Hunter Syndrome Research Articles

Genetic features of patients with MPS type IIIB: Description of five pathogenic gene variations

BackgroundThere are four distinct forms of Sanfilippo syndrome (MPS type III), each of which is an autosomal lysosomal storage disorder. These forms are caused by abnormalities in one of four lysosomal enzymes. This study aimed to identify possible genetic variants that contribute to Sanfilippo IIIB in 14 independent families in Southwest Iran. MethodsPatients were included if their clinical features and enzyme assay results were suggestive. The patients were subsequently subjected to Sanger Sequencing to screen for Sanfilippo-related genes. Additional investigations have been conducted using various computational analyses to determine the probable functional effects of diagnosed variants. ResultsFive distinct variations were identified in the NAGLU gene. This included two novel variants in two distinct families and three previously reported variants in 12 distinct families. All of these variations were recognized as pathogenic using the MutationTaster web server. In silico analysis showed that all detected variants affected protein structural stability; four destabilized protein structures, and the fifth variation had the opposite effect. ConclusionIn this study, two novel variations in the NAGLU gene were identified. The results of this study positively contribute to the mutation diversity of the NAGLU gene. To identify new disease biomarkers and therapeutic targets, precision medicine must precisely characterize and account for genetic variations. New harmful gene variants are valuable for updating gene databases concerning Sanfilippo disease variations and NGS gene panels. This may also improve genetic counselling for rapid risk examinations and disease surveillance.

Analysis of caregiver perspectives on patients with mucopolysaccharidosis II treated with pabinafusp alfa: results of qualitative interviews in Japan

BackgroundMucopolysaccharidosis type II (MPS II), or Hunter syndrome, is a rare X-linked metabolic disorder predominantly affecting males. Pabinafusp alfa, an iduronate-2-sulfatase enzyme designed to cross the blood-brain barrier, was approved in Japan in 2021 as the first enzyme replacement therapy targeting both the neuropathic and somatic signs and symptoms of MPS II. This study reports caregivers’ experiences of MPS II patients receiving pabinafusp alfa through qualitative interviews.MethodsSemi-structured, qualitative interviews were conducted with caregivers at seven clinical sites in Japan using a semi-structured moderation guide (Voice of the Caregiver guide). Thematic analysis was applied to the interview transcripts to identify symptoms and health-related quality of life impacts at baseline, changes during treatment, and overall treatment experience.ResultsSeven caregivers from 16 trial sites participated, representing seven children aged 8–18 years who had received pabinafusp alfa for 3.3–3.5 years at the time of the interviews. Data suggest a general trend toward improvement in multiple aspects, although not all caregivers observed discernible changes. Reported cognitive improvements included language skills, concentration, self-control, eye contact, mental clarity, concept understanding, following instructions, and expressing personal needs. Further changes were reported that included musculoskeletal improvements and such somatic changes as motor function, mobility, organ involvement, joint mobility, sleep patterns, and fatigue. Four caregivers reported improvements in family quality of life, five expressed treatment satisfaction, and all seven indicated a strong willingness to continue treatment of their children with pabinafusp alfa.ConclusionCaregivers’ perspectives in this study demonstrate treatment satisfaction and improvement in various aspects of quality of life following therapy with pabinafusp alfa. These findings enhance understanding of pabinafusp alfa’s potential benefits in treating MPS II and contribute to defining MPS II-specific outcome measures for future clinical trials.

Mucopolysaccharidosis (MPS IIIA) mice have increased lung compliance and airway resistance, decreased diaphragm strength, and no change in alveolar structure.

Mucopolysaccharidosis type IIIA (MPS IIIA) is characterized by neurological and skeletal pathologies caused by reduced activity of the lysosomal hydrolase, sulfamidase, and the subsequent primary accumulation of undegraded heparan sulfate (HS). Respiratory pathology is considered secondary in MPS IIIA and the mechanisms are not well understood. Changes in the amount, metabolism, and function of pulmonary surfactant, the substance that regulates alveolar interfacial surface tension and modulates lung compliance and elastance, have been reported in MPS IIIA mice. Here we investigated changes in lung function in 20-wk-old control and MPS IIIA mice with a closed and open thoracic cage, diaphragm contractile properties, and potential parenchymal remodeling. MPS IIIA mice had increased compliance and airway resistance and reduced tissue damping and elastance compared with control mice. The chest wall impacted lung function as observed by an increase in airway resistance and a decrease in peripheral energy dissipation in the open compared with the closed thoracic cage state in MPS IIIA mice. Diaphragm contractile forces showed a decrease in peak twitch force, maximum specific force, and the force-frequency relationship but no change in muscle fiber cross-sectional area in MPS IIIA mice compared with control mice. Design-based stereology did not reveal any parenchymal remodeling or destruction of alveolar septa in the MPS IIIA mouse lung. In conclusion, the increased storage of HS which leads to biochemical and biophysical changes in pulmonary surfactant also affects lung and diaphragm function, but has no impact on lung or diaphragm structure at this stage of the disease.NEW & NOTEWORTHY Heparan sulfate storage in the lungs of mucopolysaccharidosis type IIIA (MPS IIIA) mice leads to changes in lung function consistent with those of an obstructive lung disease and includes an increase in lung compliance and airway resistance and a decrease in tissue elastance. In addition, diaphragm muscle contractile strength is reduced, potentially further contributing to lung function impairment. However, no changes in parenchymal lung structure were observed in mice at 20 wk of age.

The Impact of Pabinafusp Alfa on the Disease Burden in Hunter's Syndrome: Patient-Reported Outcomes

AbstractSevere mucopolysaccharidosis type II (MPS-II) patients present with progressive mental impairment and reduced life expectancy. While current available treatment cannot cross the blood–brain barrier, the enzyme replacement therapy with pabinafusp alfa (a recombinant iduronate-2-sulfatase fused to an antihuman transferrin receptor antibody) was designed to penetrate it using transferrin receptor-mediated transcytosis. In this cross-sectional retrospective study, we aimed to report the impact of this new therapy using patient-reported outcomes. Data were collected using standardized questionnaire replied by patients or their caregivers (as proxies). Nine patients received intravenous administration of pabinafusp alfa for at least 104 weeks. All patient showed improvements in behavior (mainly aggressiveness), speech, motor ability, muscle strength, facial expression, breathing, and cognitive skills. Gait improvement was also found in 78% of participants. Caregivers also reported improvements in emotion demonstration as ability to smile, establish eye contact, and give hugs. Collectively, our results indicate a positive impact of pabinafusp alfa on quality of life of individuals with MPS-II and their relatives/caregivers. Future studies are warranted to elucidate the mechanisms underlying these beneficial effects.

Investigation on lysosomal accumulation by a quantitative analysis of 2D phase-maps in digital holography microscopy.

Lysosomes are the terminal end of catabolic pathways in the cell, as well as signaling centers performing important functions such as the recycling of macromolecules, organelles, and nutrient adaptation. The importance of lysosomes in human health is supported by the fact that the deficiency of most lysosomal genes causes monogenic diseases called as a group Lysosomal Storage Diseases (LSDs). A common phenotypic hallmark of LSDs is the expansion of the lysosomal compartment that can be detected by using conventional imaging methods based on immunofluorescence protocols or overexpression of tagged lysosomal proteins. These methods require the alteration of the cellular architecture (i.e., due to fixation methods), can alter the behavior of cells (i.e., by the overexpression of proteins), and require sample preparation and the accurate selection of compatible fluorescent markers in relation to the type of analysis, therefore limiting the possibility of characterizing cellular status with simplicity. Therefore, a quantitative and label-free methodology, such as Quantitative Phase Imaging through Digital Holographic (QPI-DH), for the microscopic imaging of lysosomes in health and disease conditions may represent an important advance to study and effectively diagnose the presence of lysosomal storage in human disease. Here we proof the effectiveness of the QPI-DH method in accomplishing the detection of the lysosomal compartment using mouse embryonic fibroblasts (MEFs) derived from a Mucopolysaccharidosis type III-A (MSP-IIIA) mouse model, and comparing them with wild-type (WT) MEFs. We found that it is possible to identify label-free biomarkers able to supply a first pre-screening of the two populations, thus showing that QPI-DH can be a suitable candidate to surpass fluorescent drawbacks in the detection of lysosomes dysfunction. An appropriate numerical procedure was developed for detecting and evaluate such cellular substructures from in vitro cells cultures. Results reported in this study are encouraging about the further development of the proposed QPI-DH approach for such type of investigations about LSDs.

Evidence of epigenetic landscape shifts in mucopolysaccharidosis IIIB and IVA

Lysosomal storage diseases (LSDs) are a group of monogenic diseases characterized by mutations in genes coding for proteins associated with the lysosomal function. Despite the monogenic nature, LSDs patients exhibit variable and heterogeneous clinical manifestations, prompting investigations into epigenetic factors underlying this phenotypic diversity. In this study, we focused on the potential role of epigenetic mechanisms in the pathogenesis of mucopolysaccharidosis IIIB (MPS IIIB) and mucopolysaccharidosis IVA (MPS IVA). We analyzed DNA methylation (5mC) and histone modifications (H3K14 acetylation and H3K9 trimethylation) in MPS IIIB and MPS IVA patients’ fibroblasts and healthy controls. The findings revealed that global DNA hypomethylation is present in cell lines for both diseases. At the same time, histone acetylation was increased in MPS IIIB and MPS IVA cells in a donor-dependent way, further indicating a shift towards relaxed open chromatin in these MPS. Finally, the constitutive heterochromatin marker, histone H3K9 trimethylation, only showed reduced clustering in MPS IIIB cells, suggesting limited alterations in heterochromatin organization. These findings collectively emphasize the significance of epigenetic mechanisms in modulating the phenotypic variations observed in LSDs. While global DNA hypomethylation could contribute to the MPS pathogenesis, the study also highlights individual-specific epigenetic responses that might contribute to phenotypic heterogeneity. Further research into the specific genes and pathways affected by these epigenetic changes could provide insights into potential therapeutic interventions for these MPS and other LSDs.

An empowered, clinically viable hematopoietic stem cell gene therapy for the treatment of multisystemic mucopolysaccharidosis type II

Mucopolysaccharidosis type II (MPS II), or Hunter syndrome, is a rare X-linked recessive lysosomal storage disorder due to a mutation in the lysosomal enzyme iduronate-2-sulfatase (IDS) gene. IDS deficiency leads to a progressive, multisystem accumulation of glycosaminoglycans (GAGs) and results in central nervous system (CNS) manifestations in the severe form. We developed up to clinical readiness a new hematopoietic stem cell (HSC) gene therapy approach for MPS II that benefits from a novel highly effective transduction protocol. We first provided proof of concept of efficacy of our approach aimed at enhanced IDS enzyme delivery to the CNS in a murine study of immediate translational value, employing a lentiviral vector (LV) encoding a codon-optimized human IDS cDNA. Then the therapeutic LV was tested for its ability to efficiently and safely transduce bona fide human HSCs in clinically relevant conditions according to a standard vs. a novel protocol that demonstrated superior ability to transduce bona fide long-term repopulating HSCs. Overall, these results provide strong proof of concept for the clinical translation of this approach for the treatment of Hunter syndrome.

Abstract WP228: Vertebral Artery Configuration as a Risk Factor for Dissection in Children

Introduction: Arterial ischemic strokes are estimated to occur in 1.2 to 8 per 100,000 children per year with 15-22% occurring in the posterior circulation. Vertebral artery dissection(VAD) is a known cause of posterior circulation ischemic stroke in approx 7% of cases. Pediatric Bow Hunter syndrome, usually presents distinctively with VAD and stroke. It most commonly involves the V3 segment. In 2021, Braga et all proposed a new protocol for management for children with spontaneous VAD.They noted 2 different configurations of the vertebral artery. In this study we go on the explore these different configurations further and their role in spontaneous VAD. Aim & Hypothesis: Two configurations of the vertebral artery at the V3 segment were observed. Type A and Type B depending on the angle of curvature of the V3 segment. Type A config. is more linear with > 110 degree of angulation. Type B config. is angulated with 2 < 110 degree angles. We aim to investigate these configurations in patients without dissection vs those with vertebral artery dissection. We hypothesized that Type B configuration would be more prevalent in patients with spontaneous VAD. Methods: Retrospective chart review conducted at UTSW medical center. MRA/IR angiograms reviewed of 49 patients; 19 with spontaneous VAD and 30 with no vertebral pathology. Results: 79% of the total dissected vessels(19/24) had configuration Type B and 20.83%(5/24) had configuration Type A. In the control group of 30 patients with no VAD, TypeB was present in 25.4%(13/51) and configuration A in 74.5% (38/51). Type B configuration had a statistically significant higher prevalence in V3 dissection group. (p=<0.001) Conclusion: Type B configuration of the V3 segment would warrant further investigation in the right setting.

A phase I/II clinical trial of JR-441 for treatment of Sanfilippo syndrome type A (MPS IIIA)

A phase I/II clinical trial of JR-441 for treatment of Sanfilippo syndrome type A (MPS IIIA)

Superior outcomes in neuroretina following IV versus intra-CSF AAV9 gene replacement in mice with MPS IIIA

Superior outcomes in neuroretina following IV versus intra-CSF AAV9 gene replacement in mice with MPS IIIA

Impact of anakinra on disordered movement in Sanfilippo syndrome

Impact of anakinra on disordered movement in Sanfilippo syndrome

A phase III clinical trial of GC1111 as an enzyme replacement therapy in previously untreated mucopolysaccharidosis type II (Hunter syndrome) patients: A double-blind, randomized, active-controlled (part 1) and open-labeled, historical placebo-controlled (part 2) study

A phase III clinical trial of GC1111 as an enzyme replacement therapy in previously untreated mucopolysaccharidosis type II (Hunter syndrome) patients: A double-blind, randomized, active-controlled (part 1) and open-labeled, historical placebo-controlled (part 2) study

Clinical outcomes and sustained biochemical engraftment following ex-vivo autologous stem cell gene therapy for mucopolysaccharidosis type IIIA

Clinical outcomes and sustained biochemical engraftment following ex-vivo autologous stem cell gene therapy for mucopolysaccharidosis type IIIA

ETV:SGSH, a brain-penetrant enzyme transport vehicle for SGSH, improves lysosomal and microglial morphology, degeneration and cognitive behavior in MPS IIIA mice

ETV:SGSH, a brain-penetrant enzyme transport vehicle for SGSH, improves lysosomal and microglial morphology, degeneration and cognitive behavior in MPS IIIA mice

Therapeutic potential of intracerebroventricular recombinant human heparan-N-sulfatase enzyme replacement therapy in MPS IIIA mice

Therapeutic potential of intracerebroventricular recombinant human heparan-N-sulfatase enzyme replacement therapy in MPS IIIA mice

Systemic inflammation leads to neuronal loss and exacerbates behavioural deficits in a mouse model of MPS IIIA

Systemic inflammation leads to neuronal loss and exacerbates behavioural deficits in a mouse model of MPS IIIA

Elucidation of the pathogenesis of heparan sulfate in MPS IIIB mice using a membrane-tethered form of NAGLU

Elucidation of the pathogenesis of heparan sulfate in MPS IIIB mice using a membrane-tethered form of NAGLU

New blood-based biomarkers for Sanfilippo syndrome

New blood-based biomarkers for Sanfilippo syndrome

Molecular mechanism of resveratrol-induced autophagy in mouse model of Sanfilippo syndrome type IIIB

Molecular mechanism of resveratrol-induced autophagy in mouse model of Sanfilippo syndrome type IIIB

Structural Parameters of the Brain and Bone Structures of the Head and Neck in Patients with Various Types of Mucopolysaccharidoses According to Magnetic Resonance Imaging of the Brain

Background. Mucopolysaccharidoses are diseases from the group of lysosomal storage diseases that have a progressive course. CNS damage is one of the main factors in the development of severe, life-threatening complications. Aims — аssessment of structural changes in the brain and bones of the head and neck in patients with various types of mucopolysaccharidoses. Methods. The research included 136 children aged from 11 months to 17 years, 81 patients of which showed various types of mucopolysaccharidoses: MPS I — 15 people, MPS II — 37, MPS III A — 10, MPS IIIB — 4, MPS IIIC — 2, MPS IVA — 6, VI — 7 people. The control group included 56 children without neurological, psychiatric and severe somatic illnesses. Results. For mucopolysaccharidoses types I, II, III and VI, the most characteristic structural changes on the brain MRI were white matter lesions, mainly periventricular: expansion of the perivascular spaces (70%), atrophy of the cerebral hemispheres (42%), hippocampus, (31%), ventriculomegaly (6.2%), stenosis of the cervical spine (64%), hydrocephalus, expansion of the cerebrospinal fluid spaces of the posterior cranial fossa, arachnoid cysts. Conclusions. The results of the obtained data analysis made it possible to identify the macrostructural specifics of the brain disorders and cervical spine in various types of MPS, as well as their prognostic significance.