Urinary Glycosaminoglycans Research Articles

Clinical significance of urinary glycosaminoglycan excretion in inflammatory bowel disease patients.

The research focused on the diagnostic usefulness of urinary glycosaminoglycans excretion as new markers related to the ECM remodeling in the intestine. Their possible suitability in the diagnosis, differential diagnosis and treatment monitoring in the course of the two most common forms of inflammatory bowel diseases (IBD), i.e. ulcerative colitis (UC) and Crohn's disease (CD) were assessed in this study. Urinary excretion of total sulfated glycosaminoglycans (TGAG) and fraction of chondroitin sulfates (CS) were analysed in 47 patiens with IBD, including 31 patients with UC and 16 patients with CD at baseline and after one year of therapy. Sulfated GAGs excreted in urine were quantitated using standardized dye-binding method. A several-fold increase in urinary excretion of total GAG and CS fraction in both UC and CD patients compared to healthy subjects indicates the potential usefulness of quantitative urinary GAG analysis in the diagnosis of IBD. No differences were found in the amount of GAG excreted in the urine in patients with UC and CD. Adalimumab resulted in a decrease in the activity of the inflammatory process and the activity of the disease expressed in the Mayo scale, which was accompanied by an increase in the amount of CS excreted in the urine of UC patients. Moreover, significant correlation was found between Mayo scale and urinary total GAG and CS excretion in UC patients. The quantitative assessment of total glycosaminoglycans and chondroitin sulfates fraction in urine may be a marker helpful in the early diagnosis of IBD.

Urine and serum glycosaminoglycan levels in the diagnosis of urological diseases and conditions: A narrative review of the literature.

Glycosaminoglycans (GAGs) are sulfated, negatively charged polysaccharides produced in almost every cell of the human body. As GAGs are extracellularly localized, the changes in body fluids such as blood and urine may reflect pathological changes in the urinary system as observed in other pathologies. In this review, we determined the potential of urinary and/or serum GAG levels as a marker for kidney and urothelial system diseases. We performed a search in the PubMed, MEDLINE, and ScienceDirect databases until September 30, 2019. A number of studies reported changes in the urinary and/or plasma GAG levels or composition in urological diseases and conditions, such as renal cell carcinoma, kidney stone, bladder carcinoma, and overactive bladder. GAGs were found to have a predictive biomarker potential that could be limited by generalizability concerns.

Usefulness of urinary glycosaminoglycans assay for a mucopolysaccharidosis-specific screening.

Mucopolysaccharidoses (MPS), a group of inherited metabolic disorders characterized by the accumulation of glycosaminoglycans, can be diagnosed early through newborn screening programs. Establishing newborn screening in Morocco is a challenging task for multiple economic and social reasons. Screening in a Moroccan population using 1,9-dimethylmethylene blue urinary glycosaminoglycan (GAG) assays may allow for an earlier diagnosis of MPS. We studied the feasibility of implementing screening in Moroccan children as an alternative to national newborn screening. We determined the reference ranges for GAGs in the Moroccan population, their stability during transport, the effectiveness of this test as a screening procedure for MPS in patients, and its use as a screening test for MPS in the Imssouane region, where the rate of consanguineous marriage is 38%. Using dimethylmethylene blue assays, urine samples of 47 MPS patients were analyzed, together with urine samples from healthy controls (n = 368, age ranging from 1month to 25years), and from Imssouane region children (n = 350, age ranging from 6months to 24month). Precision, linearity, recovery, limits, and stability were tested. Urinary GAGs reference values are age and ethnicity dependent. The validation parameters established displayed great precision and accuracy leading to recoveries according to internationally accepted values for bioanalytical methods. Urinary GAGs were stable for a maximum of 7weeks at 40 °C. Screening of Imssouane children resulted in the detection of a 6-month-old child, diagnosed with MPS I. Our results demonstrate the usefulness of quantifying glycosaminoglycans for early screening of MPS.

Enzyme replacement therapy for the treatment of Hunter disease: A systematic review with narrative synthesis and meta-analysis

BackgroundIn the last 10 years enzyme replacement therapy (ERT) has become an alternative for the treatment of patients with Hunter disease (HD). Nevertheless, the information regarding efficacy and safety is scarce and mainly based on the pivotal trials. This scarcity is especially evident for adults and severe forms of HD. MethodsA systematic review of publications in the electronic databases PUBMED, EMBASE and Cochrane Central was undertaken. Clinical trials and observational studies were included. The data about efficacy and security were retrieved and analysed with Review Manager version 5.3. Results677 records were found, 559 remaining after the removal of duplicates. By title and abstract review, 427 were excluded. Full reading of the rest was made (122 publications) and 42 were finally included. It was not possible to perform meta-analysis of all the endpoints due to high heterogeneity in the reporting and measuring of variables in each publication. Eight clinical trials were included, 6 with high risk of bias. The quality of the other studies was low in 12%, average in 68% and good in 21%. Main findings were: a reduction in the elimination of glycosaminoglycans (GAG) in urine in all the studies (26/26), decrease in liver and spleen size (18/18), increase of 52.59 m (95% CI, 36, 42–68.76, p < .001) in the 6-min walk test (TM6M), increase in forced vital capacity (FVC) of 9.59% (95% CI 4.77–14.51, p < .001), reduction of the left ventricular mass index of 3.57% (95% CI 1.2–5.93) and reduction in mortality (OR) of 0.44 (0.27–0.71). DiscussionThe data suggests a clear and consistent effect of ERT in HD reducing the accumulation of GAGs in the body, demonstrated by the reduction of its urinary excretion, as well as by the reduction of its deposits (spleen, liver and heart). Likewise, there is an improvement in physical and respiratory function. In addition, a reduction in mortality has been observed. Lack of studies, small size of the samples, and methodological deficiencies are the main limitations to establish definite conclusions. ConclusionsThe data suggests that ERT is effective and safe in the treatment of HD. There is a need to evaluate patient-centred outcomes and the impact on quality of life.

An evaluation of the efficacy of allogeneic hematopoietic stem cell transplantation in patients with mucopolysaccharidosis type I (Hurler syndrome): the experience of the R.M. Gorbacheva Research Institute for Pediatric Oncology, Hematology and Transplantation

Mucopolysaccharidosis type I (MPS IH; Hurler syndrome) is a hereditary storage disease caused by a deficiency of the lysosomal enzyme alpha-L-iduronidase. Enzyme replacement therapy may extend the lifespan of affected patients by 6–12 years but the only currently available radical treatment option is allogeneic hematopoietic stem cell transplantation (allo-HSCT). Objectives: We aim to evaluate the influence of conditioning regimens of various intensities and “graft versus host” disease (GvHD) prophylaxis with anti-thymocyte globulin and post-transplant Cyclophosphamide (PTCy) on overall (OS) and event-free (EFS) survival, the incidence of GvHD, the normalization of alpha-L-iduronidase and glycosaminoglycan (GAG) levels over time as well as cardiovascular and cognitive recovery following allo-HSCT. The study was approved by the Independent Ethics Committee and the Scientific Council of the I.P. Pavlov First Saint Petersburg State Medical University. We included 28 patients with MPS IH who had received allo-HSCT at the clinic at the R.М. Gorbacheva Memorial Institute of Children Oncology, Haematology and Transplantation. The five-year OS was 89%, the EFS – 57%. The use of myeloablative conditioning regimens and allo-HSCT within 12 months of diagnosis improve EFS in affected patients. The cumulative incidence of grade II–IV acute GvHD and grade III–IV acute GvHD was 43% and 18% respectively. The use of PTCy results in a significantly lower incidence of this complication (69% vs 33%, p = 0.013). After allo-HSCT, normal alpha-L-iduronidase levels and urinary GAG excretion were achieved in cases where graft function was normal. Allo-HSCT is an effective treatment for patients with MPS IH. Myeloablative conditioning regimens are the preferred treatment modality for this group of patients but in cases of comorbidities or poor physical status at the time of allo-HSCT, conditioning regimens with reduced intensity may be opted for instead. PTCy may be used for GVHD prevention in patients with MPS IH without increasing the risk of cardiac toxicity.

Chondroitin sulfate disaccharide is a specific and sensitive biomarker for mucopolysaccharidosis type IVA.

Mucopolysaccharidosis type IVA (MPS IVA) is an inborn error of glycosaminoglycan (GAG) catabolism characterized by a deficiency of the lysosomal enzyme, N‐acetylgalactosamine 6‐sulphatase (GALNS). Consequently, partially degraded GAG, chondroitin 6‐sulfate (CS) and keratan sulfate (KS), accumulate in the lysosomes of affected cells, primarily in cartilage resulting in skeletal disease. Excessive urinary excretion of these GAG is often used as the initial biochemical parameter to inform a laboratory diagnosis. Here we present the utility of a CS‐disaccharide with a non‐reducing 6‐sulfated N‐acetylgalactosamine residue (HNAc‐UA (1S))—the enzyme's substrate—for the diagnosis and biochemical monitoring of MPS IVA patients. Following implementation of this method into the diagnostic laboratory, we identified one MPS IVA patient over 3 years of MPS urine screening, with no false positive results from 2050 urines tested. Uniquely, urinary concentrations of HNAc‐UA (1S) are independent of age meaning that age‐related reference ranges are not required. Urinary HNAc‐UA (1S) was also able to identify two MPS IVA siblings who remained misdiagnosed with spondyloepiphyseal dysplasia for 5 years because of normal urinary GAG. HNAc‐UA (1S) could also be used as a biomarker for monitoring response to enzyme replacement therapy (ERT) as there was a drop in urinary concentration following the administration of ERT in all 12 patients and concentrations correlated with urinary KS (R 2 = 0.92). In conclusion, HNAc‐UA (1S) is a reliable, sensitive and specific biomarker for the diagnosis of MPS IVA and can be used to biochemically monitor the response to ERT.

Retrospective chart review of urinary glycosaminoglycan excretion and long-term clinical outcomes of enzyme replacement therapy in patients with mucopolysaccharidoses

BackgroundMucopolysaccharidoses (MPS) are a group of rare, inherited metabolic diseases that result from a deficiency in one of several lysosomal enzymes essential for stepwise glycosaminoglycan (GAG) degradation, leading to GAG accumulation and widespread cellular pathology and clinical disease. Although disease presentation is heterogeneous, the clinical hallmarks are largely comparable across several MPS subtypes. Extensive data have shown that the level of urinary GAG (uGAG) excretion above normal is strongly correlated with disease severity and clinical outcomes in MPS diseases. Thus, change in uGAG excretion may have significant value as a potential primary endpoint in clinical trials of MPS diseases that are too rare to study using traditional clinical endpoints. MethodsA retrospective medical chart review was undertaken of patients with MPS I, II, and VI who had been treated long term with enzyme replacement therapy (ERT). The relationship between uGAG reduction and clinical outcomes relevant to the major clinical manifestations of these MPS diseases was evaluated. A multi-domain responder index (MDRI) score was calculated, measuring the following 4 domains: 6-min walk test, pulmonary function, growth rate, and Clinician Global Impression of Change. For each domain, a minimal important difference (MID) was defined based on published information of these outcome measures in MPS and other diseases. ResultsOf the 50 patients evaluated, 18 (36%) had MPS I, 23 (46%) had MPS II, and 9 (18%) had MPS VI. Forty-two were clinical practice patients and 8 had participated in clinical trials. Across all MPS subtypes, the mean (± SD) uGAG level at baseline was 66.0 ± 51.5 mg/mmol creatinine (n = 48) and there was a mean reduction of 54.6% following ERT. Analysis of the MDRI score based on the MID defined for each domain showed a greater magnitude of improvement in patients with increased uGAG reduction when compared with those patients with lower uGAG reduction for all assessed uGAG thresholds, and a trend toward a higher likelihood of positive mean MDRI score in patients with a uGAG reduction ≥40%. ConclusionsIn this retrospective study, uGAG reduction was associated with long-term clinical outcomes as assessed by a number of approaches, supporting the use of uGAG reduction as a biomarker primary endpoint.

The mutational spectrum of hunter syndrome reveals correlation between biochemical and clinical profiles in Tunisian patients

BackgroundMucopolysaccharidosis type II (MPS II) or Hunter syndrome is an X-linked recessive lysosomal storage disorder resulting from deficient activity of iduronate 2-sulfatase (IDS) and the progressive lysosomal accumulation of sulfated glycosaminoglycans (GAGs).MethodsA diagnosis of MPS II or Hunter syndrome was performed based on the following approach after a clinical and paraclinical suspicion. Two biochemical and molecular tests were carried out separately and according to the availability of the biological material.ResultsAll patients in this cohort presented the most common MPS II clinical features. Electrophoresis of GAGs on a cellulose acetate plate in the presence of a high concentration of heparane sulfate showed an abnormal dermatan sulfate band in the patients compared with that in a control case. Furthermore, leukocyte IDS activity ranged from 0.00 to 0.75 nmol/h/mg of leukocyte protein in patients.Five previously reported mutations were identified in this study patients: one splice site mutation, c.240 + 1G > A; two missense mutations, p.R88P and p.G94D; a large deletion of exon 1 to exon 7; and one nonsense mutation, p.Q396*. In addition, two novel alterations were identified in the MPS II patients: one frame shift mutation, p.D450Nfs*95 and one nonsense mutation, p.Q204*.Additionally, five known IDS polymorphisms were identified in the patients: c.419–16 delT, c.641C > T (p.T214M), c.438 C > T (p.T146T), c.709-87G > A, and c.1006 + 38 T > C.ConclusionsThe high level of urine GAGs and the deficiency of iduronate 2-sulfatase activity was associated with the phenotype expression of Hunter syndrome. Molecular testing was useful for the patients’ phenotypic classification and the detection of carriers.

Intravenous delivery for treatment of mucopolysaccharidosis type I: A comparison of AAV serotypes 9 and rh10

Mucopolysaccharidosis type I (MPS I) is an inherited metabolic disorder caused by deficiency of alpha-L-iduronidase (IDUA), resulting in accumulation of heparan and dermatan sulfate glycosaminoglycans (GAGs). Individuals with the most severe form of the disease (Hurler syndrome) suffer from neurodegeneration, intellectual disability, and death by age 10. Current treatments for this disease include allogeneic hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT). However, these treatments do not address CNS manifestations of the disease. In this study we compared the ability of intravenously administered AAV serotypes 9 and rh10 (AAV9 and AAVrh10) for delivery and expression of the IDUA gene in the CNS. Adult C57BL/6 MPS I mice were infused intravenously with either AAV9 or AAVrh10 vector encoding the human IDUA gene. Treated animals demonstrated supraphysiological levels and widespread restoration of IDUA enzyme activity in the plasma and all organs including the CNS. High levels of IDUA enzyme activity were observed in the plasma, brain and spinal cord ranging from 10 to 100-fold higher than heterozygote controls, while levels in peripheral organs were also high, ranging from 1000 to 10,000-fold higher than control animals. In general, levels of IDUA expression were slightly higher in peripheral organs for AAVrh10 administered animals although these differences were not significant except for the lung. Levels of IDUA expression between AAV 9 and rh10 were roughly equivalent in the brain. Urinary and tissue GAGs were significantly reduced starting at 3 weeks after vector infusion, with restoration of normal GAG levels by the end of the study in animals treated with either AAV9 or rh10. These results demonstrate that non-invasive intravenous AAV9 or AAVrh10-mediated IDUA gene therapy is a potentially effective treatment for both systemic and CNS manifestations of MPS I, with implications for the treatment of other metabolic and neurological diseases as well.

Intravenous Enzyme Replacement Therapy in Mucopolysaccharidoses: Clinical Effectiveness and Limitations.

The aim of this review is to summarize the evidence on efficacy, effectiveness and safety of intravenous enzyme replacement therapy (ERT) available for mucopolysaccharidoses (MPSs) I, II, IVA, VI and VII, gained in phase III clinical trials and in observational post-approval studies. Post-marketing data are sometimes conflicting or controversial, possibly depending on disease severity, differently involved organs, age at starting treatment, and development of anti-drug antibodies (ADAs). There is general agreement that ERT is effective in reducing urinary glycosaminoglycans and liver and spleen volume, while heart and joints outcomes are variable in different studies. Effectiveness on cardiac valves, trachea and bronchi, hearing and eyes is definitely poor, probably due to limited penetration in the specific tissues. ERT does not cross the blood–brain barrier, with the consequence that the central nervous system is not cured by intravenously injected ERT. All patients develop ADAs but their role in ERT tolerance and effectiveness has not been well defined yet. Lack of reliable biomarkers contributes to the uncertainties about effectiveness. The data obtained from affected siblings strongly indicates the need of neonatal screening for treatable MPSs. Currently, other treatments are under evaluation and will surely help improve the prognosis of MPS patients.

Erythrocytic membrane anionic charge, sialic acid content, and their correlations with urinary glycosaminoglycans in preeclampsia and eclampsia

Compared to healthy pregnant women, changes in erythrocytic membrane anionic charge (EAC) and urinary glycosaminoglycans (UGAGS) have been reported in African women with preeclampsia. A single previous study showed a decrease in erythrocytic membrane sialic acid (EMSA) in preeclampsia compared to healthy pregnancy; however, EMSA was not significantly different between women with preeclampsia and non-pregnant women. No study has focused on the relationships between EAC, EMSA, and UGAGS in preeclampsia and eclampsia compared to healthy pregnant and non-pregnant women of reproductive age. Moreover, the erythrocyte membrane contains sialoglycoproteins and proteoglycans involved in creating the negatively charged cell surface, disruption of which leads to erythrocyte aggregation seen in preeclampsia/eclampsia. However, the etiopathogenesis of preeclampsia and eclampsia remains unclear. Therefore, we evaluated the relationship between EAC, UGAGS, and EMSA in preeclampsia and eclampsia. Three groups of 30 women each were enrolled: Group A (non-pregnant women), Group B (healthy pregnant women without complications), and Group C (women with preeclampsia/eclampsia). EMSA was diminished under oxidative stress prevalent in eclampsia and preeclampsia which might have caused a decreased EAC. EAC was negatively correlated with UGAGS and positively correlated with EMSA (p < .001). EMSA was negatively correlated with UGAGS (p < .001). In conclusion, a loss of sialic acid from the erythrocyte membrane causes a significant decrease in the EAC which mirrors the decrease in the negative charge of the renal glomerular basement membrane and might lead to proteinuria and increased UGAGS excretion in preeclampsia and eclampsia.

Evidence of Degradation of Endothelial Glycocalyx in African Children with Falciparum Malaria

The microvasculature and endothelium play a pivotal role in pathophysiology of malaria. The endothelial glycocalyx (eGC) is a layer on the luminal side of vascular endothelial cells with involvement in homeostatic functions including regulation of vascular permeability, cellular adhesion and blood flow‐mediated nitric oxide formation. Breakdown products of eGC degradation include glycosaminoglycans (GAG) and syndecan‐1, a core protein. The objective of this study was to evaluate a possible role of eGC breakdown in the pathogenesis of malaria. We prospectively evaluated measures of endothelial glycocalyx integrity in children with severe and moderately severe malaria and healthy controls, and determined the relationship between glycocalyx integrity and markers of malaria severity, microvascular reactivity, and endothelial activation. At the Hubert Kairuki Medical Center in Dar es Salaam, Tanzania we studied 146 subjects, aged 2–11 years, including 60 healthy controls (HC), 49 patients with moderately severe malaria (MSM) and 37 patients meeting WHO criteria for severe malaria (SM). Ethics committee approvals were obtained prior to study initiation. We assessed eGC integrity biochemically by measuring plasma syndecan‐1 (ELISA) and total urinary glycosaminoglycan (GAG) breakdown products (dimethylmethylene blue assay). Angiopoietin‐2 has been reported to cause breakdown of eGC and was measured by ELISA. Quantitative measures of eGC were assessed using non‐invasive, side‐stream dark field (SDF) microscopy of the pinna and axilla. Levels of urinary GAG were increased in malaria patients compared with HC (mean±SEM 4.3±0.4 g/mol creatinine); MSM (12.4±1.0); SM (13.4±1.0); p&lt;0.0001. Plasma levels of angiopoietin‐2 and syndecan‐1 were also elevated in MSM and SM compared with HC (p&lt;0.0001), and significantly correlated with each other. For HC compared with MSM, imaging results showed eGC degradation [an increase in the perfused boundary region (mean±SEM 1.55±0.04 microns vs.1.68±0.05; p&lt;0.05)], increased microvascular density (549± 34 μm/mm2 vs. 649 ±38; p&lt;0.05)], and a decrease in the extent of RBC filling (79.1± 0.98% vs. 74.9±1.02%; p&lt;0.01). In conclusion, these results provide evidence for degradation of the eGC that could contribute to pathogenesis of vascular dysfunction in malaria. Decreased nitric oxide formation, endothelial activation and increased adhesion of infected RBC are potential consequences of the eGC degradation and vascular dysfunction. Administration of an agent that prevents or repairs eGC degradation may be helpful as adjunctive therapy for malaria.Support or Funding InformationNational Institutes of Health (R01 HL130783)

Diagnosis of Mucopolysaccharidoses.

The mucopolysaccharidoses (MPSs) include 11 different conditions caused by specific enzyme deficiencies in the degradation pathway of glycosaminoglycans (GAGs). Although most MPS types present increased levels of GAGs in tissues, including blood and urine, diagnosis is challenging as specific enzyme assays are needed for the correct diagnosis. Enzyme assays are usually performed in blood, with some samples (as leukocytes) providing a final diagnosis, while others (such as dried blood spots) still being considered as screening methods. The identification of variants in the specific genes that encode each MPS-related enzyme is helpful for diagnosis confirmation (when needed), carrier detection, genetic counseling, prenatal diagnosis (preferably in combination with enzyme assays) and phenotype prediction. Although the usual diagnostic flow in high-risk patients starts with the measurement of urinary GAGs, it continues with specific enzyme assays and is completed with mutation identification; there is a growing trend to have genotype-based investigations performed at the beginning of the investigation. In such cases, confirmation of pathogenicity of the variants identified should be confirmed by measurement of enzyme activity and/or identification and/or quantification of GAG species. As there is a growing number of countries performing newborn screening for MPS diseases, the investigation of a low enzyme activity by the measurement of GAG species concentration and identification of gene mutations in the same DBS sample is recommended before the suspicion of MPS is taken to the family. With specific therapies already available for most MPS patients, and with clinical trials in progress for many conditions, the specific diagnosis of MPS as early as possible is becoming increasingly necessary. In this review, we describe traditional and the most up to date diagnostic methods for mucopolysaccharidoses.

Vestronidase alfa: Recombinant human β-glucuronidase as an enzyme replacement therapy for MPS VII

Mucopolysaccharidosis VII (MPS VII) is a rare lysosomal storage disease characterized by a deficiency in the enzyme β-glucuronidase that has previously been successfully treated in a mouse model with enzyme replacement therapy. Here, we present the generation of a novel, highly sialylated version of recombinant human β-glucuronidase (rhGUS), vestronidase alfa, that has high uptake, resulting in an improved enzyme replacement therapy for the treatment of patients with MPS VII. In vitro, vestronidase alfa has 10-fold more sialic acid per mole of rhGUS monomer than a prior rhGUS version (referred to as GUS 43/44) and demonstrated very high affinity at ~1 nM half maximal uptake in human MPS VII fibroblasts. Vestronidase alfa has a longer enzymatic half-life after uptake into fibroblasts compared with other enzymes used as replacement therapy for MPS (40 days vs 3 to 4 days, respectively). In pharmacokinetic and tissue distribution experiments in Sprague-Dawley rats, intravenous administration of vestronidase alfa resulted in higher serum rhGUS levels and enhanced β-glucuronidase activity distributed to target tissues. Weekly intravenous injections of vestronidase alfa (0.1 mg/kg to 20 mg/kg) in a murine model of MPS VII demonstrated efficient enzyme delivery to all tissues, including bone and brain, as well as reduced lysosomal storage of glycosaminoglycans (GAGs) in a dose-dependent manner, resulting in increased survival after 8 weeks of treatment. Vestronidase alfa was well-tolerated and demonstrated no toxicity at concentrations that reached 5-times the proposed clinical dose. In a first-in-human phase 1/2 clinical trial, a dose-dependent reduction in urine GAG levels was sustained over 38 weeks of treatment with vestronidase alfa. Together, these results support the therapeutic potential of vestronidase alfa as an enzyme replacement therapy for patients with MPS VII.

A basic understanding of mucopolysaccharidosis: Incidence, clinical features, diagnosis, and management.

Mucopolysaccharidoses (MPS) are a group of rare lysosomal storage diseases (LSD) with multi-organic and severe symptoms. MPS occur worldwide in various forms though have relative a low incidence. The prevalent type of MPS varies among different continents, indicating that it may be associated with region and ethnic background. Undegraded glycosaminoglycans (GAGs) induced by deficiency of enzymes are the primary cause of MPS. Clinical features differ depending on the specific enzyme deficiency including coarse facial features, cognitive retardation, hepatosplenomegaly, hernias, kyphoscoliosis, corneal clouding, etc. Symptoms of different types are usually similar especially MPS I and II, but may have distinguishable features such as severe neurological problems in MPS III and hydrops fetails in MPS VII. These clinical features contribute to diagnosis, but early and precisely diagnosis in the asymptomatic stage is imperative for better outcomes. Novel approaches including urinary and blood GAG test, enzyme assay and gene test help to diagnose MPS and to determine its subtype. Hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT) are conventional treatment for MPS, but are not effective at treating all MPS. Newer threatments, such as advanced ERT, gene therapy and substrate reduction therapy (SRT), improve therpeutic efficacy. In this review, we update information on the clinical manifestations, diagnosis, and treatment of the different forms of this disease in the hopes of stimulating further interest in MPS.

Intracerebroventricular cerliponase alfa for CLN2 disease: Clinical practice considerations from US clinics

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

Impact of extended post-HSCT enzyme replacement therapy (ERT) on linear growth in mucopolysaccharidosis type IH (MPS IH)

Maroteaux–Lamy syndrome (mucopolysaccharidosis type VI, MPS VI) is a rare progressive metabolic disorder characterized by coarse facial features, hepatosplenomegaly, restrictive pulmonary function, cardiac abnormalities and stiff joints. The disease is caused by a deficiency of the lysosomal enzyme N-acetyl galactosamine 4-sulfatase which leads to glycosaminoglycan (GAG) storage in various tissues. It presents as a clinical spectrum with varying disease progressions and severities. While the phases I/II/III studies proved the effectiveness of enzyme-replacement therapy (ERT) with recombinant human arylsulfatase B, long-term data are still scarce.Over treatment periods ranging from 1.3 to 5.4 years, this prospective open-label follow-up study in 11 Dutch mucopolysaccharidosis type VI patients (age 2–18 years) showed that ERT had significant positive effects on cardiac-wall diameters (IVSd and LVMI), left and right shoulder flexions (p < 0.001), liver size and spleen size (p < 0.001), urinary GAG excretion (p < 0.001), and the scales of quality of life (motor functioning and body functioning). ERT did not affect cardiac valve regurgitation or hearing function; HRQoL decreased slightly in two domains (‘anxiety’ and ‘negative emotions’), and patients with the rapid and slow progressive forms of the disease differed with regard to baseline GAG excretion and GAG decrease during treatment.In conclusion, ERT had an effect on several clinical parameters. This effect was established in an open cohort of young mucopolysaccharidosis type VI patients.

Mucopolysaccharidoses : quand y penser ?

Mucopolysaccharidosis are lysosomal storage diseases, secondary to the accumulation of mucopolysaccharides. Type 1 mucopolysaccharidosis is the most common form and affects between 0.69 and 1.66 newborns per 100,000. The severity of mucopolysaccharidosis is variable with lethal forms in utero and attenuated forms diagnosed in adults. The most common symptoms are short stature, facial dysmorphism, chronic articular pains that can mimic chronic inflammatory rheumatism, axial and peripheral bone involvement, hepatosplenomegaly and an early carpal tunnel. Depending on the type of mucopolysaccharidosis, corneal, cerebral or cardiac involvements are possible. Screening is based on the analysis of urinary glycosaminoglycans. The deficient enzyme assay and the gene analysis confirm the diagnosis. Mucopolysaccharidosis recognition is important for patient management and family screening. In addition, specific enzyme replacement therapy exists for certain types of mucopolysaccharidosis. Role of clinician is important to evoke and diagnose mucopolysaccharidosis.

The long-term safety and efficacy of vestronidase alfa, rhGUS enzyme replacement therapy, in subjects with mucopolysaccharidosis VII

Vestronidase alfa (recombinant human beta-glucuronidase) is an enzyme replacement therapy (ERT) for Mucopolysaccharidosis (MPS) VII, a highly heterogeneous, ultra-rare disease. Twelve subjects, ages 8–25 years, completed a Phase 3, randomized, placebo-controlled, blind-start, single crossover study (UX003-CL301; NCT02377921), receiving 24–48 weeks of vestronidase alfa 4 mg/kg IV. All 12 subjects completed the blind-start study, which showed significantly reduced urinary glycosaminoglycans (GAG) and clinical improvement in a multi-domain responder index, and enrolled in a long-term, open-label, extension study (UX003-CL202; NCT02432144). Here, we report the final results of the extension study, up to an additional 144 weeks after completion of the blind-start study.Three subjects (25%) completed all 144 weeks of study, eight subjects (67%) ended study participation before Week 144 to switch to commercially available vestronidase alfa, and one subject discontinued due to non-compliance after receiving one infusion of vestronidase alfa in the extension study. The safety profile of vestronidase alfa in the extension study was consistent with observations in the preceding blind-start study, with most adverse events mild to moderate in severity. There were no treatment or study discontinuations due to AEs and no noteworthy changes in a standard safety chemistry panel. Out of the eleven subjects who tested positive for anti-drug antibodies at any time during the blind-start or extension study, including the baseline assessment in the blind-start study, seven subjects tested positive for neutralizing antibodies and all seven continued to demonstrate a reduction in urinary GAG levels. There was no association between antibody formation and infusion associated reactions.Subjects receiving continuous vestronidase alfa treatment showed a sustained urinary GAG reduction and clinical response evaluated using a multi-domain responder index that includes assessments in pulmonary function, motor function, range of motion, mobility, and visual acuity. Reduction in fatigue was also maintained in the overall population. As ERT is not expected to cross the blood brain barrier, limiting the impact on neurological signs of disease, and not all subjects presented with neurological symptoms, outcomes related to central nervous system pathology are not focused on in this report.Results from this study show the long-term safety and durability of clinical efficacy in subjects with MPS VII with long-term vestronidase alfa treatment.

Newborn screening for lysosomal disorders in Brazil: A pilot study using customized fluorimetric assays.

Lysosomal storage disorders (LSDs) are a group of genetic disorders characterized by deficiency of specific lysosomal enzymes. In general, patients are clinically normal at birth, and progressively develop severe signs and symptoms. Diagnosis is usually made several years after onset of manifestations, preventing patients to have the benefits of the early treatment. Newborn screening programs are being considered for LSDs to allow early diagnosis and treatment. The present study evaluated the feasibility of a customized screening approach based on modified fluorometric assays with reduced amounts of reagents, substrates and samples for: mucopolysaccharidosis (MPS) type I (MPS I), MPS VI, Fabry, Gaucher, and Pompe diseases. We also evaluated the advantages of including blood chitotriosidase and urinary glycosaminoglycans in the protocol. By the measurement of the specific disease-associated enzymes (plus blood chitotriosidase and urinary glycosaminoglycans) we analyzed 834 de-identified DBS of unselected newborns. No positive case was detected, and the false-positive rates were low. Taking into consideration the limitations of this methodology, we believe that, after defining proper cutoffs, it could be a viable alternative to provide NBS for LSDs by laboratories that may not be able to afford the commercial methods available.