Search Results (17)

Mucopolysaccharidosis type IIIC is a neurodegenerative lysosomal storage disorder (LSD) characterized by the accumulation of undegraded heparan sulfate (HS) due to the lack of an enzyme responsible for its degradation: acetyl-CoA:α-glucosaminide N-acetyltransferase (HGSNAT). Classical treatments are ineffective. Here, we attempt a new approach in genetic medicine, genetic substrate reduction therapy (gSRT), to counteract this neurological disorder. Briefly, we used synthetic oligonucleotides, particularly gapmer antisense oligonucleotides (ASOs), to target the synthesis of the accumulated compounds at the molecular level, downregulating a specific gene involved in the first step of HS biosynthesis, XYLT1. Our goal was to reduce HS production and, consequently, its accumulation. Initially, five gapmer ASOs were designed and their potential to decrease XYLT1 mRNA levels were tested in patient-derived fibroblasts. Subsequent analyses focused on the two best performing molecules alone. The results showed a high inhibition of the XYLT1 gene mRNA (around 90%), a decrease in xylosyltransferase I (XT-I) protein levels and a reduction in HS storage 6 and 10 days after transfection (up to 21% and 32%, respectively). Overall, our results are highly promising and may represent the initial step towards the development of a potential therapeutic option not only for MPS IIIC, but virtually for every other MPS III form. Ultimately, the same principle may also apply to other neuropathic MPS. Full article

Mucopolysaccharidosis (MPS) comprises a group of inherited metabolic diseases. Each MPS type is caused by a deficiency in the activity of one kind of enzymes involved in glycosaminoglycan (GAG) degradation, resulting from the presence of pathogenic variant(s) of the corresponding gene. All types/subtypes of MPS, which are classified on the basis of all kinds of defective enzymes and accumulated GAG(s), are severe diseases. However, neuronopathy only occurs in some MPS types/subtypes (specifically severe forms of MPS I and MPS II, all subtypes of MPS III, and MPS VII), while in others, the symptoms related to central nervous system dysfunctions are either mild or absent. The early diagnosis of neuronopathy is important for the proper treatment and/or management of the disease; however, there are no specific markers that could be easily used for this in a clinical practice. Therefore, in this work, a comparative analysis of shared and specific gene expression alterations in neuronopathic and non-neuronopathic MPS types was performed using cultures of cells derived from patients. Using transcriptomic analyses (based on the RNA-seq method, confirmed by measuring the levels of a selected gene product), we identified genes (including PFN1, ADAMTSL1, and ABHD5) with dysregulated expression that are common for all, or almost all, types of MPS, suggesting their roles in MPS pathogenesis. Moreover, a distinct set of genes (including ARL6IP6 and PDIA3) exhibited expression changes only in neuronopathic MPS types/subtypes, but not in non-neuronopathic ones, suggesting their possible applications as biomarkers for neurodegeneration in MPS. These findings provide new insights into both the molecular mechanisms of MPS pathogenesis and the development of differentiation method(s) between neuronopathic and non-neuronopathic courses of the disease. Full article

Sanfilippo syndrome, or mucopolysaccharidosis type III (MPS III), is a rare lysosomal disease caused by congenital enzymatic deficiencies in heparan sulfate (HS) degradation, leading to organ dysfunction. The most severe hallmark of MPS III comprises neurological alterations, although gastrointestinal symptoms (GISs) have also been shown to be relevant in many patients. Here, we explored the contribution of the gut microbiota to MPS III GISs. We analyzed the composition and functionality of the gut microbiota in two MPS III siblings with the same mutation (c.544C > T, c.1080delC, in the SGSH gene) and the same diet, but with differences in their GISs, including recurrent diarrhea in one of them. Using 16S sequencing, we observed that the MPS III patients exhibited decreased alpha diversity and a lower abundance of Lachnospiraceae and Bifidobacteriaceae accompanied by a higher abundance of the Ruminococcaceae and Rikenellaceae families than the healthy control subjects. Comparing siblings, we found an increased abundance of Bacteroidaceae and a lower abundance of Ruminococcaceae and Akkermansiaceae in the GIS-free patient. This patient also had a higher relative abundance of Sus genes (SusA, SusB, SusE, and SusG) involved in glycosaminoglycan metabolism. We found higher HS levels in the stool of the two MPS III patients than in healthy volunteers, particularly in the patient with GISs. Functionally, whole fecal metabolites from the patient with GISs induced oxidative stress in vitro in healthy monocytes. Finally, the Bacteroides thetaiotaomicron strain isolated from MPS III stool samples exhibited HS degradation ability. Overall, our results reveal different microbiota compositions and functionalities in MPS III siblings, who exhibited differential gastrointestinal symptomatology. Our study may serve as a gateway to explore the impact of the gut microbiota and its potential to enhance the quality of life in Sanfilippo syndrome patients. Full article

Mucopolysaccharidosis III type C (MPS IIIC) is an untreatable neuropathic lysosomal storage disease caused by a genetic deficiency of the lysosomal N-acetyltransferase, HGSNAT, catalyzing a transmembrane acetylation of heparan sulfate. HGSNAT is a transmembrane enzyme incapable of free diffusion between the cells or their cross-correction, which limits development of therapies based on enzyme replacement and gene correction. Since our previous work identified neuroinflammation as a hallmark of the CNS pathology in MPS IIIC, we tested whether it can be corrected by replacement of activated brain microglia with neuroprotective macrophages/microglia derived from a heterologous HSPC transplant. Eight-week-old MPS IIIC (Hgsnat^P304L) mice were transplanted with HSPC from congenic wild type mice after myeloablation with Busulfan and studied using behavior test battery, starting from the age of 6 months. At the age of ~8 months, mice were sacrificed to study pathological changes in the brain, heparan sulfate storage, and other biomarkers of the disease. We found that the treatment corrected several behavior deficits including hyperactivity and reduction in socialization, but not memory decline. It also improved several features of CNS pathology such as microastroglyosis, expression of pro-inflammatory cytokine IL-1β, and accumulation of misfolded amyloid aggregates in cortical neurons. At the periphery, the treatment delayed development of terminal urinary retention, potentially increasing longevity, and reduced blood levels of heparan sulfate. However, we did not observe correction of lysosomal storage phenotype in neurons and heparan sulfate brain levels. Together, our results demonstrate that neuroinflammation in a neurological lysosomal storage disease, caused by defects in a transmembrane enzyme, can be effectively ameliorated by replacement of microglia bearing the genetic defect with cells from a normal healthy donor. They also suggest that heterologous HSPC transplant, if used together with other methods, such as chaperone therapy or substrate reduction therapy, may constitute an effective combination therapy for MPS IIIC and other disorders with a similar etiology. Full article

Sanfilippo syndrome Type-B, also known as mucopolysaccharidosis IIIB (MPS IIIB), accounts for approximately one-third of all Sanfilippo syndrome patients and is characterized by a similar natural history as Type-A. Patients suffer from developmental regression, bone malformation, organomegaly, GI distress, and profound neurological deficits. Despite human trials of enzyme replacement therapy (ERT) (SBC-103, AX250) in MPS IIIB, there is currently no FDA approved treatment and a few palliative options. The major concerns of ERT and gene therapy for the treatment of bone malformation are the inadequate biodistribution of the missing enzyme, N-acetyl-α-glucosaminidase (NAGLU), and that the skeleton is a poorly hit target tissue in ERT and gene therapy. Each of the four known human types of MPS III (A, B, C, and D) is usually regarded as having mild bone manifestations, yet it remains poorly characterized. This study aimed to determine bone mineral content (BMC), volumetric bone mineral density (vBMD), and biomechanical properties in femurs MPS IIIB C57BL/6 mice compared to phenotypic control C57BL/6 mice. Significant differences were observed in MPS IIIB mice within various cortical and cancellous bone parameters for both males and females (p < 0.05). Here, we establish some osteogenic manifestations of MPS IIIB within the mouse model by radiographic and biomechanical tests, which are also differentially affected by age and sex. This suggests that some skeletal features of the MPS IIIB mouse model may be used as biomarkers of peripheral disease correction for preclinical treatment of MPS IIIB. Full article

Mucopolysaccharidosis (MPS) is a group of rare metabolic diseases associated with reduced life expectancy and a substantial unmet medical need. Immunomodulatory drugs could be a relevant treatment approach for MPS patients, although they are not licensed for this population. Therefore, we aim to provide evidence justifying fast access to innovative individual treatment trials (ITTs) with immunomodulators and a high-quality evaluation of drug effects by implementing a risk–benefit model for MPS. The iterative methodology of our developed decision analysis framework (DAF) consists of the following steps: (i) a comprehensive literature analysis on promising treatment targets and immunomodulators for MPS; (ii) a quantitative risk–benefit assessment (RBA) of selected molecules; and (iii) allocation phenotypic profiles and a quantitative assessment. These steps allow for the personalized use of the model and are in accordance with expert and patient representatives. The following four promising immunomodulators were identified: adalimumab, abatacept, anakinra, and cladribine. An improvement in mobility is most likely with adalimumab, while anakinra might be the treatment of choice for patients with neurocognitive involvement. Nevertheless, a RBA should always be completed on an individual basis. Our evidence-based DAF model for ITTs directly addresses the substantial unmet medical need in MPS and characterizes a first approach toward precision medicine with immunomodulatory drugs. Full article

Background: Mucopolysaccharidosis type III (MPS III) is an autosomal recessive lysosomal storage disorder characterised by progressive neurocognitive deterioration. MPS III subtypes are clinically indistinguishable, with a wide range of symptoms and variable severity. The natural history of this disorder within an Asian population has not yet been extensively studied. This study investigated the natural history of Korean patients with MPS III. Methods: Thirty-four patients from 31 families diagnosed with MPS III from January 1997 to May 2020 in Samsung Medical Centre were enrolled. Clinical, molecular, and biochemical characteristics were retrospectively collected from the patients’ medical records and via interviews. Results: 18 patients had MPS IIIA, 14 had IIIB, and two had IIIC. Twenty (58.9%) patients were male. Mean age at symptom onset was 2.8 ± 0.8 years and at diagnosis was 6.3 ± 2.2 years. All patients with MPS IIIA and IIIB were classified into the rapidly progressing (RP) phenotype. The most common symptom at diagnosis was language retardation (88.2%), followed by motor retardation (76.5%), general retardation (64.7%), and hyperactivity (41.2%). Language retardation was more predominant in IIIA, and motor retardation was more predominant in IIIB. The mean age of the 13 deceased patients at the time of the study was 14.4 ± 4.1 years. The age at diagnosis and lag time were significantly older and longer in the non-survivor group compared with the survivor group (p = 0.029 and 0.045, respectively). Genetic analysis was performed in 24 patients with MPS III and identified seven novel variants and three hot spots. Conclusion: This study is the first to analyse the genetic and clinical characteristics of MPS III patients in Korea. Better understanding of the natural history of MPS III might allow early diagnosis and timely management of the disease and evaluation of treatment outcomes in future clinical trials for MPS III. Full article

Background: Mucopolysaccharidosis (MPS) is a rare congenital lysosomal storage disorder with complex airways. High anterior larynx is assessed by thyromental distance (TMD) nasendoscopy. A simpler method to assess this hyoid bone is described. The distance between the central-hyoid and symphysis of the mandible (hyo-mental distance; HMD) and inclination of this line to the horizontal axis (hyo-mental angle; HMA) in neutrally positioned patients is investigated. Methods: HMA, HMD in MPS, and non-MPS were compared, and their correlation with height and weight were assessed. Results: 50 adult MPS patients (M = 32, F = 18, age range = 19–66 years; mean BMI = 26.8 kg/m²) of MPS I, II, III, IV, and VI were compared with 50 non-MPS (M = 25, F = 25; age range = 22–84 years; mean BMI = 26.5 kg/m²). Mean HMA in MPS was 25.72° (−10 to +50) versus 2.42° (−35 to +28) in non-MPS. Mean HMD was 46.5 (25.7–66) millimeters in MPS versus 41.8 (27–60.3) in non-MPS. HMA versus height and weight showed a moderate correlation (r = −0.4, p < 0.05) in MPS and no significant correlation (r < 0.4, p > 0.05) in non-MPS. HMD versus height and weight showed no correlation (r < 0.4, p > 0.05) in both groups. Conclusions: HMA seems more acute in MPS despite nearly the same HMD as non-MPS, signifying a high larynx, which may be missed by TMD. Full article

Background: Mucopolysaccharidosis type III (MPS III, Sanfilippo disease) is a life-limiting recessive lysosomal storage disorder caused by a deficiency in the enzymes involved in degrading glycosaminoglycan heparan sulfate. MPS III is characterized by progressive deterioration of the central nervous system. Respiratory tract infections have been reported as frequent and as the most common cause of death, but gastrointestinal (GI) manifestations have not been acknowledged as a cause of concern. The aim of this study was to determine the incidence of GI problems as a primary cause of death and to review GI symptoms reported in published studies. Methods: Causes of death from 221 UK death certificates (1957–2020) were reviewed and the literature was searched to ascertain reported GI symptoms. Results: GI manifestations were listed in 5.9% (n = 13) of death certificates. Median (IQR) age at death was 16.7 (5.3) years. Causes of death included GI failure, GI bleed, haemorrhagic pancreatitis, perforation due to gastrostomies, paralytic ileus and emaciation. Twenty-one GI conditions were reported in 30 studies, mostly related to functional GI disorders, including diarrhoea, dysphagia, constipation, faecal incontinence, abdominal pain/distension and cachexia. Conclusions: GI manifestations may be an under-recognized but important clinical feature of MPS III. Early recognition of GI symptoms and timely interventions is an important part of the management of MPS III patients. Full article

(1) Background: Mucopolysaccharidoses (MPS) are a heterogeneous group of lysosomal storage disorders caused by the absence of enzymes required for degradation of glycosaminoglycans (GAGs). GAGs deposition in tissues leads to progressive airway narrowing and/or tortuosity. Increased longevity of patients has posed newer problems, especially the airway. This study aims to characterise various airway abnormalities in adult MPS from a regional centre and proposes a method to quantify the severity of the airway disease. (2) Methods: Retrospective analysis by case notes review, clinical examination, endoscopy, cross-sectional imaging, 3-dimensional reconstruction, and physiological investigations were used to assess the airway abnormalities. Quantitative assessment of the airway severity was performed a validated questionnaire of 15 parameters to derive Salford Mucopolysaccharidosis Airway Score (SMAS). (3) Results: Thirty-one adult MPS patients (21M/ 9F; median 26.7 years; range 19–42 years) were reviewed. There were 9 MPS I, 12 MPS II, 2 MPS III, 5 MPS IV, 2 MPS VI, and 1 MPS VII. Airway abnormalities in each MPS type are described. Patients scoring more than 35 on SMAS had some form of airway intervention. The area under curve of 0.9 was noted at a score of 25, so SMAS more than 25 may predict a difficult airway and potential to have complications. Pearson’s correlation between SMAS and height, weight, BMI were poor (p < 0.05). (4) Conclusions: Airway abnormalities in adult MPS are varied and complex. Assessment of the airway should be holistic and include multiple parameters. An objective multidimensional score such as SMAS may help to predict and manage difficult airways warranting further investigation and validation. Full article

Background: Cardiovascular abnormalities have been observed in patients with mucopolysaccharidosis (MPS) of any type, with the most documented abnormalities being valvular regurgitation and stenosis and cardiac hypertrophy. Only a few studies have focused on aortic root dilatation and the long-term effects of enzyme replacement therapy (ERT) in these patients. Methods: We reviewed echocardiograms of 125 Taiwanese MPS patients (age range, 0.1 to 19.1 years; 11 with MPS I, 49 with MPS II, 25 with MPS III, 29 with MPS IVA, and 11 with MPS VI). The aortic root diameter was measured at the sinus of Valsalva. Results: Aortic root dilatation (z score >2) was observed in 47% of the MPS patients, including 66% of MPS IV, 51% of MPS II, 45% of MPS VI, 28% of MPS III, and 27% of MPS I patients. The mean aortic root diameter z score was 2.14 (n = 125). The patients with MPS IV had the most severe aortic root dilatation with a mean aortic root diameter z score of 3.03, followed by MPS II (2.12), MPS VI (2.06), MPS III (1.68), and MPS I (1.03). The aortic root diameter z score was positively correlated with increasing age (n = 125, p < 0.01). For the patients with MPS II, III, and IV, aortic root diameter z score was also positively correlated with increasing age (p < 0.01). For 16 patients who had received ERT and had follow-up echocardiographic data (range 2.0–16.2 years), the mean aortic root diameter z score change was −0.46 compared to baseline (baseline 2.49 versus follow-up 2.03, p = 0.490). Conclusions: Aortic root dilatation was common in the patients with all types of MPS, with the most severe aortic root dilatation observed in those with MPS IV. The severity of aortic root dilatation worsened with increasing age, reinforcing the concept of the progressive nature of this disease. ERT for MPS appears to stabilize the progression of aortic root dilatation. Full article

Newborn screening (NBS) for mucopolysaccharidosis type I (MPS I, Hurler syndrome) is currently conducted in about two-fifths of the NBS programs in the United States and in a few other countries. Screening is performed by measurement of residual activity of the enzyme alpha-l-iduronidase in dried blood spots using either tandem mass spectrometry or digital microfluidic fluorometry (DMF). In this article, we focus on the development and practical experience of using DMF to screen for MPS I in the USA. By means of their responses to a questionnaire, we determined for each responding program that is screening for MPS I using DMF the screen positive rate, follow-up methods, and classification of confirmed cases as either severe or attenuated. Overall, the results show that at the time of reporting, over 1.3 million newborns in the US were screened for MPS I using DMF, 2094 (0.173%) of whom were screen positive. Of these, severe MPS I was confirmed in five cases, attenuated MPS I was confirmed in two cases, and undetermined phenotype was reported in one case. We conclude that DMF is an effective and economical method to screen for MPS I and recommend second-tier testing owing to high screen positive rates. Preliminary results of NBS for MPS II and MPS III using DMF are discussed. Full article

Background: Children with mucopolysaccharidosis (MPS) generally appear unaffected at birth but may develop multiple clinical manifestations including profound growth impairment as they grow older. Each type of MPS has a variable age at onset and variable rate of progression, however, information regarding growth in Asian children is limited. Methods: This retrospective analysis included 129 Taiwanese patients with MPS (age range, 0.7 to 19.5 years, median age, 7.9 years) from eight medical centers in Taiwan from January 1996 through December 2018. Results: The mean z scores for the first recorded values of height, weight, and body mass index in the patients’ medical records were −4.25, −1.04, and 0.41 for MPS I (n = 9), −2.31, 0.19, and 0.84 for MPS II (n = 49), −0.42, 0.08, and −0.12 for MPS III (n = 27), −6.02, −2.04, and 0.12 for MPS IVA (n = 30), and −4.46, −1.52, and 0.19 for MPS VI (n = 14), respectively. MPS IVA had the lowest mean z scores for both height and weight among all types of MPS, followed by MPS VI, MPS I, MPS II, and MPS III, which showed the mildest growth retardation. Both z scores for height and weight were negatively correlated with increasing age for all types of MPS (p < 0.01). Of 32 patients younger than 5 years of age, 16 (50%), and 23 (72%) had positive z scores of height and weight, respectively. A substantial number of younger patients with MPS I, II, III, and IVA had a positive height z score. The median age at diagnosis was 3.9 years (n = 115). Conclusions: The patients with MPS IVA had the most significant growth retardation among all types of MPS, followed by MPS VI, MPS I, MPS II, and MPS III. The height and weight of the MPS patients younger than 2–5 years of age were higher than those of healthy individuals, however, their growth significantly decelerated in subsequent years. Understanding the growth curve and potential involved in each type of MPS may allow for early diagnosis and timely management of the disease, which may improve the quality of life. Full article

Obstacles to effective therapies for mucopolysaccharidoses (MPSs) determine the need for continuous studies in order to enhance therapeutic strategies. Dimethyl sulfoxide (DMSO) is frequently utilised as a solvent in biological studies, and as a vehicle for drug therapy and the in vivo administration of water-insoluble substances. In the light of the uncertainty on the mechanisms of DMSO impact on metabolism of glycosaminoglycans (GAGs) pathologically accumulated in MPSs, in this work, we made an attempt to investigate and resolve the question of the nature of GAG level modulation by DMSO, the isoflavone genistein solvent employed previously by our group in MPS treatment. In this work, we first found the cytotoxic effect of DMSO on human fibroblasts at concentrations above 3%. Also, our results displayed the potential role of DMSO in the regulation of biological processes at the transcriptional level, then demonstrated a moderate impact of the solvent on GAG synthesis. Interestingly, alterations of lysosomal ultrastructure upon DMSO treatment were visible. As there is growing evidence in the literature that DMSO can affect cellular pathways leading to numerous changes, it is important to expand our knowledge concerning this issue. Full article

Mucopolysaccharidosis III type A (MPS IIIA; Sanfilippo syndrome), a genetic lysosomal disorder causing a deficiency of heparan N-sulfatase (HNS), leads to progressive cognitive decline from an early age. An effective enzyme replacement therapy (ERT) for MPS IIIA requires central nervous system (CNS) biodistribution. Recombinant human heparan N-sulfatase (rhHNS), an investigatory ERT for MPS IIIA, has been formulated for intrathecal (IT) administration since intravenous (IV) administration cannot cross the blood brain barrier (BBB) in sufficient amounts to have a therapeutic effect. In this study, systemic and CNS distribution of rhHNS in cynomolgus monkeys following IV and IT administration was evaluated by quantitation of rhHNS in serum, cerebral spinal fluid (CSF) and various tissues, and positron emission tomography (PET) imaging of live animals. Following IV administration, rhHNS levels were low to non-detectable in the CSF, and systemic clearance was rapid (≤2 h). With IT administration, rhHNS was observable in CNS tissues in ≤1 h, with varying T_max (1–24 h). Appreciable systemic distribution was observed up to 7 days. This provides evidence that in this animal model, intrathecal administration of rhHNS delivers the replacement enzyme to therapeutically relevant tissues for the treatment of Sanfilippo Syndrome type A. Penetration into grey matter and cortex was 3–4 times greater than concentrations in white matter and deeper parenchymal regions, suggesting some limitations of this ERT strategy. Full article