[Importance of lysosomal storage diseases in rheumatology]. / Bedeutung lysosomaler Speicherkrankheiten in der Rheumatologie.

Lysosomal storage diseases are a group of rare hereditary metabolic diseases. Due to a deficiency of lysosomal enzymes, complex substrates accumulate in the lysosomes of various organs. Depending on the affected enzyme, this results in clinically variable and chronic progressive multiorgan diseases. Diagnosis is often delayed. As clinical symptoms include the musculoskeletal system, an awareness of lysosomal storage diseases is of relevance to (pediatric) rheumatologists. This article is focused on Mucopolysaccharidosis type I­S, Mucolipidosis type III, Gaucher disease and Fabry disease. When suspecting a lysosomal storage disease, enzyme activity should be determined in dried blood spots or leukocytes. For some diseases, specific biomarkers can additionally be analyzed. Diagnosis should be confirmed by genetic testing. As causal treatment options are available for three of the presented diseases, a timely diagnosis is very important.

A retrospective study of morbidity and mortality of chronic acid sphingomyelinase deficiency in Germany.

BACKGROUND: Acid sphingomyelinase deficiency (ASMD) is a rare, progressive, potentially fatal lysosomal storage disease that exhibits a broad spectrum of clinical phenotypes. There is a need to expand the knowledge of disease mortality and morbidity in Germany because of limited information on survival analysis in patients with chronic ASMD (type B or type A/B). METHODS: This observational, multicentre, retrospective cohort study was conducted using medical records of patients with the first symptom onset/diagnosis of ASMD type B or type A/B between 1st January 1990 and 31st July 2021 from four German medical centres. Eligible medical records were abstracted to collect data on demographic characteristics, medical history, hospitalisation, mortality, and causes of death from disease onset to the last follow-up/death. Survival outcomes were estimated using the Kaplan-Meier analysis. Standardised mortality ratio (SMR) was also explored. RESULTS: This study included 33 chart records of patients with ASMD type B (n = 24) and type A/B (n = 9), with a median (interquartile range [IQR]) age of 8.0 [3.0-20.0] years and 1.0 [1.0-2.0] years, respectively, at diagnosis. The commonly reported manifestations were related to spleen (100.0%), liver (93.9%), and respiratory (77.4%) abnormalities. Nine deaths were reported at a median [IQR] age of 17.0 [5.0-25.0] years, with 66.7% of overall patients deceased at less than 18 years of age; the median [IQR] age at death for patients with ASMD type B (n = 4) and type A/B (n = 5) was 31.0 [11.0-55.0] and 9.0 [4.0-18.0] years, respectively. All deaths were ASMD-related and primarily caused by liver or respiratory failures or severe progressive neurodegeneration (two patients with ASMD type A/B). The median (95% confidence interval [CI]) overall survival age since birth was 45.4 (17.5-65.0) years. Additionally, an SMR [95% CI] analysis (21.6 [9.8-38.0]) showed that age-specific deaths in the ASMD population were 21.6 times more frequent than that in the general German population. CONCLUSIONS: This study highlights considerable morbidity and mortality associated with ASMD type B and type A/B in Germany. It further emphasises the importance of effective therapy for chronic ASMD to reduce disease complications.

Long-Term Outcome of Infantile Onset Pompe Disease Patients Treated with Enzyme Replacement Therapy - Data from a German-Austrian Cohort.

BACKGROUND: Enzyme replacement therapy (ERT) with recombinant human alglucosidase alfa (rhGAA) was approved in Europe in 2006. Nevertheless, data on the long-term outcome of infantile onset Pompe disease (IOPD) patients at school age is still limited. OBJECTIVE: We analyzed in detail cardiac, respiratory, motor, and cognitive function of 15 German-speaking patients aged 7 and older who started ERT at a median age of 5 months. RESULTS: Starting dose was 20 mg/kg biweekly in 12 patients, 20 mg/kg weekly in 2, and 40 mg/kg weekly in one patient. CRIM-status was positive in 13 patients (86.7%) and negative or unknown in one patient each (6.7%). Three patients (20%) received immunomodulation. Median age at last assessment was 9.1 (7.0-19.5) years. At last follow-up 1 patient (6.7%) had mild cardiac hypertrophy, 6 (42.9%) had cardiac arrhythmias, and 7 (46.7%) required assisted ventilation. Seven patients (46.7%) achieved the ability to walk independently and 5 (33.3%) were still ambulatory at last follow-up. Six patients (40%) were able to sit without support, while the remaining 4 (26.7%) were tetraplegic. Eleven patients underwent cognitive testing (Culture Fair Intelligence Test), while 4 were unable to meet the requirements for cognitive testing. Intelligence quotients (IQs) ranged from normal (IQ 117, 102, 96, 94) in 4 patients (36.4%) to mild developmental delay (IQ 81) in one patient (9.1%) to intellectual disability (IQ 69, 63, 61, 3x <55) in 6 patients (54.5%). White matter abnormalities were present in 10 out of 12 cerebral MRIs from 7 patients. CONCLUSION: Substantial motor, cardiac, respiratory, and cognitive deficits are frequent in IOPD long-term survivors who started ERT before 2016. The findings of this study can be valuable as comparative data when evaluating the impact of newer treatment strategies including higher enzyme dosage, immunomodulation, modified enzymes, or early start of treatment following newborn screening.

CNS Manifestations in Mucolipidosis Type II-A Retrospective Analysis of Longitudinal Data on Neurocognitive Development and Neuroimaging in Eleven Patients.

Mucolipidosis type II (MLII), an ultra-rare lysosomal storage disorder, manifests as a fatal multi-systemic disease. Mental inhibition and progressive neurodegeneration are commonly reported disease manifestations. Nevertheless, longitudinal data on neurocognitive testing and neuroimaging lack in current literature. This study aimed to provide details on central nervous system manifestations in MLII. All MLII patients with at least one standardized developmental assessment performed between 2005 and 2022 were included by retrospective chart review. A multiple mixed linear regression model was applied. Eleven patients with a median age of 34.0 months (range 1.6-159.6) underwent 32 neurocognitive and 28 adaptive behaviour assessments as well as 14 brain magnetic resonance imagings. The scales used were mainly BSID-III (42%) and VABS-II (47%). Neurocognitive testing (per patient: mean 2.9, standard deviation (SD) 2.0) performed over 0-52.1 months (median 12.1) revealed profound impairment with a mean developmental quotient of 36.7% (SD 20.4) at last assessment. The patients showed sustained development; on average, they gained 0.28 age-equivalent score points per month (confidence interval 0.17-0.38). Apart from common (63%) cervical spinal stenosis, neuroimaging revealed unspecific, non-progressive abnormalities (i.e., mild brain atrophy, white matter lesions). In summary, MLII is associated with profound developmental impairment, but not with neurodegeneration and neurocognitive decline.

Comparison of classical Fabry and its p.D313Y and p.A143T variants by cardiac T1 mapping, LGE and feature tracking myocardial strain.

Cardiac manifestation of classical Fabry disease (cFD) varies with sex and presence of left ventricular hypertrophy. p.D313Y/p.A143T variants (vFD) represent milder late-onset phenotypes, however, data on vFD are scarce. Patients with FD (cFD = 37;vFD = 14) and 14 healthy controls underwent 1.5 T CMR including Cine, LGE, native T1 mapping(nT1) and myocardial strain(CMR-FT). CMR-FT was assessed using ventricular longitudinal, circumferential, radial (LV-GLS/RV-GLS, LV-GCS/LV-GRS), and atrial longitudinal strain (LA/RATotal, LA/RAConduit, LA/RABooster). In cFD reduced myocardial strain (LV-GLS: -20 ± 4 vs. -24 ± 3%,p = 0.007; LV-GCS: -20 ± 4 vs. -26 ± 4%,p = 0.002, LA Total -GLS: 29 ± 10 vs. 37 ± 6%,p = 0.007; LA Conduit -GLS: 15 ± 10 vs. 23 ± 5%,p = 0.003) and nT1 values (951 ± 51 ms vs. 1036 ± 20 ms, p < 0.001) were observed compared to controls. In vFD findings were comparable to controls. LV-GCS provided the closest Area under the curve (AUC) to nT1 (0.84 vs. 0.92, p > 0.05) for discrimination of cFD versus controls. Significantly lower LV-GLS/LV-GCS was found in male compared to female cFD (-19 ± 4 vs. -22 ± 4%, p = 0.03). In six non-hypertrophied female cFD with normal nT1 LATotal -GLS was the only discriminating parameter with an accuracy of 86%. LV-GLS, LV-GCS and LATotal -GLS can detect impaired cardiac mechanics of cFD besides nT1. LATotal -GLS might identify non-hypertrophied female cFD. Variants p.D313Y/p.A143T did not reveal cardiac involvement by multiparametric CMR.

Management, vaccination status and COVID-19 morbidity of patients with Gaucher disease in Germany during the COVID-19 pandemic.

BACKGROUND: Continuation of standard management of Gaucher disease (GD) has been challenging during the COVID-19 pandemic, resulting in infrequent/missed infusions and follow-up appointments. Little data are available on the consequences of these changes and on the SARS-CoV-2 vaccinations in German GD patients. METHODS: A survey with 22 questions about GD management during the pandemic was sent to 19 German Gaucher centres. It was answered by 11/19 centres caring for 257 GD patients (almost ¾ of the German GD population); 245 patients had type 1 and 12 had type 3 GD; 240 were ≥ 18 years old. RESULTS: Monitoring intervals were prolonged in 8/11 centres from a median of 9 to 12 months. Enzyme replacement therapy (ERT) was changed to home ERT in 4 patients and substituted by oral substrate reduction therapy (SRT) in 6 patients. From March 2020 to October 2021, no serious complications of GD were documented. Only 4 SARS-CoV-2 infections were reported (1.6%). Two infections were asymptomatic and two mild; all occurred in adult type 1, non-splenectomized patients on ERT. Vaccination rate in adult GD was 79.5% (95.3% mRNA vaccines). Serious vaccination complications were not reported. CONCLUSIONS: The COVID-19 pandemic has lowered the threshold for switching from practice- or hospital-based ERT to home therapy or to SRT. No major GD complication was documented during the pandemic. Infection rate with SARS-CoV-2 in GD may rather be lower than expected, and its severity is mild. Vaccination rates are high in GD patients and vaccination was well tolerated.

Accumulation of α-synuclein mediates podocyte injury in Fabry nephropathy.

Current therapies for Fabry disease are based on reversing intracellular accumulation of globotriaosylceramide (Gb3) by enzyme replacement therapy (ERT) or chaperone-mediated stabilization of the defective enzyme, thereby alleviating lysosomal dysfunction. However, their effect in the reversal of end-organ damage, like kidney injury and chronic kidney disease, remains unclear. In this study, ultrastructural analysis of serial human kidney biopsies showed that long-term use of ERT reduced Gb3 accumulation in podocytes but did not reverse podocyte injury. Then, a CRISPR/Cas9-mediated α-galactosidase knockout podocyte cell line confirmed ERT-mediated reversal of Gb3 accumulation without resolution of lysosomal dysfunction. Transcriptome-based connectivity mapping and SILAC-based quantitative proteomics identified α-synuclein (SNCA) accumulation as a key event mediating podocyte injury. Genetic and pharmacological inhibition of SNCA improved lysosomal structure and function in Fabry podocytes, exceeding the benefits of ERT. Together, this work reconceptualizes Fabry-associated cell injury beyond Gb3 accumulation, and introduces SNCA modulation as a potential intervention, especially for patients with Fabry nephropathy.

Long-term safety and efficacy of velmanase alfa treatment in children under 6 years of age with alpha-mannosidosis: A phase 2, open label, multicenter study.

Alpha-mannosidosis (AM) is a rare, autosomal recessive, lysosomal storage disorder caused by alpha-mannosidase deficiency that leads to the accumulation of mannose-rich oligosaccharides. AM symptoms and severity vary among individuals; consequently, AM is often not diagnosed until late childhood. Velmanase alfa (VA), a recombinant human lysosomal alpha-mannosidase product, is the first enzyme replacement therapy indicated to treat non-neurological symptoms of AM in Europe. Previous studies suggested that early VA treatment in children may produce greater clinical benefit over the disease course than starting treatment in adolescents or adults; however, long-term studies in children are limited, and very few studies include children under 6 years of age. The present phase 2, multicenter, open-label study evaluated the safety and efficacy of long-term VA treatment in children under 6 years of age with AM. Five children (three males) received VA weekly for ≥24 months, and all children completed the study. Four children experienced adverse drug reactions (16 events) and two experienced infusion-related reactions (12 events). Most (99.5%) adverse events were mild or moderate, and none caused study discontinuation. Four children developed antidrug antibodies (three were neutralizing). After VA treatment, all children improved in one or more efficacy assessments of serum oligosaccharide concentrations (decreases), hearing, immunological profile, and quality of life, suggesting a beneficial effect of early treatment. Although the small study size limits conclusions, these results suggest that long-term VA treatment has an acceptable safety profile, is well tolerated, and may provide potential benefits to patients with AM under 6 years of age.

A phase I/II study on intracerebroventricular tralesinidase alfa in patients with Sanfilippo syndrome type B.

BackgroundSanfilippo type B is a mucopolysaccharidosis (MPS) with a major neuronopathic component characterized by heparan sulfate (HS) accumulation due to mutations in the NAGLU gene encoding alfa-N-acetyl-glucosaminidase. Enzyme replacement therapy for neuronopathic MPS requires efficient enzyme delivery throughout the brain in order to normalize HS levels, prevent brain atrophy, and potentially delay cognitive decline.MethodsIn this phase I/II open-label study, patients with MPS type IIIB (n = 22) were treated with tralesinidase alfa administered i.c.v. The patients were monitored for drug exposure; total HS and HS nonreducing end (HS-NRE) levels in both cerebrospinal fluid (CSF) and plasma; anti-drug antibody response; brain, spleen, and liver volumes as measured by MRI; and cognitive development as measured by age-equivalent (AEq) scores.ResultsIn the Part 1 dose escalation (30, 100, and 300 mg) phase, a 300 mg dose of tralesinidase alfa was necessary to achieve normalization of HS and HS-NRE levels in the CSF and plasma. In Part 2, 300 mg tralesinidase alfa sustained HS and HS-NRE normalization in the CSF and stabilized cortical gray matter volume (CGMV) over 48 weeks of treatment. Resolution of hepatomegaly and a reduction in spleen volume were observed in most patients. Significant correlations were also established between the change in cognitive AEq score and plasma drug exposure, plasma HS-NRE levels, and CGMV.ConclusionAdministration of tralesinidase alfa i.c.v. effectively normalized HS and HS-NRE levels as a prerequisite for clinical efficacy. Peripheral drug exposure data suggest a role for the glymphatic system in altering tralesinidase alfa efficacy.Trial registrationClinicaltrials.gov NCT02754076.FUNDINGBioMarin Pharmaceutical Inc. and Allievex Corporation.

Effects of Infantile Hypophosphatasia on Human Dental Tissue.

Hypophosphatasia (HPP) is an inherited, systemic disorder, caused by loss-of-function variants of the ALPL gene encoding the enzyme tissue non-specific alkaline phosphatase (TNSALP). HPP is characterized by low serum TNSALP concentrations associated with defective bone mineralization and increased fracture risk. Dental manifestations have been reported as the exclusive feature (odontohypophosphatasia) and in combination with skeletal complications. Enzyme replacement therapy (asfotase alfa) has been shown to improve respiratory insufficiency and skeletal complications in HPP patients, while its effects on dental status have been understudied to date. In this study, quantitative backscattered electron imaging (qBEI) and histological analysis were performed on teeth from two patients with infantile HPP before and during asfotase alfa treatment and compared to matched healthy control teeth. qBEI and histological methods revealed varying mineralization patterns in cementum and dentin with lower mineralization in HPP. Furthermore, a significantly higher repair cementum thickness was observed in HPP compared to control teeth. Comparison before and during treatment showed minor improvements in mineralization and histological parameters in the patient when normalized to matched control teeth. HPP induces heterogeneous effects on mineralization and morphology of the dental status. Short treatment with asfotase alfa slightly affects mineralization in cementum and dentin. Despite HPP being a rare disease, its mild form occurs at higher prevalence. This study is of high clinical relevance as it expands our knowledge of HPP and dental involvement. Furthermore, it contributes to the understanding of dental tissue treatment, which has hardly been studied so far.

Early enzyme replacement therapy prevents dental and craniofacial abnormalities in a mouse model of mucopolysaccharidosis type VI.

Mucopolysaccharidosis VI (MPS VI) is a hereditary lysosomal storage disease caused by the absence of the enzyme arylsulfatase B (ARSB). Craniofacial defects are common in MPS VI patients and manifest as abnormalities of the facial bones, teeth, and temporomandibular joints. Although enzyme replacement therapy (ERT) is the treatment of choice for MPS VI, the effects on the craniofacial and dental structures are still poorly understood. In this study, we used an Arsb-deficient mouse model (Arsb m/m ) that mimics MPS VI to investigate the effects of ERT on dental and craniofacial structures and compared these results with clinical and radiological observations from three MPS VI patients. Using micro-computed tomography, we found that the craniofacial phenotype of the Arsb m/m mice was characterized by bone exostoses at the insertion points of the masseter muscles and an overall increased volume of the jaw bone. An early start of ERT (at 4 weeks of age for 20 weeks) resulted in a moderate improvement of these jaw anomalies, while a late start of ERT (at 12 weeks of age for 12 weeks) showed no effect on the craniofacial skeleton. While teeth typically developed in Arsb m/m mice, we observed a pronounced loss of tooth-bearing alveolar bone. This alveolar bone loss, which has not been described before in MPS VI, was also observed in one of the MPS VI patients. Interestingly, only an early start of ERT led to a complete normalization of the alveolar bone in Arsb m/m mice. The temporomandibular joints in Arsb m/m mice were deformed and had a porous articular surface. Histological analysis revealed a loss of physiological cartilage layering, which was also reflected in an altered proteoglycan content in the cartilage of Arsb m/m mice. These abnormalities could only be partially corrected by an early start of ERT. In conclusion, our results show that an early start of ERT in Arsb m/m mice achieves the best therapeutic effects for tooth, bone, and temporomandibular joint development. As the MPS VI mouse model in this study resembles the clinical findings in MPS VI patients, our results suggest enzyme replacement therapy should be started as early as possible.

Sanfilippo syndrome: consensus guidelines for clinical care.

Sanfilippo syndrome is a group of rare, complex, and progressive neurodegenerative lysosomal storage disorders that is characterized by childhood dementia. The clinical management of patients with progressive neurological decline and multisystem involvement requires a multidisciplinary team with experience in the management of neurodegenerative disorders. Best practice guidelines for the clinical management of patients with these types of rare disorders are critical to ensure prompt diagnosis and initiation of appropriate care. However, there are no published standard global clinical care guidelines for patients with Sanfilippo syndrome. To address this, a literature review was conducted to evaluate the current evidence base and to identify evidence gaps. The findings were reviewed by an international steering committee composed of clinical experts with extensive experience in managing patients with Sanfilippo syndrome. The goal was to create a consensus set of basic clinical guidelines that will be accessible to and informed by clinicians globally, as well as providing a practical resource for families to share with their local care team who may not have experience with this rare disease. This review distills 178 guideline statements into an easily digestible document that provides evidence-based, expert-led recommendations for how to approach common management challenges and appropriate monitoring schedules in the care of patients with Sanfilippo syndrome.

Anaesthesia-Relevant Disease Manifestations and Perianaesthetic Complications in Patients with Mucolipidosis-A Retrospective Analysis of 44 Anaesthetic Cases in 12 Patients.

Mucolipidosis (ML) type II, intermediate, and III are lysosomal storage disorders with progressive multiorgan manifestations predisposing patients to a high risk of perioperative morbidity. The aims of the study were to systematically assess disease manifestations relevant to anaesthesia as well as anaesthesia-related complications. This retrospective study includes ML patients who underwent anaesthesia in two centres between 2008 and 2022. We reviewed patients' demographics, medical history, disease manifestations, as well as procedure- and outcome-related data. A total of 12 patients (7 MLII, 2 ML intermediate, 3 MLIII) underwent 44 anaesthesia procedures (per patient: median 3, range 1-11). The median age was 3.3 years (range 0.1-19.1). At least one complication occurred in 27.3% of the anaesthesia procedures. The vast majority of complications (94%) occurred in children with MLII and ML intermediate. A predicted difficult airway was found in 100% and 80% of the MLII and ML intermediate patients, respectively. Accordingly, most complications (59%) occurred during the induction of anaesthesia. Altogether, respiratory complications were the most frequent (18%), followed by difficult airway management (14%). The risk for anaesthesia-related complications is alarmingly high in patients with ML, particularly in those with MLII and ML intermediate. Multidisciplinary risk-benefit analysis and thoughtful anaesthesia planning are crucial in these patients.

Promising Effect of High Dose Ambroxol Treatment on Neurocognition and Motor Development in a Patient With Neuropathic Gaucher Disease 2.

Gaucher Disease (GD) 2 is a rare inherited lysosomal disorder. Early-onset and rapid progression of neurovisceral symptoms lead to fatal outcome in early childhood. Treatment is symptomatic, a curative therapy is currently not available. This prospective study describes the clinical and biochemical outcome of a GD 2 patient treated with high dose ambroxol from the age of 4 months. Due to progressive hepatosplenomegaly additional enzyme replacement therapy was required 1 year after ambroxol monotherapy was initiated. Detailed clinical follow-up data demonstrated an age-appropriate neurocognitive and motor development but no clear benefit on peripheral organs. Glucosylsphingosine (Lyso-GL1) in cerebrospinal fluid decreased remarkably compared to pre-treatment, whereas Lyso-GL1 and chitotriosidase in blood increased. Ambroxol treatment of patient fibroblasts revealed a significant increase in ß-glucocerebrosidase activity in vitro. To our knowledge, this is the first report of a GD 2 patient with age-appropriate cognitive and motor development at 3 years of age. Combination of high dose ambroxol with ERT proved to be a successful approach to manage both visceral and neurological manifestations.

Longitudinal Natural History of Pediatric Subjects Affected with Mucopolysaccharidosis IIIB.

OBJECTIVE: To characterize the longitudinal natural history of disease progression in pediatric subjects affected with mucopolysaccharidosis (MPS) IIIB. STUDY DESIGN: Sixty-five children with a confirmed diagnosis of MPS IIIB were enrolled into 1 of 2 natural history studies and followed for up to 4 years. Cognitive and adaptive behavior functions were analyzed in all subjects, and volumetric magnetic resonance imaging analysis of liver, spleen, and brain, as well as levels of heparan sulfate (HS) and heparan sulfate nonreducing ends (HS-NRE), were measured in a subset of subjects. RESULTS: The majority of subjects with MPS IIIB achieved an apex on both cognition and adaptive behavior age equivalent scales between age 3 and 6 years. Development quotients for both cognition and adaptive behavior follow a linear trajectory by which subjects reach a nadir with a score <25 for an age equivalent of 24 months by age 8 years on average and by 13.5 years at the latest. All tested subjects (n = 22) had HS and HS-NRE levels above the normal range in cerebrospinal fluid and plasma, along with signs of hepatomegaly. Subjects lost an average of 26 mL of brain volume (-2.7%) over 48 weeks, owing entirely to a loss of cortical gray matter (32 mL; -6.5%). CONCLUSIONS: MPS IIIB exists along a continuum based on cognitive decline and cortical gray matter atrophy. Although a few individuals with MPS IIIB have an attenuated phenotype, the majority follow predicted trajectories for both cognition and adaptive behavior. TRIAL REGISTRATION: ClinicalTrials.gov identifiers NCT02493998, NCT03227042, and NCT02754076.

Treatment of Fabry Disease management with migalastat-outcome from a prospective 24 months observational multicenter study (FAMOUS).

AIMS: Fabry disease (FD) is an X-linked lysosomal storage disorder caused by a deficiency of the lysosomal enzyme α-galactosidase A (GLA/AGAL), resulting in the lysosomal accumulation of globotriaosylceramide (Gb3). Patients with amenable GLA mutations can be treated with migalastat, an oral pharmacological chaperone increasing endogenous AGAL activity. In this prospective observational multicentre study, safety as well as cardiovascular, renal, and patient-reported outcomes and disease biomarkers were assessed after 12 and 24 months of migalastat treatment under 'real-world' conditions. METHODS AND RESULTS: A total of 54 patients (26 females) (33 of these [61.1%] pre-treated with enzyme replacement therapy) with amenable mutations were analysed. Treatment was generally safe and well tolerated. A total of 153 events per 1000 patient-years were detected. Overall left ventricular mass index decreased after 24 months (all: -7.5 ± 17.4 g/m2, P = 0.0118; females: -4.6 ± 9.1 g/m2, P = 0.0554; males: -9.9 ± 22.2 g/m2, P = 0.0699). After 24 months, females and males presented with a moderate yearly loss of estimated glomerular filtration rate (-2.6 and -4.4 mL/min/1.73 m2 per year; P = 0.0317 and P = 0.0028, respectively). FD-specific manifestations/symptoms remained stable (all P > 0.05). A total of 76.9% of females and 50% of males suffered from pain, which has not improved under treatment. FD-specific disease scores (Disease Severity Scoring System and Mainz Severity Score Index) remained stable during treatment. AGAL activities and plasma lyso-Gb3 values remained stable, although some male patients presented with increasing lyso-Gb3 levels over time. CONCLUSIONS: Treatment with migalastat was generally safe and resulted in most patients in an amelioration of left ventricular mass. However, due to the heterogeneity of FD phenotypes, it is advisable that the treating physician monitors the clinical response regularly.

Spinal cord compression in patients with mucopolysaccharidosis.

PURPOSE: Spinal abnormalities frequently occur in patients with mucopolysaccharidosis (MPS) types I, II, IV, and VI. The symptoms are manifold, which sometimes prolongs the diagnostic process and delays therapy. Spinal stenosis (SS) with spinal cord compression due to bone malformations and an accumulation of storage material in soft tissue are serious complications of MPS disease. Data on optimal perioperative therapeutic care of SS is limited. METHODS: A retrospective chart analysis of patients with MPS and SS for the time period 01/1998 to 03/2021 was performed. Demographics, clinical data, neurological status, diagnostic evaluations (radiography, MRI, electrophysiology), and treatment modalities were documented. The extent of the SS and spinal canal diameter were analyzed. A Cox regression analysis was performed to identify prognostic factors for neurological outcomes. RESULTS: Out of 209 MPS patients, 15 were included in this study. The most dominant type of MPS was I (-H) (n = 7; 46.7%). Preoperative neurological deterioration was the most frequent indication for further diagnostics (n = 12; 80%). The surgical procedure of choice was dorsal instrumentation with microsurgical decompression (n = 14; 93.3%). A univariate Cox regression analysis showed MPS type I (-H) to be associated with favorable neurological outcomes. CONCLUSION: Early detection of spinal stenosis is highly relevant in patients with MPS. Detailed neurological assessment during follow-up is crucial for timeous detection of patients at risk. The surgical intervention of choice is dorsal instrumentation with microsurgical decompression and resection of thickened intraspinal tissue. Patients with MPS type I (-H) demonstrated the best neurological course.

Understanding disease symptoms and impacts and producing qualitatively-derived severity stages for MPS IIIA: a mixed methods approach.

BACKGROUND: MPS IIIA is a rare, degenerative pediatric genetic disease characterized by symptoms impacting cognition, mobility and behavior; the mean age of death is around 15 years of age. Currently, there are no approved therapies for MPS IIIA. METHODS: A two-year, multi-center, prospective, descriptive cohort study was conducted to document the natural history course of MPS IIIA. In the context of this study, semi-structured interviews were performed with parents of children at study entry and one year later. Interview transcripts were analyzed using thematic analysis methods to identity concepts of interest to children and parents, identify what factors impacted parents' burden the most, and develop qualitatively-derived disease severity stages. Children were sorted into these stages according to the symptoms their parents described at the entry interview. This sorting was compared quantitatively to the sorting of children at baseline according to the child's calendar age and their BSID development quotient (DQ). RESULTS: 22 parents in France, Germany, the Netherlands and the UK were interviewed. Children ranged in age from 28 to 105 months (mean 61.4 months). The conceptual models for children's symptoms and impacts and parents' impacts provided a detailed and comprehensive picture of what it is like for children of various ages and their parents to live with MPS IIIA. Four factors were identified as mediating the burden perceived by parents: state support, family support, time since diagnosis, and parent coping strategy. Four disease stages were developed, accounting for both the presence and the severity of MPS IIIA symptoms. The comparison of children's sorting into these stages with the BSID DQ and the child's calendar age showed strong statistical associations. CONCLUSIONS: The findings of this qualitative research embedded in a natural history study add to the current understanding of MPS IIIA as a complex disease that impacts every aspect of the lives of children and their families. This study demonstrates the unique potential of mixed methods research in rare diseases to address some of the current limitations of more traditional quantitative approaches by providing an individualized, detailed understanding of the patient experience.

An observational, prospective, multicenter, natural history study of patients with mucopolysaccharidosis type IIIA.

Mucopolysaccharidosis type IIIA (MPS IIIA, also known as Sanfilippo syndrome) is a rare genetic lysosomal storage disease characterized by early and progressive neurodegeneration resulting in a rapid decline in cognitive function affecting speech and language, adaptive behavior, and motor skills. We carried out a prospective observational study to assess the natural history of patients with MPS IIIA, using both standardized tests and patient-centric measures to determine the course of disease progression over a 2-year period. A cohort of 23 patients (7 girls, 16 boys; mean age 28-105 months at baseline) with a confirmed diagnosis of MPS IIIA were assessed and followed up at intervals of 3-6 months; cognitive function was measured using Bayley Scales of Infant and Toddler Development 3rd edition (BSID-III) to derive cognitive development quotients (DQ). Daily living, speech/language development and motor skills were measured using the Vineland Adaptive Behavior Scale (VABS-II). Sleep-wake patterns, behavior and quality-of-life questionnaires were also reported at each visit using parent/caregiver reported outcome tools. All patients had early onset severe MPS IIIA, were diagnosed before 74 months of age, and had cognitive scores below normal developmental levels at baseline. Patients less than 40 months of age at baseline were more likely to continue developing new skills over the first 6-12 months of follow-up. There was a high variability in cognitive developmental age (DA) in patients between 40 and 70 months of age; two-thirds of these patients already had profound cognitive decline, with a DA ≤10 months. The highest cognitive DA achieved in the full study cohort was 34 months. Post hoc, patients were divided into two groups based on baseline cognitive DQ (DQ ≥50 or <50). Cognitive DQ decreased linearly over time, with a decrease from baseline of 30.1 and 9.0 points in patients with cognitive DQ ≥50 at baseline and cognitive DQ <50 at baseline, respectively. Over the 2-year study, VABS-II language scores declined progressively. Motor skills, including walking, declined over time, although significantly later than cognitive decline. No clear pattern of sleep disturbance was observed, but night waking was common in younger patients. Pain scores, as measured on the quality-of-life questionnaire, increased over the study period. The findings of this study strengthen the natural history data on cognitive decline in MPS IIIA and importantly provide additional data on endpoints, validated by the patient community as important to treat, that may form the basis of a multidomain endpoint capturing the disease complexity.

Clinical and Genetic Aspects of Juvenile Onset Pompe Disease.

Little is known about clinical symptomatology and genetics of juvenile onset Pompe disease (JOPD). The aims of this study were to analyze how these children are diagnosed, what clinical problems they have, and how phenotype is related to genotype. To accomplish this, we analyzed retrospectively data of 34 patients diagnosed after their first and before completion of their 18th birthday. Median age at diagnosis was 3.9 (range 1.1-17) years. Eight patients (23.5%) developed initial symptoms in the first year, 12 (35%) between 1 and 7 years, and 6 (18%) thereafter. Eight (23.5%) had no clinical symptoms at the time of diagnosis. Indications for diagnostics were a positive family history in three (9%), hyperCKemia in eight (23.5%), motor developmental delay in three (9%), and muscle weakness and/or pain in 17 (50%). Rare clinical signs were failure to thrive, recurrent diarrhea, and suspected hepatopathy with glycogen storage. Thirty-two different mutations were identified. Twenty-seven patients (79.5%) carried the milder c.32-13T > G mutation, known to be associated with a broad range of phenotypes. Three out of eight patients manifesting within the first year of life showed generalized muscle weakness, hypertrophic cardiomyopathy, and had to be ventilated during the course of disease, thereby demonstrating clinical overlap with infantile onset Pompe disease.These findings demonstrate that the phenotype of JOPD is broad and that the differential is not only restricted to neuromuscular disorders. Genotypic analysis was useful to delineate subjects with early onset JOPD from those with IOPD, but overall genotype-phenotype correlation was poor.