Morquio B disease: From pathophysiology towards diagnosis.

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.

Mis-splicing of the GALNS gene resulting from deep intronic mutations as a cause of Morquio a disease.

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.

Long-term endurance and safety of elosulfase alfa enzyme replacement therapy in patients with Morquio A syndrome.

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.

Non-invasive pulmonary function test on Morquio patients.

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.

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

OBJECTIVES: Baseline data from the Morquio A Clinical Assessment Program (MorCAP) revealed that individuals with Morquio A syndrome show substantial impairment in multiple domains including endurance and respiratory function (Harmatz et al., Mol Genet Metab, 2013). Here, 1- and 2-year longitudinal endurance and respiratory function data are presented. METHODS: Endurance was assessed using the 6-minute walk test (6MWT) and the 3-minute stair climb test (3MSCT). Respiratory function was evaluated by measuring forced vital capacity (FVC) and maximum voluntary ventilation (MVV). Data were analyzed using repeated measures ANCOVA models. Annualized estimates of change were determined using model estimates and interpolation. RESULTS: 353, 184, and 78 subjects were assessed at Year 0 (baseline), Year 1, and Year 2, respectively. The overall annualized estimate of change (SE) in 6MWT distance was -4.86±3.25m; a larger decline of -6.84±5.38m was observed in the subset of subjects meeting the inclusion/exclusion criteria of the Phase 3 clinical trial of elosulfase alfa (≥5years of age with baseline 6MWT distance ≥30 and ≤325m). In contrast, little change (-0.14±0.60stairs/min) was observed in 3MSCT. Annualized changes (SE) in FVC and MVV were 2.44±0.68% and 1.01±2.38%, respectively. FVC and MVV increased in patients aged ≤14years, but decreased in older patients. CONCLUSIONS: The natural history of Morquio A syndrome is characterized by progressive impairment of endurance as measured by the 6MWT. Longitudinal trends in FVC and MVV showing increase in younger patients, but decrease in older patients, are likely to be influenced by growth. Changes in 6MWT may represent a sensitive measure of disease progression in ambulatory Morquio A patients.

Multi-domain impact of elosufase alfa in Morquio A syndrome in the pivotal phase III trial.

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.

Safety and clinical activity of elosulfase alfa in pediatric patients with Morquio A syndrome (mucopolysaccharidosis IVA) less than 5 y.

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.

Spectral domain optical coherence tomography imaging of mucopolysaccharidoses I, II, and VI A.

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.

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

PURPOSE: We describe an instance in which complete paraplegia was evident immediately postoperatively after apparently uneventful lumbar epidural-general anesthesia in a patient with Morquio Type A syndrome (Morquio A) with moderate thoracic spinal stenosis. CLINICAL FEATURES: A 16-yr-old male with Morquio A received lumbar epidural-general anesthesia for bilateral distal femoral osteotomies. Preoperative imaging had revealed a stable cervical spine and moderate thoracic spinal stenosis with a mild degree of spinal cord compression. Systolic blood pressure (BP) was maintained within 20% of the pre-anesthetic baseline value. The patient sustained a severe thoracic spinal cord infarction. The epidural anesthetic contributed to considerable delay in the recognition of the diagnosis of paraplegia. CONCLUSION: This experience leads us to suggest that, in patients with Morquio A, it may be prudent to avoid the use of epidural anesthesia without very firm indication, to support BP at or near baseline levels in the presence of even moderate spinal stenosis, and to avoid flexion or extension of the spinal column in intraoperative positioning. If the spinal cord/column status is unknown or if the patient is known to have any degree of spinal stenosis, we suggest that the same rigorous BP support practices that are typically applied in other patients with severe spinal stenosis, especially stenosis with myelomalacia, should apply to patients with Morquio A and that spinal cord neurophysiological monitoring should be employed. In the event that cord imaging is not available, e.g., emergency procedures, it would be prudent to assume the presence of spinal stenosis.

The Morquio A Clinical Assessment Program: baseline results illustrating progressive, multisystemic clinical impairments in Morquio A subjects.

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.

Clinical overview and treatment options for non-skeletal manifestations of mucopolysaccharidosis type IVA.

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.

Intellectual and neurological functioning in Morquio syndrome (MPS IVa).

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.

Mutation in RAB33B, which encodes a regulator of retrograde Golgi transport, defines a second Dyggve--Melchior--Clausen locus.

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.

The lower extremity in Morquio syndrome.

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.

Enzyme replacement therapy for mucopolysaccharidosis VI--experience in Taiwan.

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.

Intraoperative neurophysiological monitoring during complex spinal deformity cases in pediatric patients: methodology, utility, prognostication, and outcome.

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.

Anesthetic management for foramen magnum decompression in a patient with Morquio syndrome: a case report.

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.

Novel data on growth phenotype and causative genotypes in 29 patients with Morquio (Morquio-Brailsford) syndrome from Central-Eastern Europe.

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).

Growth charts for patients affected with Morquio A disease.

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.

Voice alterations in patients with Morquio A syndrome.

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.