Efficacy of Enzyme Replacement Therapy on the range of motion of the upper and lower extremities in 16 Polish patients with mucopolysaccharidosis type II: A long-term follow-up study.

BACKGROUND: Enzyme replacement therapy (ERT) with idursulfase is available for patients with mucopolysaccharidosis (MPS) type II, and improvements in certain somatic signs and symptoms have been reported. The aim of the study was to assess the effectiveness of ERT with idursulfase (Elaprase®) on the passive joint range of motion (JROM) in the upper and lower extremities of patients with MPS II. METHODS: The study included 16 Polish patients diagnosed with MPS II and followed in our Institute in the years 2009-2016. The study group was divided for groups of neuronopathic (group 1, n=12) and non-neuronopathic (group 2, n=4) patients. A passive JROM was measured with a goniometer by one physiotherapist, while in group 1 it was assessed at baseline and after both short-term (52 weeks) and long-term (mean 230 weeks, range: 108-332 weeks) ERT. In group 2, it was assessed at baseline and after short-term ERT (68-85 weeks, no data for long-term ERT). RESULTS: In group 1, after 52 weeks of ERT, we observed some improvement of passive ROM in wrist flexion (5/12 patients), shoulder abduction and wrist extension (3/12 patients), shoulder flexion, elbow and knee extension (2/12 patients). After long-term ERT (mean 230 weeks), the improvement in JROM was observed only in 2 patients. There was no improvement in the shoulder abduction, elbow flexion and extension, hip and knee extension. In group 2, the improvement in passive ROM was observed in several joints: shoulder flexion, wrist flexion and extension improved (2/4 patients) and shoulder abduction (1/4 patients). CONCLUSION: ERT is of low efficacy on correcting the range of motion of joints in MPS II patients.

Iduronate-2-sulfatase transport vehicle rescues behavioral and skeletal phenotypes in a mouse model of Hunter syndrome.

Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disorder caused by deficiency of the iduronate-2-sulfatase (IDS) enzyme, resulting in cellular accumulation of glycosaminoglycans (GAGs) throughout the body. Treatment of MPS II remains a considerable challenge as current enzyme replacement therapies do not adequately control many aspects of the disease, including skeletal and neurological manifestations. We developed an IDS transport vehicle (ETV:IDS) that is engineered to bind to the transferrin receptor; this design facilitates receptor-mediated transcytosis of IDS across the blood-brain barrier and improves its distribution into the brain while maintaining distribution to peripheral tissues. Here we show that chronic systemic administration of ETV:IDS in a mouse model of MPS II reduced levels of peripheral and central nervous system GAGs, microgliosis, and neurofilament light chain, a biomarker of neuronal injury. Additionally, ETV:IDS rescued auricular and skeletal abnormalities when introduced in adult MPS II mice. These effects were accompanied by improvements in several neurobehavioral domains, including motor skills, sensorimotor gating, and learning and memory. Together, these results highlight the therapeutic potential of ETV:IDS for treating peripheral and central abnormalities in MPS II. DNL310, an investigational ETV:IDS molecule, is currently in clinical trials as a potential treatment for patients with MPS II.

Can serial cerebral MRIs predict the neuronopathic phenotype of MPS II?

OBJECTIVE: To advance the prediction of the neurocognitive development in MPS II patients by jointly analyzing MRI and neurocognitive data in mucopolysaccharidosis (MPS) II patients. METHODS: Cognitive ability scores (CAS) were obtained by neuropsychological testing. Cerebral MRIs were quantified using a disease-specific protocol. MRI sumscores were calculated for atrophy, white-matter abnormalities (WMA) and Virchow-Robin spaces (VRS). To distinguish between atrophy and hydrocephalus the Evans' index and the callosal angle (CA) were measured. A random effects repeated measurement model was used to correlate CAS with the three MRI sumscores. RESULTS: MRI (n = 47) and CAS scores (n = 78) of 19 male patients were analyzed. Ten patients were classified as neuronopathic and nine as non-neuronopathic. Neuronopathic patients had normal cognitive development until age 3 years. Mental age plateaued between ages 3 and 6, and subsequently declined with loss of skills at a maximum developmental age of 4 years. MRIs of neuronopathic patients showed abnormal atrophy sumscores before CAS dropped below the threshold for intellectual disability (<70). White-matter abnormalities (WMA) and brain atrophy progressed. The calculated sumscores were inversely correlated with CAS (r = -.90 for atrophy and -.69 for WMA). This was not biased by the influence of hydrocephalus as shown by measurement of the Evans' and callosal angle. Changes over time in the Virchow-Robin spaces (VRS) on MRI were minimal. CONCLUSION: In our cohort, brain atrophy showed a stronger correlation to a decline in CAS when compared to WMA. Atrophy-scores were higher in young neuronopathic patients than in non-neuronopathic patients and atrophy was an important early sign for the development of the neuronopathic phenotype, especially when observed jointly with white-matter abnormalities.

Applying the functional independence measure to the assessment of patients with mucopolysaccharidosis / Test de medida de independencia funcional en la evaluación de pacientes con mucopolisacaridosis

Abstract Objective: To assess the functional independence of a group of patients with mucopolysaccharidosis using the Functional Independence Measure as a tool that accomplishes this purpose. Methods: This is a cross-sectional study of patients with mucopolysaccharidosis. Our data was collected between June 2015 and July 2016. In addition to history of present illness and physical examination each study participant was asked to answer a questionnaire to specifically evaluate their functional independence using the functional independence measure. the internal consistency of the functional independence measure was assessed using Cronbach's alpha coefficient. Results: We collected data on 20 patients with mucopolysaccharidosis. The average age was 10.8 (8.67-13.03) years, the average weight was 23.6 (19.91-27.37) kg and the average height was 1 (0.83-1.17) m. The most prevalent type of mucopolysaccharidosis in the study was type VI (n= 14). The average total functional independence measure score was 104.4 (97.61-111.19), the average for the mobility domain was 73.50 (68.22-78.78) and the average for the cognitive function domain was 30.90 (28.68-33.13). The internal consistency of the entire questionnaire was 0.859, with values of 0.966 for the mobility domain and 0.624 for the cognitive function domain. Conclusion: The lowest functional independence measure scores were obtained in the following sub-domains: self-care, locomotion and cognitive function. The functional independence measure questionnaire demonstrated internal consistency for the evaluation of functional independence in patients with mucopolysaccharidosis, being able to value all the affected sub-domains separately.

Resumen Objetivo: Evaluar la independencia funcional de un grupo de pacientes con mucopolisacaridosis utilizando la Medida de Independencia Funcional como herramienta para lograr este propósito. Métodos: Este es un estudio transversal de pacientes con mucopolisacaridosis. Nuestros datos se recopilaron entre junio de 2015 y julio de 2016. Además de la historia de la enfermedad actual y el examen físico, se pidió a cada participante del estudio que respondiera un cuestionario para evaluar específicamente su independencia funcional utilizando la Medida de Independencia Funcional. la consistencia interna de la Medida de Independencia Funcional se evaluó mediante el coeficiente alfa de Cronbach. Resultados: Recopilamos datos de 20 pacientes con mucopolisacaridosis. La edad promedio fue de 10.8 (8.67-13.03) años, el peso promedio fue de 23.6 (19.91-27.37) kg y la altura promedio fue de 1 m (0.83-1.17). El tipo de mucopolisacaridosis más prevalente en el estudio fue el tipo VI (n= 14). El puntaje promedio de la medida de independencia funcional total fue 104.4 (97.61-111.19), el promedio para el dominio de movilidad fue 73.50 (68.22-78.78) y el promedio para el dominio de función cognitiva fue 30.90 (28.68-33.13). La consistencia interna de todo el cuestionario fue de 0.859, con valores de 0.966 para el dominio de movilidad y 0.624 para el dominio de función cognitiva. Conclusión: Las puntuaciones más bajas de la medida de independencia funcional se obtuvieron en los siguientes subdominios: autocuidado, locomoción y función cognitiva. El cuestionario de medida de independencia funcional demostró consistencia interna para la evaluación de la independencia funcional en pacientes con mucopolisacaridosis, pudiendo valorar todos los subdominios afectados por separado.

Case report of endoprosthesis -Y implantation in severe respiratory failure in the MPSII patient; comparison with literature data.

BACKGROUND: The tracheobronchomalacia is a life-threatening complication of mucopolysaccharidosis (MPS) without known effective, optimal treatment. The severe expiratory collapse of the trachea and bronchi is one of causes of the high rate of deaths in the course of airway impairment in MPSII patients. CASE PRESENTATION: Due to the adynamic tracheobronchomalacia despite of enzymatic treatment (ERT) in our MPSII patient, a life-saving tracheal bifurcated type-Y endoprosthesis (a self-expanding, metal stent for the prosthesis of tracheal and bronchial stenosis) was implanted. In the followed months, the breathing efficiency improved, but then gradual worsening, progression of bronchi occlusion at the stent border resulted in patient's death. CONCLUSION: The Y-stent implantation appears to be a short-term, life-saving solution without satisfactory long-term effects due to the progress of peripheral bronchomalacia and increased tissue proliferation and granulation, that arises during the illness' course.

Applying the functional independence measure to the assessment of patients with mucopolysaccharidosis.

OBJECTIVE: To assess the functional independence of a group of patients with mucopolysaccharidosis using the Functional Independence Measure as a tool that accomplishes this purpose. METHODS: This is a cross-sectional study of patients with mucopolysaccharidosis. Our data was collected between June 2015 and July 2016. In addition to history of present illness and physical examination each study participant was asked to answer a questionnaire to specifically evaluate their functional independence using the functional independence measure. the internal consistency of the functional independence measure was assessed using Cronbach's alpha coefficient. RESULTS: We collected data on 20 patients with mucopolysaccharidosis. The average age was 10.8 (8.67-13.03) years, the average weight was 23.6 (19.91-27.37) kg and the average height was 1 (0.83-1.17) m. The most prevalent type of mucopolysaccharidosis in the study was type VI (n= 14). The average total functional independence measure score was 104.4 (97.61-111.19), the average for the mobility domain was 73.50 (68.22-78.78) and the average for the cognitive function domain was 30.90 (28.68-33.13). The internal consistency of the entire questionnaire was 0.859, with values of 0.966 for the mobility domain and 0.624 for the cognitive function domain. CONCLUSION: The lowest functional independence measure scores were obtained in the following sub-domains: self-care, locomotion and cognitive function. The functional independence measure questionnaire demonstrated internal consistency for the evaluation of functional independence in patients with mucopolysaccharidosis, being able to value all the affected sub-domains separately.

OBJETIVO: Evaluar la independencia funcional de un grupo de pacientes con mucopolisacaridosis utilizando la Medida de Independencia Funcional como herramienta para lograr este propósito. MÉTODOS: Este es un estudio transversal de pacientes con mucopolisacaridosis. Nuestros datos se recopilaron entre junio de 2015 y julio de 2016. Además de la historia de la enfermedad actual y el examen físico, se pidió a cada participante del estudio que respondiera un cuestionario para evaluar específicamente su independencia funcional utilizando la Medida de Independencia Funcional. la consistencia interna de la Medida de Independencia Funcional se evaluó mediante el coeficiente alfa de Cronbach. RESULTADOS: Recopilamos datos de 20 pacientes con mucopolisacaridosis. La edad promedio fue de 10.8 (8.67-13.03) años, el peso promedio fue de 23.6 (19.91-27.37) kg y la altura promedio fue de 1 m (0.83-1.17). El tipo de mucopolisacaridosis más prevalente en el estudio fue el tipo VI (n= 14). El puntaje promedio de la medida de independencia funcional total fue 104.4 (97.61-111.19), el promedio para el dominio de movilidad fue 73.50 (68.22-78.78) y el promedio para el dominio de función cognitiva fue 30.90 (28.68-33.13). La consistencia interna de todo el cuestionario fue de 0.859, con valores de 0.966 para el dominio de movilidad y 0.624 para el dominio de función cognitiva. CONCLUSIÓN: Las puntuaciones más bajas de la medida de independencia funcional se obtuvieron en los siguientes subdominios: autocuidado, locomoción y función cognitiva. El cuestionario de medida de independencia funcional demostró consistencia interna para la evaluación de la independencia funcional en pacientes con mucopolisacaridosis, pudiendo valorar todos los subdominios afectados por separado.

Significance of Provocative Perfusion Computed Tomography for Evaluation of Bow Hunter Syndrome.

Bow hunter syndrome (BHS) is a rare vascular phenomenon of vertebrobasilar insufficiency caused by dynamic stenosis of the vertebral artery (VA) by osteophytes, fibrous bands, or disk herniation with neck rotation. We present a rare case of a patient with bilaterally patent VAs on neutral imaging and bilateral dynamic compression of VA with left head rotation. Provocation tests are critical toward understanding dynamic pathophysiology of BHS because normal neutral vascular imaging does not preclude diagnosis of BHS. Although dynamic angiography is the gold standard for diagnosis of BHS, cerebral angiography could be invasive and risky. Provocative test using perfusion computed tomography scan is a simple and noninvasive method to assess BHS on an outpatient basis.

Validation of the shortened Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale (HS-FOCUS).

BACKGROUND: The rare disease, Hunter Syndrome (mucopolysaccharidosis type II; MPS II), characterized by iduronate-2-sulfatase deficiency, has heterogeneous symptoms often including cognitive impairment (CI). To evaluate physical functioning and daily activity limitations of patients with MPS II, the multidomain shortened Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale (HS-FOCUS) questionnaire was previously developed and preliminarily validated. Here we gather data in a dedicated prospective longitudinal observational study using direct responses to the shortened instrument and assess its psychometric properties further. METHODS: Interview data were collected from eligible self-reporting patients (≥ 12 years of age) or caregivers of patients using respective versions of the instrument at baseline and 2-4 weeks later. Internal consistency, test-retest reliability, convergent and discriminant validity, and validity of known groups were assessed. Participants also completed Child Health Questionnaire (CHQ), Health Utilities Index Mark 3, and Global Impression of Severity (GIS) questionnaires. RESULTS: All patients were male, consisting of 31 caregiver-reported patients (aged 3-26 years) and 20 self-reported patients (aged 12-58 years). Most (77.4%) caregiver-reported patients had CI. Both questionnaire versions demonstrated good internal consistency and test-retest reliability; Cronbach's alpha and intra-class correlation coefficients were > 0.70. Spearman's correlations demonstrated good convergent validity with moderate (> 0.3) to high (> 0.6) correlations of the HS-FOCUS total score with physical functioning, role/social-physical, and bodily pain domains of CHQ. The tool also differentiated between MPS II severity levels based on GIS scores. CONCLUSIONS: The shortened HS-FOCUS questionnaire was found to be a valid and reliable tool to assess the physical functioning impact of MPS II.

Dose-Dependent Prevention of Metabolic and Neurologic Disease in Murine MPS II by ZFN-Mediated In Vivo Genome Editing.

Mucopolysaccharidosis type II (MPS II) is an X-linked recessive lysosomal disorder caused by deficiency of iduronate 2-sulfatase (IDS), leading to accumulation of glycosaminoglycans (GAGs) in tissues of affected individuals, progressive disease, and shortened lifespan. Currently available enzyme replacement therapy (ERT) requires lifelong infusions and does not provide neurologic benefit. We utilized a zinc finger nuclease (ZFN)-targeting system to mediate genome editing for insertion of the human IDS (hIDS) coding sequence into a "safe harbor" site, intron 1 of the albumin locus in hepatocytes of an MPS II mouse model. Three dose levels of recombinant AAV2/8 vectors encoding a pair of ZFNs and a hIDS cDNA donor were administered systemically in MPS II mice. Supraphysiological, vector dose-dependent levels of IDS enzyme were observed in the circulation and peripheral organs of ZFN+donor-treated mice. GAG contents were markedly reduced in tissues from all ZFN+donor-treated groups. Surprisingly, we also demonstrate that ZFN-mediated genome editing prevented the development of neurocognitive deficit in young MPS II mice (6-9 weeks old) treated at high vector dose levels. We conclude that this ZFN-based platform for expression of therapeutic proteins from the albumin locus is a promising approach for treatment of MPS II and other lysosomal diseases.

Multimodal image analysis of the retina in Hunter syndrome (mucopolysaccharidosis type II): Case report.

INTRODUCTION: We report a case of retinal and posterior ocular findings in a 33-year-old man diagnosed with Hunter syndrome (Mucopolysaccharidosis type II) in a multimodal imaging way. CASE PRESENTATION: Our patient was complaining of blurred night vision for the past 3 years. He had not received any systemic treatment for Hunter syndrome. Vision acuity was 20/20 in both eyes and corneas were clear. Fundus examination revealed bilateral crowded and hyperemic optic nerve heads (elevated in the ocular ultrasound) and areas of subretinal hypopigmentation. There was hyperautofluorescence at the central fovea and perifovea, and a diffuse bilateral choroidal fluorescence in angiography. Macular SD-OCT showed a thinning of the external retina at the perifovea in both eyes. Visual field testing showed a bilateral ring scotoma. The full field ERG was subnormal, with a negative response in the scotopic phase. Visual Evoked Potencial test and cranial MRI were normal. CONCLUSION: Our multimodal analysis reported here attempted to contribute to the knowledge of the natural history of GAG deposition in the eye, focusing on the retina and retinal pigment epithelium. Defining this natural history is essential for a proper comparison with Hunter patients receiving systemic treatment, thus determining if it can or cannot improve retinal function in humans with this disorder.

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.

Treatment of mucopolysaccharidosis type II (Hunter syndrome): results from a systematic evidence review.

PurposeA pilot systematic evidence review to establish methodology utility in rare genetic diseases, support clinical recommendations, and identify important knowledge gaps.MethodsBroad-based published/gray-literature searches through December 2015 for studies of males with confirmed mucopolysaccharidosis type II (any age, phenotype, genotype, family history) treated with enzyme replacement therapy or hematopoietic stem cell transplantation. Preset inclusion criteria employed for abstract and full document selection, and standardized methods for data extraction and assessment of quality and strength of evidence.ResultsTwelve outcomes reported included benefits of urinary glycosaminoglycan and liver/spleen volume reductions and harms of immunoglobulin G/neutralizing antibody development (moderate strength of evidence). Less clear were benefits of improved 6-minute walk tests, height, early treatment, and harms of other adverse reactions (low strength of evidence). Benefits and harms of other outcomes were unclear (insufficient strength of evidence). Current benefits and harms of hematopoietic stem cell transplantation are unclear, based on dated, low-quality studies. A critical knowledge gap is long-term outcomes. Consensus on selection of critical outcomes and measures is needed to definitively evaluate treatment safety and effectiveness.ConclusionMinor methodology modifications and a focus on critical evidence can reduce review time and resources. Summarized evidence was sufficient to support guidance development and highlight important knowledge gaps.

Cognitive endpoints for therapy development for neuronopathic mucopolysaccharidoses: Results of a consensus procedure.

The design and conduct of clinical studies to evaluate the effects of novel therapies on central nervous system manifestations in children with neuronopathic mucopolysaccharidoses is challenging. Owing to the rarity of these disorders, multinational studies are often needed to recruit enough patients to provide meaningful data and statistical power. This can make the consistent collection of reliable data across study sites difficult. To address these challenges, an International MPS Consensus Conference for Cognitive Endpoints was convened to discuss approaches for evaluating cognitive and adaptive function in patients with mucopolysaccharidoses. The goal was to develop a consensus on best practice for the design and conduct of clinical studies investigating novel therapies for these conditions, with particular focus on the most appropriate outcome measures for cognitive function and adaptive behavior. The outcomes from the consensus panel discussion are reported here.

Identification of age-dependent motor and neuropsychological behavioural abnormalities in a mouse model of Mucopolysaccharidosis Type II.

Severe mucopolysaccharidosis type II (MPS II) is a progressive lysosomal storage disease caused by mutations in the IDS gene, leading to a deficiency in the iduronate-2-sulfatase enzyme that is involved in heparan sulphate and dermatan sulphate catabolism. In constitutive form, MPS II is a multi-system disease characterised by progressive neurocognitive decline, severe skeletal abnormalities and hepatosplenomegaly. Although enzyme replacement therapy has been approved for treatment of peripheral organs, no therapy effectively treats the cognitive symptoms of the disease and novel therapies are in development to remediate this. Therapeutic efficacy and subsequent validation can be assessed using a variety of outcome measures that are translatable to clinical practice, such as behavioural measures. We sought to consolidate current knowledge of the cognitive, skeletal and motor abnormalities present in the MPS II mouse model by performing time course behavioural examinations of working memory, anxiety, activity levels, sociability and coordination and balance, up to 8 months of age. Cognitive decline associated with alterations in spatial working memory is detectable at 8 months of age in MPS II mice using spontaneous alternation, together with an altered response to novel environments and anxiolytic behaviour in the open-field. Coordination and balance on the accelerating rotarod were also significantly worse at 8 months, and may be associated with skeletal changes seen in MPS II mice. We demonstrate that the progressive nature of MPS II disease is also seen in the mouse model, and that cognitive and motor differences are detectable at 8 months of age using spontaneous alternation, the accelerating rotarod and the open-field tests. This study establishes neurological, motor and skeletal measures for use in pre-clinical studies to develop therapeutic approaches in MPS II.

Association between brain structural anomalies, electroencephalogram and history of seizures in Mucopolysaccharidosis type II (Hunter syndrome).

Mucopolysaccharidosis type II or Hunter syndrome (MPS II) is a genetic disease that can course with intellectual impairment and central nervous system (CNS) alterations. To date, no report has documented electroencephalogram (EEG) measures associated with CNS alterations, detected by imaging studies, and the history of seizures in patients with MPS II. Therefore, we decided to search this association. We included 9 patients with MPS II and performed imaging studies of the brain to detect the presence of cortico-subcortical atrophy, enlarged subarachnoid space and supratentorial ventricular size. Additionally, we performed EEG studies in sleep and awake conditions and a complete clinical description. Five out of the nine patients presented history of seizures and all except one patient (88.9%) presented some CNS structural alteration in the imaging studies, being the most frequent the cortico-subcortical atrophy (77.8%). The EEG results showed low amplitude in all patients and low voltage in sleep condition in eight patients with interhemispheric asymmetry in six patients during awake and sleep conditions. Although the five patients with history of seizures did not present a distinctive EEG anomaly, four of them presented some structural alteration in the imaging studies. In conclusion, most patients presented structural alterations in the CNS; likewise, all of them presented EEG anomalies mainly during sleep conditions. However, a clear association between EEG, CNS and the history of seizures was not established.

Delivery of an Adeno-Associated Virus Vector into Cerebrospinal Fluid Attenuates Central Nervous System Disease in Mucopolysaccharidosis Type II Mice.

Mucopolysaccharidosis type II (MPS II) is a rare X-linked genetic disorder caused by deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS), leading to impaired catabolism of ubiquitous polysaccharides and abnormal accumulation of these undegraded substrates in the lysosome. Like many lysosomal storage diseases, MPS II is characterized by both somatic and central nervous system (CNS) involvement. Intravenous enzyme replacement therapy can improve somatic manifestations of MPS II, but systemic IDS does not cross the blood-brain barrier and therefore cannot address CNS disease. In this study, an adeno-associated virus serotype 9 vector carrying the IDS gene was injected into the cerebrospinal fluid (CSF) of IDS deficient mice, a model of MPS II. Treated mice exhibited dose-dependent IDS expression and resolution of brain storage lesions, as well as improvement in long-term memory in a novel object recognition test. These findings suggest that delivery of adeno-associated virus vectors into CSF could serve as a platform for efficient, long-term enzyme delivery to the CNS, potentially addressing this critical unmet need for patients with MPS II and many related lysosomal enzyme deficiencies.

Identification and characterization of 20 novel pathogenic variants in 60 unrelated Indian patients with mucopolysaccharidoses type I and type II.

Mucopolysaccharidoses (MPS), a subgroup of lysosomal storage disorders, are caused due to deficiency of specific lysosomal enzyme involved in catabolism of glycosaminoglycans. To date more than 200 pathogenic variants in the alpha-l-iduronidase (IDUA) for MPS I and ∼500 pathogenic variants in the iduronate-2-sulphatase (IDS) for MPS II have been reported worldwide. The mutation spectrum of MPS type I and MPS type II disorders in Indian population is not characterized yet. In this study, we carried out clinical, biochemical, molecular and in silico analyses to establish the mutation spectrum of MPS I and MPS II in the Indian population. We conducted molecular analysis for 60 MPS-affected patients [MPS I (n = 30) (Hurler syndrome = 17, Hurler-Scheie syndrome = 13), and MPS II (n = 30) (severe = 18, attenuated = 12)] and identified a total of 44 [MPS I (n = 22) and MPS II (n = 22)] different pathogenic variants comprising missense, nonsense, frameshift, gross deletions and splice site variants. A total of 20 [MPS I (n = 14), and MPS II (n = 6)] novel pathogenic sequence variants were identified in our patient cohort. We found that 32% of pathogenic variants detected in IDUA were recurrent and 25% in MPS II. This is the first study revealing the mutation spectrum of MPS I and MPS II patients in the Indian population.

Severe tracheal and bronchial collapse in adults with type II mucopolysaccharidosis.

BACKGROUND: Mucopolysaccharidosis type II (MPSII) patients frequently suffer from dyspnoea caused by restrictive airway disease due to skeletal abnormalities as well as glycosaminoglycans (GAG) accumulation at different levels of the airway, including the trachea. In this study we describe the extent of the tracheal and bronchial narrowing, the changes in airway diameter during respiration and the effects of these obstructions on respiratory function in adult MPSII patients. METHODS: Five adult MPSII patients (mean age 40 years) were included. Pulmonary function tests and in- and expiratory chest CT scans were obtained. Cross-sectional areas of trachea and main bronchi were measured at end-inspiration and -expiration and percentage collapse was calculated. RESULTS: There was diffuse narrowing of the entire intra-thoracic trachea and main bronchi and severe expiratory collapse of the trachea in all patients. At 1 cm above the aortic arch the median % collapse of the trachea was 68 (range 60 to 77%), at the level of the aortic arch 64 (range 21-93%), for the main bronchi this was 58 (range 26-66%) on the left and 44 (range 9-76%) on the right side. The pulmonary function tests showed that this airway collapse results in obstructive airway disease in all patients, which was severe (forced expiratory volume <50% of predicted) in four out of five patients. CONCLUSION: In adult MPS II patients, central airways diameters are strikingly reduced and upon expiration there is extensive collapse of the trachea and main bronchi. This central airways obstruction explains the severe respiratory symptoms in MPSII patients.