Iduronate-2-sulfatase Research Articles

Hematopoietic Stem Cell Transplantation in Mucopolysaccharidosis Type II

Mucopolysaccharidosis II (MPS II—Hunter syndrome) is an X-linked lysosomal storage disorder caused by a deficiency in iduronate-2 sulfatase. Enzyme replacement therapy does not cross the blood–brain barrier (BBB), limiting the results in neurological forms of the disease. Another treatment option for MPS, hematopoietic stem cell transplantation (HSCT) has become the treatment of choice for the severe form of MPS I since it can preserve neurocognition when performed early in the course of the disease. Even though the intravenous therapy does not cross the BBB, it has become the recommended treatment for MPS II, and HSCT was not often indicated. In an attempt to understand why this treatment modality is rejected by most specialists as a treatment option for patients with Hunter syndrome, we sought to raise all HSCT cases already reported in the scientific literature. Databases used were Medline/PubMed, Lilacs/BVS Cochrane Library, DARE, SciELO, and SCOPUS. Different combinations of the terms “mucopolysaccharidosis II,” “Hunter syndrome,” “hematopoietic stem cell transplantation,” “bone marrow transplantation,” and “umbilical cord blood stem cell transplantation” were used. A total of 780 articles were found. After excluding redundant references and articles not related to the theme, 26 articles were included. A descriptive summary of each article is presented, and the main features are summed up. The clinical experience with HSCT in MPS II is small, and most of the available literature is outdated. The available data reveal poor patient selection criteria, varied conditioning regimens, distinct follow-up parameters, and post-HSCT outcomes of interest, making impossible to compare and generalize the results obtained. Recently, after the development of new conditioning protocols and techniques and the creation of bone marrow donor registries and umbilical cord banks, HSCT has become more secure and accessible. It seems now appropriate to reconsider HSCT as a treatment option for the neuronopathic form of MPS II.

Quantification of the enzyme activities of iduronate-2-sulfatase, N-acetylgalactosamine-6-sulfatase and N-acetylgalactosamine-4-sulfatase using liquid chromatography-tandem mass spectrometry

Mucopolysaccharidosis (MPS) is a genetic disorder characterized by the accumulation of glycosaminoglycans in the body. Of the multiple MPS disease subtypes, several are caused by defects in sulfatases. Specifically, a defect in iduronate-2-sulfatase (ID2S) leads to MPS II, whereas N-acetylgalactosamine-6-sulfatase (GALN) and N-acetylgalactosamine-4-sulfatase (ARSB) defects relate to MPS IVA and MPS VI, respectively. A previous study reported a combined assay for these three disorders in a 96-well plate using a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based technique (Kumar et al., Clin Chem 2015 61(11):1363-1371). In our study, we applied this methodology to a Japanese population to examine the assay precision and the separation of populations between disease-affected individuals and controls for these three disorders. Within our assay conditions, the coefficient of variation (CV, %) values for an interday assay of ID2S, GALN, and ARSB were 9%, 18%, and 9%, respectively (n=7). The average enzyme activities of ID2S, GALN, and ARSB in random neonates were 19.6±5.8, 1.7±0.7, and 13.4±5.2μmol/h/L (mean±SD, n=240), respectively. In contrast, the average enzyme activities of ID2S, GALN, and ARSB in disease-affected individuals were 0.5±0.2 (n=6), 0.3±0.1 (n=3), and 0.3 (n=1) μmol/h/L, respectively. The representative analytical range values corresponding to ID2S, GALN, and ARSB were 39, 17, and 168, respectively. These results raise the possibility that the population of disease-affected individuals could be separated from that of healthy individuals using the LC-MS/MS-based technique.

Chaperone effect of sulfated disaccharide from heparin on mutant iduronate-2-sulfatase in mucopolysaccharidosis type II.

Small molecules called pharmacological chaperones have been shown to improve the stability, intracellular localization, and function of mutated enzymes in several lysosomal storage diseases, and proposed as promising therapeutic agents for them. However, a chaperone compound for mucopolysaccharidosis type II (MPS II), which is an X-linked lysosomal storage disorder characterized by a deficiency of iduronate-2-sulfatase (IDS) and the accumulation of glycosaminoglycans (GAGs), has still not been developed. Here we focused on the Δ-unsaturated 2-sulfouronic acid-N-sulfoglucosamine (D2S0), which is a sulfated disaccharide derived from heparin, as a candidate compound for a pharmacological chaperone for MPS II, and analyzed the chaperone effect of the saccharide on IDS by using recombinant protein and cells expressing mutated enzyme. When D2S0 was incubated with recombinant human IDS (rhIDS) in vitro, the disaccharide attenuated the thermal degeneration of the enzyme. This effect of D2S0 on the thermal degeneration of rhIDS was enhanced in a dose-dependent manner. D2S0 also increased the residual activity of mutant IDS in patient fibroblasts. Furthermore, D2S0 improved the enzyme activity of IDS mutants derived from six out of seven different mutations in HEK293T cells transiently expressing them. These results indicate that D2S0 is a potential pharmacological chaperone for MPS II.

Neural cells generated from human induced pluripotent stem cells as a model of CNS involvement in mucopolysaccharidosis type II.

Mucopolysaccharidosis type II (MPSII) is a rare X-linked lysosomal storage disorder caused by mutations in the iduronate-2-sulfatase (IDS) gene (IDS, Xq28). MPSII is characterized by skeletal deformities, hearing loss, airway obstruction, hepatosplenomegaly, cardiac valvular disease, and progressive neurological impairment. At the cellular level, IDS deficiency leads to lysosomal storage of glycosaminoglycans (GAGs), dominated by accumulation of dermatan and heparan sulfates. Human induced pluripotent stem cells (iPSC) represent an alternative system that complements the available MPSII murine model. Herein we report on the reprogramming of peripheral white blood cells from male and female MPSII patients into iPSC using a non-integrating protocol based on the Sendai virus vector system. We differentiated the iPSC lines into IDS deficient and GAG accumulating β-Tubulin III+ neurons, GFAP+ astrocytes, and CNPase+ oligodendrocytes. The lysosomal system in these cells displayed structural abnormalities reminiscent of those previously found in patient tissues and murine IDS deficient neuronal stem cells. Furthermore, quantitative determination of GAGs revealed a moderate increase in GAG levels in IDS deficient neurons and glia. We also tested the effects of recombinant IDS and found that the exogenous enzyme was internalized from the culture media and partially decreased the intracellular GAG levels in iPSC-derived neural cells; however, it failed to completely prevent accumulation of GAGs. In summary, we demonstrate that this human iPSC based model expresses the cellular and biochemical features of MPSII, and thus represents a useful experimental tool for further pathogenesis studies as well as therapy development and testing.

Clinical outcomes in idursulfase-treated patients with mucopolysaccharidosis type II: 3-year data from the hunter outcome survey (HOS)

BackgroundMucopolysaccharidosis type II (MPS II; Hunter syndrome) is a rare, X-linked disorder caused by deficient activity of the enzyme iduronate-2-sulfatase (I2S). Treatment is available in the form of enzyme replacement therapy (ERT) with recombinant I2S. Clinical outcomes following ≥3 years of ERT with idursulfase were investigated in a broad population of patients with MPS II enrolled in the Hunter Outcome Survey (HOS).MethodsAs of January 2016, 639 patients (excluding female patients, individuals who had received a bone marrow transplant and those enrolled in the phase 1/2 [TKT018] or phase 2/3 [TKT024] clinical trial) followed prospectively in the registry had received idursulfase for ≥6 months. These individuals all had data available for ≥1 clinical parameter at baseline and ≥1 additional time point following treatment initiation. Changes in clinical parameters were assessed in the subcohorts of patients with a measurement at baseline and at year 1, 2 or 3 of treatment. Safety data from patients who started treatment at or after enrollment in HOS (n = 233) were also assessed.ResultsMedian (10th, 90th percentiles) age at first treatment was 6.2 (2.1, 18.2) years and median treatment duration was 56.3 (18.2, 97.6) months. Urinary glycosaminoglycan (uGAG) levels decreased from baseline to year 3 in patients with data available at this time point (median change from baseline: −201.0 [−591.4, −21.9] μg/mg creatinine [n = 121]). Improvements in the following parameters were observed at year 3 in the subcohorts: 6-min walking test (6MWT) distance, 10.6 (−33.6, 50.8)% (n = 26); left ventricular mass index (LVMI), −9.3 (−31.5, 19.7)% (n = 52); absolute forced vital capacity (FVC), 29.7 (−13.4, 66.7)% (n = 23); absolute forced expiratory volume in 1 s (FEV1), 22.8 (−15.2, 62.1) % (n = 22); palpable liver size, −54.5 (−85.7, 50.0)% (n = 53); palpable spleen size, −33.3 (−80.0, 33.3)% (n = 17). No new or unexpected safety concerns were identified in this analysis.ConclusionsThese findings suggest that idursulfase has a positive effect on uGAG levels, 6MWT results, LVMI, FVC, FEV1 and hepatosplenomegaly after 1, 2 and 3 years treatment.

AB092. A novel variant c.1506G>C at exon 9 of iduronate 2-sulfatase gene in mucopolysaccharidosis type II Indonesian child

AB092. A novel variant c.1506G>C at exon 9 of iduronate 2-sulfatase gene in mucopolysaccharidosis type II Indonesian child

Development of idursulfase therapy for mucopolysaccharidosis type II (Hunter syndrome): the past, the present and the future.

Mucopolysaccharidosis type II (MPS II; Hunter syndrome; OMIM 309900) is a rare, multisystemic, progressive lysosomal storage disease caused by deficient activity of the iduronate-2-sulfatase (I2S) enzyme. Accumulation of the glycosaminoglycans dermatan sulfate and heparan sulfate results in a broad range of disease manifestations that are highly variable in presentation and severity; notably, approximately two-thirds of individuals are affected by progressive central nervous system involvement. Historically, management of this disease was palliative; however, during the 1990s, I2S was purified to homogeneity for the first time, leading to cloning of the corresponding gene and offering a means of addressing the underlying cause of MPS II using enzyme replacement therapy (ERT). Recombinant I2S (idursulfase) was produced for ERT using a human cell line and was shown to be indistinguishable from endogenous I2S. Preclinical studies utilizing the intravenous route of administration provided valuable insights that informed the design of the subsequent clinical studies. The pivotal Phase II/III clinical trial of intravenous idursulfase (Elaprase®; Shire, Lexington, MA, USA) demonstrated improvements in a range of clinical parameters; based on these findings, intravenous idursulfase was approved for use in patients with MPS II in the USA in 2006 and in Europe and Japan in 2007. Evidence gained from post-approval programs has helped to improve our knowledge and understanding of management of patients with the disease; as a result, idursulfase is now available to young pediatric patients, and in some countries patients have the option to receive their infusions at home. Although ERT with idursulfase has been shown to improve somatic signs and symptoms of MPS II, the drug does not cross the blood–brain barrier and so treatment of neurological aspects of the disease remains challenging. A number of novel approaches are being investigated, and these may help to improve the care of patients with MPS II in the future.

Multiplex Tandem Mass Spectrometry Enzymatic Activity Assay for Newborn Screening of the Mucopolysaccharidoses and Type 2 Neuronal Ceroid Lipofuscinosis

We expanded the use of tandem mass spectrometry combined with liquid chromatography (LC-MS/MS) for multiplex newborn screening of seven lysosomal enzymes in dried blood spots (DBS). The new assays are for enzymes responsible for the mucopolysaccharidoses (MPS-I, -II, -IIIB, -IVA, -VI, and -VII) and type 2 neuronal ceroid lipofuscinosis (LINCL). New substrates were prepared and characterized for tripeptidyl peptidase 1 (TPP1), α-N-acetylglucosaminidase (NAGLU), and lysosomal β-glucuronidase (GUSB). These assays were combined with previously developed assays to provide a multiplex LC-MS/MS assay of 7 lysosomal storage diseases. Multiple reaction monitoring of ion dissociations for enzyme products and deuterium-labeled internal standards was used to quantify the enzyme activities. Deidentified DBS samples from 62 nonaffected newborns were analyzed to simultaneously determine (run time 2 min per DBS) the activities of TPP1, NAGLU, and GUSB, along with those for α-iduronidase (IDUA), iduronate-2-sulfatase (I2S), N-acetylgalactosamine-6-sulfatase (GALNS), and N-acetylgalactosamine-4-sulfatase (ARSB). The activities measured in the 7-plex format showed assay response-to-blank-activity ratios (analytical ranges) of 102-909 that clearly separated healthy infants from affected children. The new multiplex assay provides a robust comprehensive newborn screening assay for the mucopolysaccharidoses. The method has been expanded to include additional lysosomal storage diseases.

In vitrorecapitulation of the site-specific editing (to wild-type) of mutantIDSmRNA transcripts, and the characterization of IDS protein translated from the edited mRNAs

The transfer of genomic information into the primary RNA sequence can be altered by RNA editing. We have previously shown that genomic variants can be RNA-edited to wild-type. The presence of distinct "edited" iduronate 2-sulfatase (IDS) mRNA transcripts ex vivo evidenced the correction of a nonsense and frameshift variant, respectively, in three unrelated Hunter syndrome patients. This phenomenon was confirmed in various patient samples by a variety of techniques, and was quantified by single-nucleotide primer extension. Western blotting also confirmed the presence of IDS protein similar in size to the wild-type. Since preliminary experimental evidence suggested that the "corrected" IDS proteins produced by the patients were similar in molecular weight and net charge to their wild-type counterparts, an in vitro system employing different cell types was established to recapitulate the site-specific editing of IDS RNA (uridine to cytidine conversion and uridine deletion), and to confirm the findings previously observed ex vivo in the three patients. In addition, confocal microscopy and flow cytometry analyses demonstrated the expression and lysosomal localization in HEK293 cells of GFP-labeled proteins translated from edited IDS mRNAs. Confocal high-content analysis of the two patients' cells expressing wild-type or mutated IDS confirmed lysosomal localization and showed no accumulation in the Golgi or early endosomes.

Prevention of Neurocognitive Deficiency in Mucopolysaccharidosis Type II Mice by Central Nervous System-Directed, AAV9-Mediated Iduronate Sulfatase Gene Transfer.

Mucopolysaccharidosis type II (MPS II; Hunter syndrome) is a rare X-linked recessive lysosomal disorder caused by defective iduronate-2-sulfatase (IDS), resulting in accumulation of heparan sulfate and dermatan sulfate glycosaminoglycans (GAGs). Enzyme replacement is the only Food and Drug Administration-approved therapy available for MPS II, but it is expensive and does not improve neurologic outcomes in MPS II patients. This study evaluated the effectiveness of adeno-associated virus (AAV) vector encoding human IDS delivered intracerebroventricularly in a murine model of MPS II. Supraphysiological levels of IDS were observed in the circulation (160-fold higher than wild type) for at least 28 weeks post injection and in most tested peripheral organs (up to 270-fold) at 10 months post injection. In contrast, only low levels of IDS were observed (7-40% of wild type) in all areas of the brain. Sustained IDS expression had a profound effect on normalization of GAG in all tested tissues and on prevention of hepatomegaly. Additionally, sustained IDS expression in the central nervous system (CNS) had a prominent effect in preventing neurocognitive deficit in MPS II mice treated at 2 months of age. This study demonstrates that CNS-directed, AAV9 mediated gene transfer is a potentially effective treatment for Hunter syndrome, as well as other monogenic disorders with neurologic involvement.

Molecular analysis of the novel IDS allele in a Thai family with mucopolysaccharidosis type II: The c.928C>T (p.Gln310*) transcript is sensitive to nonsense-mediated mRNA decay.

Hunter syndrome (or mucopolysaccharidosis type II, MPS II) is an X-linked recessive disorder induced by a deficiency of the iduronate 2-sulfatase (IDS) enzyme, resulting in the accumulation of glycosaminoglycan substrates, heparan sulfate and dermatan sulfate, in the lysosomes. The progressive accumulation of undegraded metabolites induces cell and tissue dysfunction, leading to multi-systemic pathology. The heterogeneity of clinical phenotypes, ranging from mild to severe forms, results from different mutations in the IDS gene. To date, >550 MPS II causal mutations have been reported in the IDS gene, of which ~10% are nonsense mutations that lead to premature protein termination. In the present study, the IDS mutation causing MPS II in an extended Thai family was identified using IDS enzyme assay and IDS gene exon sequencing. Three family members were enzymatically confirmed to have MPS II and to carry the novel IDS nonsense allele c.928C>T (p.Gln310*). The IDS mRNA levels were evaluated by reverse transcription-quantitative polymerase chain reaction, which demonstrated that all patients exhibited a reduction of IDS mRNA, suggesting its degradation by nonsense-mediated mRNA decay. Expression of wild type and mutant IDS in COS-7 cells revealed that the IDS p.Gln310* mutant lacked IDS activity, consistent with production of a nonfunctional, prematurely truncated protein. Taken together, these results indicate that the IDS c.928C>T (p.Gln310*) mutation is a severe disease-causing mutation for MPS II.

Genotype-phenotype correlation in 44 Czech, Slovak, Croatian and Serbian patients with mucopolysaccharidosis type II.

Mucopolysaccharidosis type II (Hunter syndrome, MPS II, OMIM 309900) is an X-linked lysosomal storage disorder caused by deficiency of iduronate-2-sulfatase (IDS). We analyzed clinical and laboratory data from 44 Slavic patients with this disease. In total, 21 Czech, 7 Slovak, 9 Croatian and 7 Serbian patients (43 M/1 F) were included in the study (median age 11.0 years, range 1.2-43 years). Birth prevalence ranged from 1:69,223 (Serbia) to 1:192,626 (Czech Rep.). In the majority of patients (71%), the disease manifested in infancy. Cognitive functions were normal in 10 patients. Four, six and 24 patients had mild, moderate, and severe developmental delay, respectively, typically subsequent to developmental regression (59%). Residual enzyme activity showed no predictive value, and estimation of glycosaminoglycans (GAGs) had only limited importance for prognosis. Mutation analysis performed in 36 families led to the identification of 12 novel mutations, eight of which were small deletions/insertions. Large deletions/rearrangements and all but one small deletion/insertion led to a severe phenotype. This genotype-phenotype correlation was also identified in six cases with recurrent missense mutations. Based on patient genotype, the severity of the disease may be predicted with high probability in approximately half of MPS II patients.

Perturbations in cell signaling elicit early cardiac defects in mucopolysaccharidosis type II

Morphogens release and activity can be negatively affected by an impaired glycosaminoglycans (GAGs) turnover and proteoglycans assembly in the extracellular matrix, leading to altered tissue morphogenesis. In this work, we show that loss of Iduronate-2-sulfatase (IDS) activity, affecting GAGs catabolism and responsible for a life-threatening valvulopathy in mucopolysaccharidosis type II (MPSII), triggers early Sonic Hedgehog (Shh) and Wnt/β-catenin signaling defects, leading to aberrant heart development and atrioventricular valve formation in a zebrafish model. In addition, we consistently found impaired Shh signaling activity and cardiac electrophysiological abnormalities in IDS knockout mice at postnatal stages before any evident massive GAGs accumulation. These results suggest that IDS activity substantially affect cardiac morphogenesis through impaired Shh signaling and document an unexplored role of the enzyme in the fine-tuning of cell signaling pathways.

Arylsulfatase K is the Lysosomal 2-Sulfoglucuronate Sulfatase.

The degradation of glycosaminoglycans (GAGs) involves a series of exolytic glycosidases and sulfatases that act sequentially on the nonreducing end of the polysaccharide chain. Enzymes have been cloned that catalyze all of the known linkages with the exception of the removal of the 2-O-sulfate group from 2-sulfoglucuronate, which is found in heparan sulfate and dermatan sulfate. Here, we show using synthetic disaccharide substrates that arylsulfatase K is the glucuronate-2-sulfatase. Arylsulfatase K acts selectively on 2-sulfoglucuronate and lacks activity against 2-sulfoiduronate, whereas iduronate-2-sulfatase (IDS) desulfates synthetic disaccharides containing 2-sulfoiduronate but not 2-sulfoglucuronate. As arylsulfatase K has all of the properties expected of a lysosomal enzyme, we conclude that arylsulfatase K is the long sought lysosomal glucuronate-2-sulfatase, which we designate GDS.

A Rapid Two-Step Iduronate-2-Sulfatatse Enzymatic Activity Assay for MPSII Pharmacokinetic Assessment.

Clinical studies involving enzyme replacement therapies (ERTs) have increasingly utilized enzymatic activity assays to monitor efficacy and biofunction of the drug; as a result, these assays have become an important part of pharmacokinetic (PK) and pharmacodynamic assessments in ERT trials. This paper presents a two-step enzymatic activity assay for iduronate-2-sulfatase (I2S) (EC 3.1.6.13) which we have optimized to fit in 1 day and to complete in less than 6h. The rapid assay presented here is a significant improvement over the original two-step method with run time of 24h which spanned 2 days. The resulting 1 day assay is efficient, robust, reproducible, and better suited for use in pharmacokinetic studies. The method was fully validated in accordance with regulatory agency guidelines so that it could be implemented in PK studies. Validation of the method required additional modifications to circumvent limitations surrounding the calculation of accuracy. This challenge was overcome by developing strategies to determine both the expected and the measured values of validation samples in activity units. Subsequently, the method was validated in accordance with the FDA guidance for the validation of quantitative ligand binding assays (LBAs). Results of method development and optimization with focus on evaluations aimed at reducing the total assay run time as well as a summary of method validation performance are presented in this publication.

Structural basis of Hunter syndrome and construction of a database of mutant iduronate 2-sulfatase

Structural basis of Hunter syndrome and construction of a database of mutant iduronate 2-sulfatase

Correction of central nervous system deficits in the mouse model of Hunter syndrome by recombinant iduronate 2-sulfatase crossing the blood-brain barrier

Correction of central nervous system deficits in the mouse model of Hunter syndrome by recombinant iduronate 2-sulfatase crossing the blood-brain barrier

Comparative study of idursulfase beta and idursulfase in vitro and in vivo

Hunter syndrome is an X-linked lysosomal storage disease caused by a deficiency in the enzyme iduronate-2-sulfatase (IDS), leading to the accumulation of glycosaminoglycans (GAGs). Two recombinant enzymes, idursulfase and idursulfase beta are currently available for enzyme replacement therapy for Hunter syndrome. These two enzymes exhibited some differences in various clinical parameters in a recent clinical trial. Regarding the similarities and differences of these enzymes, previous research has characterized their biochemical and physicochemical properties. We compared the in vitro and in vivo efficacy of the two enzymes on patient fibroblasts and mouse model. Two enzymes were taken up into the cell and degraded GAGs accumulated in fibroblasts. In vivo studies of two enzymes revealed similar organ distribution and decreased urinary GAGs excretion. Especially, idursulfase beta exhibited enhanced in vitro efficacy for the lower concentration of treatment, in vivo efficacy in the degradation of tissue GAGs and improvement of bones, and revealed lower anti-drug antibody formation. A biochemical analysis showed that both enzymes show largely a similar glycosylation pattern, but the several peaks were different and quantity of aggregates of idursulfase beta was lower.

Structural Basis of Mucopolysaccharidosis Type II and Construction of a Database of Mutant Iduronate 2-Sulfatases.

Mucopolysaccharidosis type II (MPS II, Hunter syndrome) is an X-linked genetic disorder caused by a deficiency of iduronate 2-sulfatase (IDS), and missense mutations comprising about 30% of the mutations responsible for MPS II result in heterogeneous phenotypes ranging from the severe to the attenuated form. To elucidate the basis of MPS II from the structural viewpoint, we built structural models of the wild type and mutant IDS proteins resulting from 131 missense mutations (phenotypes: 67 severe and 64 attenuated), and analyzed the influence of each amino acid substitution on the IDS structure by calculating the accessible surface area, the number of atoms affected and the root-mean-square distance. The results revealed that the amino acid substitutions causing MPS II were widely spread over the enzyme molecule and that the structural changes of the enzyme protein were generally larger in the severe group than in the attenuated one. Coloring of the atoms influenced by different amino acid substitutions at the same residue showed that the structural changes influenced the disease progression. Based on these data, we constructed a database of IDS mutations as to the structures of mutant IDS proteins.

Generation of human induced pluripotent stem cell (iPSC) line from an unaffected female carrier of Mucopolysaccharidosis type II (MPS II) disorder

Peripheral blood was collected from a 39-year-old unaffected female carrier of an X-linked recessive mutation of Iduronate 2-sulfatase gene (NM_000202.7(IDS):c.85C>T) causing MPS II (OMIM 309900). Peripheral blood mononuclear cells (PBMCs) were reprogrammed by lentiviral delivery of a self-silencing hOKSM polycistronic vector. The pluripotency of iPSC line was confirmed by the expression of pluripotency-associated markers and in vitro spontaneous differentiation towards the 3 germ layers. The iPSC showed normal karyotype. The line offers a good platform to study MPS II pathophysiology, for drug testing, early biomarker discovery and gene therapy studies.