volumes (z: -2.3±0.17), lower left ventricular mass (z: -1.5±0.21), but higher wall thickness (z: +0.8±0.16), and higher work index (z: +2.5±0.2) compared to healthy control subjects. Cardiac output was preserved by an increase in heart rate of 21%. Sixty % of patients showed impaired diastolic filling; heart rate (99.0±1.8 vs. 92.0±2.1 bpm), age (18.0±1.8 vs. 14.2±1 years), and cardiothoracic ratio (61.6±3.6% vs. 55±4.2%) of these patients were higher compared to those with normal filling., Conclusions: The results of this study suggest an age-progressive disproportion of the intra-thoracic organs of patients with MPS IVA, which is accompanied by aortic root extension and thickened left ventricles, with reduced stroke volumes, impaired diastolic filling patterns, and increased heart rates., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: J.B. Hennermann has received travel reimbursement from BioMarin Pharmaceutical Inc. All other authors have declared that no competing interests exist. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Long-term efficacy and safety of elosulfase alfa enzyme replacement therapy were evaluated in Morquio A patients over 96weeks (reaching 120weeks in total from pre-treatment baseline) in an open-label, multi-center, phase III extension study. During this extension of a 24-week placebo-controlled phase III study, all patients initially received 2.0mg/kg elosulfase alfa either weekly or every other week, prior to establishment of 2.0mg/kg/week as the recommended dose, at which point all patients received weekly treatment. Efficacy measures were compared to baseline of the initial 24-week study, enabling analyses of changes over 120weeks. In addition to performing analyses for the entire intent-to-treat (ITT) population (N=173), analyses were also performed for a modified per-protocol (MPP) population (N=124), which excluded patients who had orthopedic surgery during the extension study or were non-compliant with the study protocol (as determined by ≥20% missed infusions). Six-minute walk test (6MWT) was the primary efficacy measure; three-minute stair climb test (3MSCT) and normalized urine keratan sulfate (uKS) were secondary efficacy measures. Mean (SE) change from baseline to Week 120 in 6MWT distance was 32.0 (11.3)m and 39.9 (10.1)m for patients receiving elosulfase alfa at 2.0mg/kg/week throughout the study (N=56) and 15.1 (7.1)m and 31.7 (6.8)m in all patients combined, regardless of dosing regimen, for the ITT and MPP populations, respectively. Further analyses revealed that durability of 6MWT improvements was not impacted by baseline 6MWT distance, use of a walking aid, or age. Mean (SE) change at Week 120 in the 3MSCT was 5.5 (1.9) and 6.7 (2.0)stairs/min for patients receiving elosulfase alfa at 2.0mg/kg/week throughout the study and 4.3 (1.2) and 6.8 (1.3)stairs/min in all patients combined, regardless of dosing regimen, for the ITT and MPP populations, respectively Across all patients, mean (SE) change at Week 120 in normalized uKS was -59.4 (1.8)% and -62.3 (1.8)% in the ITT and MPP populations, respectively. In the absence of a placebo group, significance of the sustained improvements could not be evaluated directly. However, to provide context for interpretation of results, comparisons were performed with untreated patients from a Morquio A natural history study. In contrast to the results of the extension study, the untreated patients experienced constant uKS levels and a gradual decline in endurance test results over a similar period of time. Differences from the untreated natural history study patients were significant for 6MWT, 3MSCT, and uKS outcomes for the cohort of patients receiving optimal dosing throughout the study and for all cohorts pooled together, for both ITT and MPP populations (P<0.05). Safety findings were consistent with those of the initial 24-week study, with no new safety signals identified., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to describe the spectral domain optical coherence tomography (SD-OCT) characteristics of patients with retinal manifestations of mucopolysaccharidoses (MPSs) I, II, and IV A., Design: The research was a prospective, observational study., Methods: Fourteen consecutive patients with variants of MPS and 15 healthy subjects underwent ophthalmic assessments including fundus examinations and SD-OCT., Results: The fundus examinations revealed that four patients (two MPS I and two MPS II) had pigmented retinopathy in both eyes. In addition, one MPS II patient had cystoid macular edema and two MPS II patients had abnormal disc morphology. SD-OCT revealed thinning of the parafoveal photoreceptor inner segment/outer segment (IS/OS; two MPS I and one MPS II) and perifoveal photoreceptor IS/OS (two MPS I and five MPS II). All MPS I and II patients exhibited thickening of the central foveal external limiting membrane (ELM). Fundus and SD-OCT findings were normal in MPS IV A and healthy subjects. The foveal ELM was significantly thicker in MPS I and II patients than in healthy subjects (P =0 .000 and P =0 .000, respectively). The foveal IS/OS was significantly thinner in MPS I, II, and IV A patients than in healthy subjects (P = 0.000, P = 0.000, and P = 0.030, respectively). The foveal retinal pigment epithelium layer was also thinner in MPS II patients than in healthy subjects (P = 0.007) CONCLUSIONS: In MPS, accumulation of glycosaminoglycans in retinal tissue induced retinal degeneration and pigmentary retinopathy. SD-OCT was a useful tool for detecting retinal pathology, particularly changes in ELM and IS/OS.

Background: Previous studies have shown that elosulfase alfa has a favorable efficacy/safety profile in Morquio A patients aged ≥5 y. This study evaluated safety and impact on urine keratan sulfate (uKS) levels and growth velocity in younger patients., Methods: Fifteen Morquio A patients aged <5 y received elosulfase alfa 2.0 mg/kg/week for 52 wk during the primary treatment phase of a phase II, open-label, multinational study. Primary endpoint was safety and tolerability; secondary endpoints were change in uKS and growth velocity over 52 wk., Results: All 15 patients completed the primary treatment phase. Six of 743 infusions (0.8%) administered led to adverse events (AEs) requiring infusion interruption and medical intervention. Eleven patients (73.3%) had ≥1 study drug-related AE, mostly infusion-associated reactions. Mean z-score growth rate per year numerically improved from -0.6 at baseline to -0.4 at week 52. Comparison to untreated subjects of similar age in the Morquio A Clinical Assessment Program study showed a smaller decrease in height z-scores for treated than for untreated patients. Mean percent change from baseline in uKS was -30.2% at 2 wk and -43.5% at 52 wk., Conclusion: Early intervention with elosulfase alfa is well-tolerated and produces a decrease in uKS and a trend toward improvement in growth.

In clinical practice, respiratory function tests are difficult to perform in Morquio syndrome patients due to their characteristic skeletal dysplasia, small body size and lack of cooperation of young patients, where in some cases, conventional spirometry for pulmonary function is too challenging. To establish feasible clinical pulmonary endpoints and determine whether age impacts lung function in Morquio patients non-invasive pulmonary tests and conventional spirometry were evaluated. The non-invasive pulmonary tests: impulse oscillometry system, pneumotachography, and respiratory inductance plethysmography in conjunction with conventional spirometry were evaluated in twenty-two Morquio patients (18 Morquio A and 4 Morquio B) (7 males), ranging from 3 to 40 years of age. Twenty-two patients were compliant with non-invasive tests (100%) with the exception of IOS (81.8%-18 patients). Seventeen patients (77.3%) were compliant with spirometry testing. All subjects had normal vital signs at rest including >95% oxygen saturation, end tidal CO2 (38-44 mmHg), and age-appropriate heart rate (mean=98.3, standard deviation=19) (two patients were deviated). All patients preserved normal values in the impulse oscillometry system, pneumotachography, and respiratory inductance plethysmography, although predicted forced expiratory total (72.8±6.9 SE%) decreased with age and was below normal; phase angle (35.5±16.5°), %rib cage (41.6±12.7%), resonant frequency, and forced expiratory volume in 1 s/forced expiratory volume total (110.0±3.2 SE%) were normal and not significantly impacted by age. The proposed non-invasive pulmonary function tests are able to cover a greater number of patients (young patients and/or wheel-chair bound), thus providing a new diagnostic approach for the assessment of lung function in Morquio syndrome which in many cases may be difficult to evaluate. Morquio patients studied herein demonstrated no clinical or functional signs of restrictive and/or obstructive lung disease., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: To report and discuss the multi-domain impact of elosulfase alfa, with focus on tertiary and composite endpoints, in the 24-week, randomized, double-blind, placebo-controlled phase 3 trial in patients with Morquio A syndrome (mucopolysaccharidosis IVA)., Methods: Patients with Morquio A syndrome aged ≥5 years were randomized 1:1:1 to elosulfase alfa 2.0mg/kg/week (qw; N=58), elosulfase alfa 2.0mg/kg/every other week (qow; N=59), or placebo (N=59) for 24 weeks. Primary and secondary efficacy measures were 6-minute walk test (6MWT; primary), 3-minute stair climb test (3-MSCT) and urinary keratan sulfate (KS). Safety was also evaluated. Tertiary efficacy measures included respiratory function measures, activities of daily living (MPS Health Assessment Questionnaire [MPS-HAQ]), anthropometric, echocardiographic and radiographic measures, hearing and corneal clouding assessment. In order to fully characterize treatment impact in this heterogeneous disorder, the effect of elosulfase alfa on composite efficacy measures was evaluated as well., Results: The study was not designed to have sufficient power for any of the tertiary outcomes. For most tertiary endpoints, subjects treated with the weekly dose of elosulfase alfa improved more than those receiving placebo. The largest treatment effects were seen in maximal voluntary ventilation (MVV), MPS-HAQ, height, and growth rate. The qow group appeared similar to placebo. The analysis of a pre-specified composite endpoint (combining changes from baseline in 6MWT, 3MSCT and MVV z-scores equally weighted) showed a modest positive impact of elosulfase alfa qw versus placebo group (P=0.053). As a pre-specified supportive analysis, the O'Brien Rank Sum composite endpoint (changes from baseline in 6MWT, 3MSC, and MVV), analysis also showed that the qw group performed better than the placebo group (P=0.011). In post-hoc analyses, combinations of other endpoints were also explored using the O'Brien Rank Sum test and showed statistically significant differences between elosulfase alfa qw and placebo favoring elosulfase alfa qw. Differences between elosulfase alfa qow and placebo were not statistically significant. Positive changes were observed in most tertiary variables, demonstrating the efficacy of weekly treatment with elosulfase alfa., Conclusions: Treatment with weekly elosulfase alfa led to improvements across most efficacy measures, resulting in clinically meaningful benefits in a heterogeneous study population., (Copyright © 2014. Published by Elsevier Inc.)

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., (Copyright © 2014. Published by Elsevier Inc.)

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.

Elosulfase alfa (Vimizim™) is a recombinant form of N-acetylgalactosamine-6-sulfatase (GALNS) that was developed by BioMarin Pharmaceutical Inc. as an enzyme replacement therapy for patients with mucopolysaccharidosis type IVA (MPS IVA), also known as Morquio A syndrome. Patients with MPS IVA have a GALNS deficiency, which results in serious musculoskeletal, cardiorespiratory and other system disturbances. Elosulfase alfa was approved by the US FDA on 14 February 2014 for the treatment of MPS IVA. The European Medicines Agency Committee for Medicinal Products for Human Use (CHMP) has recently recommended that elosulfase alfa be approved for use in the EU in the same indication. Within the last year, the manufacturer has also filed applications for approval for the use of elosulfase alfa in MPS IVA in Brazil, Australia, Canada and Mexico. This article summarizes the milestones in the development of elosulfase alfa leading to its first global approval in MPS IVA.

Background: Morquio A syndrome (or mucopolysaccharidosis IVa) is an ultra-rare multi-organ disease, resulting in significantly impaired functional capacity, mobility and quality of life (QoL)., Methods: This patient-reported outcomes survey evaluated the global burden of Morquio A among adults (≥18 years, N = 27) and children (7-17 years, N = 36), including the impact on mobility, QoL, pain and fatigue. QoL was assessed using the general Health-Related Quality of Life (HRQoL) questionnaire (the EuroQol [EQ]-5D-5L). Pain and pain interference with daily activities were assessed using the Brief Pain Inventory Short Form (BPI-SF) in adults and the Adolescent Pediatric Pain Tool (APPT) in children. Fatigue was assessed by questioning the patients on the number of evenings in a week they felt extremely tired., Results: The clinical data showed a wide heterogeneity in clinical manifestations between patients, with the majority of patients showing differing levels of endurance, short stature, bone and joint abnormalities, abnormal gait and eye problems. Mobility was considerably impaired: 44.4% of children and 85.2% of adult patients were using a wheelchair. High wheelchair reliance significantly reduced QoL. This was mainly driven by reduced scores in the Mobility, Self-care, and Usual Activity domains. The HRQoL utility values were 0.846, 0.582 and 0.057 respectively in adults not using a wheelchair, using a wheelchair only when needed and always using a wheelchair; values were 0.534, 0.664 and -0.180 respectively in children. Employed adult patients had a better HRQoL than unemployed patients (HRQoL utility value 0.640 vs. 0.275, respectively).64% of children and 74% of adult patients had joint pain; fatigue was reported by 69% of children and 63% of adults. Overall, increased mobility was associated with more severe and widespread pain and more fatigue., Conclusions: The HRQoL of Morquio A patients is mainly driven by the ability to remain independently mobile without becoming wheelchair dependent. Their QoL reduces dramatically if they always have to use their wheelchair. Even a slightly better mobility (wheelchair use only when needed) greatly improves QoL. Maintenance of functional capacity and mobility paired with better pain management are likely to improve QoL.

Background: The mucopolysaccharidoses (MPS) comprise a group of inherited lysosomal storage disorders characterized by deficiencies in enzymes catalyzing the degradation of glycosaminoglycans. Impairment of pulmonary function is an important health problem for patients with MPS. However, there are few published reports on the prevalence and severity of pulmonary dysfunction in relation to age and treatment in this disorder., Methods: To evaluate pulmonary function in patients with MPS, we performed spirometry in 35 patients (22 males and 13 females; 1 with MPS I, 12 with MPS II, 16 with MPS IVA, and 6 with MPS VI; mean age, 14.6 ± 5.9 years; age range, 6.4 years to 33 years). Forced vital capacity (FVC), forced expired volume in 1 sec (FEV1), FEV1 to FVC ratio (FEV1/FVC), peak expiratory flow (PEF), and mean forced expiratory flow during the middle half of FVC (FEF25-75% ) were measured., Results: Mean FVC, FEV1 , PEF, and FEF25-75% were 74.2%, 73.9%, 64.7%, and 37.1% of the predicted values, respectively. By spirometric classification, 32 patients (91%) had small airway disease (FEF25-75%  < 65%), 17 (48%) had restrictive lung disease, and 3 (9%) had obstructive lung disease. Percent predicted FVC, FEV1 , and PEF, as well as FEV1 /FVC, were all negatively correlated with age (P < 0.01), such that pubertal and post-pubertal patients had significantly lower values than younger patients. Of eight attenuated MPS II and VI patients who underwent follow-up pulmonary function testing after receiving enzyme replacement therapy (ERT) for 1.5-7.4 years, six showed improvements in % predicted FVC and five improved in % predicted FEV1 ., Conclusion: Our additional characterization of the types and prevalence of pulmonary function abnormalities seen in MPS patients should be useful for clinical care., (© 2013 Wiley Periodicals, Inc.)

Objectives: The objectives of this study are to quantify endurance and respiratory function and better characterize spectrum of symptoms and biochemical abnormalities in mucopolysaccharidosis IVA subjects., Methods: MorCAP was a multicenter, multinational, cross sectional study amended to be longitudinal in 2011. Each study visit required collection of medical history, clinical assessments, and keratan sulfate (KS) levels., Results: Data from the first visit of 325 subjects (53% female) were available. Mean age was 14.5 years. Mean ± SD height z-scores were -5.6 ± 3.1 as determined by the CDC growth charts. Mean ± SD from the 6-minute-walk-test was 212.6 ± 152.2m, revealing limitations in functional endurance testing, and 30.0 ± 24.0 stairs/min for the 3-minute-stair-climb test. Respiratory function showed limitations comparable to MPS VI patients; mean ± SD was 1.2 ± 0.9l based on forced vital capacity and 34.8 ± 25.5l/min based on maximum voluntary ventilation. Mean urinary keratan sulfate (uKS) was elevated for all ages, and negatively correlated with age. Higher uKS correlated with greater clinical impairment based on height z-scores, endurance and respiratory function tests. The MPS Health Assessment Questionnaire reveals impairments in mobility and activities of daily living in comparison to an age-matched control population., Conclusions: MPS IVA is a multisystem disorder with a continuum of clinical presentation. All affected individuals experience significant functional limitations and reduced quality of life. Older patients have more severe exercise and respiratory capacity limitations, and more frequent cardiac pathology illustrating the progressive nature of disease., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Mucopolysaccharidosis type IVA (MPS IVA) or Morquio syndrome is a multisystem disorder caused by galactosamine-6-sulfatase deficiency. Skeletal manifestations, including short stature, skeletal dysplasia, cervical instability, and joint destruction, are known to be associated with this condition. Due to the severity of these skeletal manifestations, the non-skeletal manifestations are frequently overlooked despite their significant contribution to disease progression and impact on quality of life. This review provides detailed information regarding the non-skeletal manifestations and suggests long-term assessment guidelines. The visual, auditory, digestive, cardiovascular, and respiratory systems are addressed and overall quality of life as measured by endurance and other functional abilities is discussed. Impairments such as corneal clouding, astigmatism, glaucoma, hearing loss, hernias, hepatomegaly, dental abnormalities, cardiac valve thickening and regurgitation, obstructive sleep apnea, tracheomalacia, restrictive and obstructive respiratory compromise, and muscular weakness are discussed. Increased awareness of these non-skeletal features is needed to improve patient care.

Mucopolysaccharidosis type IVa (MPS IVa, Morquio syndrome OMIM #253000) is a lysosomal storage disease caused by deficiency in N-acetylgalactosamine-6-sulfatase (GALNS, EC 3.1.6.4; encoded by GALNS gene at 16q24.3). Unlike other MPS disorders involving excessive heparan and dermatan sulfate, Morquio syndrome has not been associated with neurological involvement nor with intellectual impairment as this disorder of keratan sulfate has been described as a purely visceral and skeletal disorder. Neurocognitive assessment was undertaken of MPS IVa patients with age appropriate intellectual tests as well as a Child Behaviour Checklist as part of clinical follow up. Available neuroimaging studies (MRI and MR spectroscopy) were reviewed. Whilst more than half of the overall IQ scores fell in the average range, scores for 3/8 children fell below average. A number of behavioural problems were highlighted, including anxiety/depression, attention and somatic complaints. Subtle neuroimaging abnormalities were demonstrated in over half of the children. These findings present a challenge to existing assumptions about the nature of Morquio A syndrome. A hypothesis regarding the potential role of calcium signalling is explored.

The gait in children with Morquio syndrome (MPS IV) has not been previously described. We reviewed the charts, gait analysis reports, and radiographs of nine children with no previous lower extremity surgery. Children with MPS IV had a slower walking speed, reduced cadence, and reduced stride length as compared with normal (P<0.05). There was increased knee flexion, genu valgus, and external tibial torsion during stance (P<0.05). Kinetics showed that knee varus moment was increased (P<0.05). There was a strong correlation between genu valgus measured on gait analysis and standing radiographs (r=0.89).

Background: The modalities and results of surgical intervention in the lower extremity in children with Morquio syndrome type A [mucopolysaccharidosis-IV (MPS-IVA)] have not been well described. The aims of this study are to define the lower extremity deformities, and describe the results of intervention in MPS-IVA patients., Methods: Retrospective chart and radiograph review of 23 MPS-IVA patients with a minimum follow-up of >2 years. Patients were divided into no intervention and surgical groups. Demographic data, surgical details, clinical results, and complications were recorded. Standard lower extremity radiographic measurements made on standing radiographs at initial presentation, preoperatively (in surgical group), and at the final follow-up were used to study the deformities and effects of hip, knee, and ankle surgery. Descriptive statistics were performed., Results: There were 11 boys and 12 girls. The average age at presentation was 6.8±3.4 years and at the last visit was 13.5±5 years with a mean follow-up of 6.7±3.7 years. Progressive hip subluxation, genu valgum, and ankle valgus were observed in all patients without intervention. Twenty patients had a total of 159 lower extremity surgical procedures (average, 8 procedures per patient). There were 61 hip, 78 knee, and 20 ankle procedures. Surgery resulted in improvement of the center edge angle, femoral head coverage, lateral distal femoral angle, medial proximal tibial angle, tibiofemoral angle, and lateral distal tibial angle. Mechanical axis of the lower extremities improved after intervention. Six patients (12 hips) had recurrence of hip subluxation after acetabular osteotomies and/or femoral varus derotation osteotomy, and 8 patients (16 knees) had postoperative genu valgum recurrence requiring subsequent intervention. There was no recurrent hip subluxation after shelf acetabuloplasty., Conclusions: Progressive hip subluxation, genu valgum, and ankle valgus were seen and often needed surgery. After shelf acetabuloplasty and varus derotation osteotomy, there was no recurrent hip subluxation. Recurrence after genu valgum correction was common., Level of Evidence: Level IV, therapeutic case series.

Background: Dyggve--Melchior--Clausen syndrome (DMC) is a chondrodysplasia that bears significant phenotypic resemblance to mucopolysaccharidosis type IV (Morquio disease). Autosomal recessive mutations in DYM are known to cause this disease through its role in Golgi organisation and intracellular traffic, but genetic heterogeneity is suspected., Methods: A family with DMC and normal intellectual development underwent clinical evaluation followed by autozygosity mapping and exome sequencing. Immunoblot and immunofluorescence analyses were performed to characterise the effect of the mutation., Results: This multiplex consanguineous family links to a novel locus on 4q31.1. Exome sequencing revealed a missense mutation in RAB33B, which encodes a Rab protein with an established role in retrograde Golgi traffic. The mutation qualitatively replaces the invariant lysine residue in the guanine nucleotide-binding domain of this small GTPase protein and leads to marked protein deficiency, making it the likely causative mutation of DMC in this family., Conclusion: This study identifies a new DMC gene and highlights the role of intracellular traffic in the pathogenesis of this disease.

Background: This study was conducted to identify potential biomarkers that could be used to evaluate disease progression and monitor responses to enzyme replacement therapy (ERT) in patients with mucopolysaccharidosis (MPS) IVA., Methods: Levels of 88 candidate biomarkers were compared in plasma samples from 50 healthy controls and 78 MPSIVA patients not receiving ERT to test for significant correlations to the presence of MPSIVA. MPSIVA samples were also tested for correlations between candidate biomarkers and age, endurance, or urinary keratin sulfate (KS) levels. Then, levels of the same 88 analytes were followed over 36 weeks in 20 MPSIVA patients receiving ERT to test for significant correlations related to ERT, age, or endurance., Results: Nineteen candidate biomarkers were significantly different between MPSIVA and unaffected individuals. Of these, five also changed significantly in response to ERT: alpha-1-antitrypsin, eotaxin, lipoprotein(a), matrix metalloprotein (MMP)-2, and serum amyloid P. Three of these were significantly lower in MPSIVA individuals versus unaffected controls and were increased during ERT: alpha-1-antitrypsin, lipoprotein(a), and serum amyloid P., Conclusions: Candidate biomarkers alpha-1-antitrypsin, lipoprotein(a), and serum amyloid P may be suitable markers, in addition to urinary KS, to follow the response to ERT in MPSIVA patients.

Chondrogenic dwarfism in Morquio disease (mucopolysaccharidosis IV) has been suggested to be strongly linked to the abnormal lysosomal storage of cartilaginous extracellular matrix waste products within chondrocytes and fibroblasts. The specific genetic defects of enzymes of the keratan sulfate and chondroitin-6-sulfate metabolism have been detected at the molecular level and importantly contributed to the current knowledge on the phenotype of this rare metabolic disorder. However, the pathogenesis of this epiphyseal centered progressive skeletal disease does not seem to be fully explained by the dysfunction of the chondrocyte cytoplasm that presents with vacuolar changes in adult patients. I propose that the accumulation of extracellular matrix degradation product-laden macrophages within epiphyseal cartilage canals during the early postnatal period causes dysregulation in the synchronized process of the neoformation and resorption of the maturing radial growing epiphyses. Similarly, the resorption of pannus tissue following the microtraumatisation of weight-bearing joints and epiphysis-type bones becomes impacted. If the hypothesis is valid, the early pathogenesis in Morquio disease could be because of the inadequate regression of cartilage canals and impaired resorption and restitution of pannus tissue., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Information regarding the clinical outcome of enzyme replacement therapy (ERT) with recombinant human N-acetylgalactosamine 4-sulfatase (rhASB) for mucopolysaccharidosis (MPS) VI in Asian patients is limited. We reviewed nine Taiwanese patients with MPS VI (four males and five females; age range 1.4-21.1 years) treated with weekly intravenous infusions of rhASB (1.0 mg/kg) for at least 2 years. We assessed the biochemical and clinical response every 3 months. After 2 years of treatment, seven patients experienced improvement over baseline in the 6-min walk by a mean of 69.3 m (27.3%), and seven also increased the 3-min stair climb by a mean of 47 steps (35.7%). Shoulder range of motion in all patients improved, and Joint Pain and Stiffness Questionnaire scores improved by 0.597 points (30.5%). Four patients had improved pulmonary function [forced expiratory volume in 1 s increased by 0.130 L (26.3%) and forced vital capacity by 0.148 L (27.6%)]. The respiratory disturbance index decreased in the four patients who underwent polysomnography. A mean overall 51% decrease in urinary glycosaminoglycan excretion indicated a satisfactory biochemical response. ERT was well tolerated by all patients. This treatment is thus beneficial and appears to be safe for treatment of MPS VI in Taiwanese patients.

Morquio syndrome is a hereditary mucopolysaccharide disorder presenting with an abnormality of the craniocervical junction from childhood. We describe an adult patient who presented with Morquio syndrome who had subglottic narrowing of the airway, restrictive pulmonary disease, and mild mitral regurgitation and trivial aortic regurgitation. The anesthetic management of this patient for atlantoaxial stabilization is presented.

Background: Children with skeletal dysplasia (SD) often have pulmonary disease, which can be life threatening. In clinical practice, chest wall and formal respiratory function tests are difficult to perform owing to the small size and cooperation. The objective of this study was to demonstrate distinct thoracopulmonary function patterns in children with SD., Methods: We conducted a retrospective study reviewing pulmonary function tests from 17 patients with the diagnosis of SD. Three subgroups were studied: Morquio syndrome (MS), metatropic-spondylocostal dysplasia (MSD), and unspecified skeletal dysplasias (SDU). Rib cage contribution to tidal volume excursions (%RC), phase angle (Phtheta), phase relation during total breath (PhRTB), respiratory resistance (Rrs(5-35) Hz), respiratory reactance (Xrs(5-35) Hz), resonant frequency, and their frequency-dependency were analyzed. Values were age-matched and height-matched to reference values of healthy subjects., Results: There was a decrease in %RC and an increase in PhRTB (P < 0.05) in the SD group. %RC differed between subgroups [MS: 46.4 +/- 1.8% SE, MSD: 18.4 +/- 2.6% SE, SDU: 27.5 +/- 5.2% SE (P < 0.05)]; Phtheta was within reference values only in MS, which exhibited a decrease in Xrs at 5 Hz (P < 0.05) and an increase in Rrs independent of the frequency. SDU showed a decrease in Xrs at 35 Hz (P < 0.05), no differences were found in Rrs. In MS, a correlation was found between RC and Rrs at all frequencies (r = -0.98, P < 0.01) and between Xrs(5-10) and Phtheta (r = -0.93, P < 0.05)., Conclusions: Thoracoabdominal dysfunction was associated with altered chest wall reactance at high frequencies in a subgroup of SD patients with abnormal lung reactance and central airway involvement in MS.

Introduction: Complex spinal deformity (CSD) problems in pediatric patients result from a wide variety of congenital, acquired, neoplastic, or traumatic abnormalities that result in a combination of spinal deformity and spinal cord impingement. While these problems are rare, decompression, correction, instrumentation, and fusion are quite hazardous. Intraoperative neurophysiological monitoring (IONM) seems particularly beneficial in these patients., Methodology: Somatosensory evoked potentials, transcranial electrical motor evoked potentials (MEPs), direct waves, and electromyography were used in a variety of CSD cases over a period when IONM was routine for most spinal cases. Examples of cases in which IONM provided important intraoperative information and significantly affected the course of the operation are illustrated., Results: IONM is a useful tool particularly in CSD cases in pediatric patients but requires special expertise and anesthetic considerations. Loss of MEP appears to have particularly important adverse prognostic information. Conversely, maintenance of IONM provides significant reassurance that the spinal cord function is being maintained. Preserved but persistently diminished MEPs usually predict a neurological injury that will significantly improve and possibly completely recover. Issues concerning training, certification, oversight, standardization of equipment, and technique are partially but incompletely resolved., Discussion: IONM is an extremely valuable tool for management of CSD pediatric patients. The utility of IONM is such and the detection of unexpected or unanticipated neurological injury frequent enough that a strong argument that it be used in every spinal surgery case can be made.

Children with Morquio A disease grow poorly and become physically handicapped because of systemic bone disease. The purpose of this study was to describe observed growth patterns and their relationship with the physical condition of patients with Morquio A. In a one-center study, questionnaire-based longitudinal and cross sectional data were used to develop growth curves, to assess physical activity and to determine the incidence of surgical procedures in 354 patients with Morquio A. Mean birth lengths of boys and girls were 52.6 and 52.1 cm, respectively. The mean final heights for males and females at 18 years and older were 122.4 +/- 21.5 and 113.1 +/- 22.6 cm, respectively. These results corresponded to -7.4 SD for males and -7.7 SD for females compared to the normal healthy controls. Mean birth weights for boys and girls were 3.59 +/- 0.58 and 3.5 +/- 0.7 kg, respectively. The mean body mass index for males and females at over 18 years of age was 24.7 +/- 6.1 and 25.6 +/- 5.4 kg/m(2), respectively. The growth pattern in Morquio A patients was characterized by impaired growth velocity after 1 year of age. This is the first report providing growth charts for patients with Morquio A, which can help with monitoring the disease and assessing the clinical efficacy of treatments., (2008 Wiley-Liss, Inc.)

Mucopolysaccharidosis IVA (MPS IVA; Morquio A disease) is a lysosomal storage disorder caused by deficiency of N-acetylgalactosamine-6-sulfate sulfatase. The natural history of this disease is incompletely understood. To study which variables influence the clinical outcome, we conducted a study in which MPS IVA patients were asked to fill out a questionnaire with inquiries regarding family history, diagnosis, signs and symptoms, height, weight, surgical history, physical activity, and general complaints. A total of 326 patients (172 male, 154 female) from 42 countries enrolled in the Morquio A Registry programme. The mean age of patients enrolled was 14.9 years for males and 19.1 years for females, with a wide range of 1-73 years. Sixty-four per cent of the patients were under 18 years. Initial symptoms were recognized between 1 and 3 years of age (mean age 2.1 years) and mean age at diagnosis for the patients was 4.7 years. A progressive skeletal dysplasia was commonly observed among the MPS IVA patients. Fifty per cent of patients underwent surgical operations to improve their quality of life. The most frequent surgical sites include neck (51%), ear (33%), leg (26%) and hip (25%). The birth length for affected males and females was 52.2 +/- 4.7 cm and 52.2 +/- 4.5 cm, respectively. The final adult height for affected males and females was 122.5 +/- 22.5 cm and 116.5 +/- 20.5 cm, respectively. The results of this study provide a reference for assessment of efficacy for studies of novel therapies.

We reported a case of MPS IV A presented with dyspnea on exertion and respiratory muscle weakness. The patient underwent inspiratory muscle training (IMT) using threshold loading for 18 weeks. After 6 weeks of initial IMT, aerobic exercise training consisting of walking was added to the treatment program. Inspiratory muscle strength increased 70%, and 6-minute walk test (6MWT) distance increased to 47 m. With the inclusion of aerobic exercise training, additional increases in inspiratory muscle strength (7%) and 6MWT distance (26.5 m) were obtained. Exertional dyspnea improved from severe to slight after 6 weeks of IMT, and to very slight after additional 12 weeks of combined aerobic training and IMT. Health-related quality of life improved especially in social function, emotional function, vitality, and physical role. In conclusion, inspiratory muscles can be trained with the improvement of muscle strength in a patient with Morquio's syndrome.

Mucopolysaccharidosis IVA (MPS IVA), a progressive lysosomal storage disease, causes skeletal dysplasia through excessive storage of keratan sulfate (KS). We developed an ELISA-sandwich assay that used a MAb specific to KS. Forty-five blood and 59 urine specimens from MPS IVA patients (ages 1-65 y) were analyzed to determine whether KS concentration is a suitable marker for early diagnosis and longitudinal assessment of disease severity. Blood specimens were obtained from patients categorized as phenotypically severe (n = 36) and milder (n = 9). Urine specimens were also analyzed from patients categorized as severe (n = 56) and milder (n = 12), respectively. Blood KS levels (101-1525 ng/mL) in MPS IVA patients were two to eight times higher than those in age-matched controls (15-323 ng/mL). It was found that blood KS level varied with age and clinical severity. Blood KS levels in both MPS IVA and controls peaked between 5 and 10 y of age (mean, 776 versus 234 ng/mL, respectively). Blood levels in severe MPS IVA were 1.5 times higher than in the milder form. In contrast to blood, urine KS levels in both MPS IVA and controls peaked between 1 and 5 y (15.3 versus 0.26 mg/g creatinine), and thereafter declined with age. Urine KS level also varied with age and clinical severity, and the severe MPS IVA phenotype was associated with 6.7 times greater urine KS excretion than the milder one. These findings indicate that the new assay for blood or urine KS may be suitable for early diagnosis and longitudinal assessment of disease severity in MPS IVA.

As previously shown for [(3)H-galactosyl]ceramide, the breakdown of [(3)H-galactosyl]sphingosine was reduced in prosaposin-deficient skin fibroblast homogenates. Galactosylsphingosine hydrolysis was also deficient in cell homogenates from Krabbe's disease (beta-galactocerebrosidase-deficient) patients, but not acid beta-galactosidase-deficient patients. Moreover, hydrolysis of galactosylsphingosine in the prosaposin-deficient cell homogenates could be partially restored by adding pure saposin A or C, thereby identifying these saposins as essential facilitators of galactosylsphingosine hydrolysis. By contrast, saposins B and D had little effect on galactosylsphingosine hydrolysis in the prosaposin-deficient cells. The reduced galactosylsphingosine turnover in prosaposin-deficiency suggests that there could be a pathogenetic cerebral accumulation of galactosylsphingosine in this disorder.

Ten low molecular compounds analogous to galactose were screened for inhibition of human beta-galactosidase activity. Among them, 1-deoxy-galactonojirimycin and N-(n-butyl)-deoxy-galactonojirimycin showed an inhibitory effect at high concentrations. However, they restored mutant enzyme activities expressed in enzyme-deficient knockout mouse fibroblasts and human beta-galactosidosis fibroblasts at lower intracellular concentrations. This effect was more remarkable on G(M1)-gangliosidosis mutations (R201C, I51T, R201H, R457Q) than Morquio B disease mutations (W273L, Y83H). These low molecular compounds pass though the blood-brain barrier in mice. We hope that this new therapeutic approach will become clinically applicable in the near future.

Patients with MPS IV have a clinical disorder quite different from other MPS conditions. The major treatment issue revolves around the prevention of cervical myelopathy, although the other aspects of this multisystem disease should not be forgotten. Management is inevitably multidisciplinary and the paediatrician should play a lead role in the coordination of services for affected patients. The timing of occipito-cervical fusion and the selection of patients for this procedure remain unclear. A prophylactic approach to surgery is suggested in this review, although it is by no means clear that all patients will invariably develop cervical myelopathy if left untreated. Parents of affected children need considerable support in dealing with the affected child and the children themselves need help to try to come to terms with their severe physical disabilities. The Society for Mucopolysaccharide Diseases (55 Hill Avenue, Amersham, Bucks HP6 5BX, UK) has offered many parents and affected individuals considerable help as well as raising significant sums for research. Finally, it is important to remember the genetic nature of the disease and the possibility of prenatal diagnosis in subsequent pregnancies.

Two siblings with characteristic clinical and radiologic features of Morquio's disease are presented. Detailed pulmonary function tests, including vital capacity, flow rates, lung volumes, airway resistance, and lung compliance, were performed. The ventilatory studies suggested a restricted pattern due to chest cage dysfunction. Hypoxemia was noted in one patient and was shown to be due to right-to-left shunting, probably related to the microatelectasis as a result of the restricted chest cage.

Eighteen patients had ocular changes associated with spondyloepiphyseal dysplasia congenita, a rare cause of congenital dwarfism with normal mental development. Seven patients had nonprogressive myopia of 5.00 or more diopters. Vitreoretinal degeneration was encountered in six patients with high myopia, and vitreous syneresis was present in all patients. Corrected visual acuity was 20/50 or better in all patients. Retinal detachment was not encountered, although reports in the nonophthalmic literature claim up to 50% retinal detachment rate and poor visual prognosis in these patients.

The hearing status of 18 patients with Morquio's syndrome (mucopolysaccharidosis IV) was evaluated. All three patients under age 8 years had a conductive hearing loss. Fourteen of 15 patients 8 years of age and older had a mixed or sensorineural hearing loss; one had normal hearing. Six patients wore hearing aids. By the end of the first decade of life, most persons with Morquio's syndrome may be expected to have either a mixed or sensorineural hearing loss. Amplification may be required.

Analysis of retrospective growth data from 72 patients with diastrophic dysplasia, 62 patients with spondyloepiphyseal dysplasia congenita and 61 patients with pseudoachondroplasia permitted the establishment of preliminary reference growth standards for height for each disorder. In addition, a comparison of mean height curves for these three disorders and achondroplasia revealed dissimilarities in growth patterns.

Treatment of hereditary syndromes is still hampered by a scarcity of information. Morquio's syndrome is a mucopolysaccharidosis associated with chronic middle ear disease and with mixed or sensorineural hearing loss, although some patients with this syndrome have had normal hearing. This case is presented to report the occurrence of hearing loss and to report electronystagmographic findings for the first time.

Previous reports of pulmonary function in patients with Morquio's disease have emphasized the restrictive nature of their ventilatory defect. We describe a patient in whom pulmonary disability was secondary to upper airway obstruction from collapse of the trachea during head flexion. The same phenomenon was demonstrated in one of two other patients with Morquio's disease, both of whom were asymptomatic. Positionally dependent airway obstruction may be an important cause of pulmonary disability in Morquio's disease.

A theoretical discussion on the correlation between residual enzyme activities in inherited enzyme deficiencies and the development of neurological disorders is presented, based on the kinetic analysis of a simple model. Several metabolic diseases with wide spectra of clinical presentation are discussed in relation to this model.

The authors present the results of study of the somatotropic function of the hypophysis in 18 healthy children and in 70 patients suffering from various forms of growth retardation. The blood serum level of the STH of the hypophysis was studied by the authors by standard sets for radioimmunological determination on fasting stomach and in dynamics during the standard glucose-tolerance test. The data of basal, maximal and mean STH levels were taken into consideration. Investigations revealed a reduction of the somatotropic function of the hypophysis in the patients with hypophysial, cerebral and somatotropic nanism. With the first tow forms of growth retardation the disturbances were associated with the organic affections of the hypophysis or of the hypothalamus, and in the somatogenic one- they were functional. Somatotropic function was retained in spondylo-epiphysial dysplasia and in the patients with thyrogenic nanism given displacement therapy. In the patients with the Shereshevsky-Turner syndrome the STH secretion remained unchanged, but the reaction of the hypothalamo-hypophysial system to the functional distrubances was disturbed. An increase of the mean STH level followed complex therapy.