VCP disease, also known as multisystem proteinopathy, is a rare, autosomal dominant, adult-onset, neuromuscular disease that is caused by variants in the valosin-containing protein (VCP) gene. VCP disease may exhibit one or more of the following primary features: inclusion body myopathy, Paget’s disease of bone (PDB), Frontotemporal dementia, and amyotrophic lateral sclerosis. Due to its progressive nature, death normally occurs in their sixties due to respiratory and cardiac failure. The purpose of this study is to utilize the Cure VCP Disease patient registry hosted by the Coordination of Rare Diseases at Sanford (CoRDS) to conduct a prospective natural history study. Seventy-nine participants enrolled in the patient registry and answered demographic, VCP variant type, Patient-reported outcome measures (PROMs), and quality of life (QOL) questionnaires over the course of 3 years. We additionally investigated if any sex differences existed and if genotype–phenotype correlations affected the rate of progression of the varying clinical manifestations. Overall, participants’ mobility declined significantly as the disease progressed. Participants reported a 0.6

Fabry disease (FD) is a rare multi-systemic lysosomal storage disease that affects the heart and kidneys most significantly. An underappreciated manifestation of FD is reduced bone mineral density. Currently, there are no specific guidelines for routine bone density assessments, and treatment of osteoporosis and osteopenia in FD. To ascertain the frequency of low bone mineral density in FD we studied dual-energy x-ray absorptiometry (DXA) scans obtained as part of routine care from a cohort of 25 individuals followed at the University of California—Irvine Medical Center for the period 2008–2023. The most recent BMD results for the lumbar spine and femoral neck were collected from 12 males and 13 females to examine the prevalence of low bone mineral density. The lowest Z- and/or T-scores of either lumbar spine or femoral neck were selected for analysis. Demographic factors, disease and ERT status, and other laboratory values were collected concurrently (within ± 9 months) with DXA scan results and were analyzed with Z- and T-scores to assess for correlations. In our cohort the mean age was 51 years (median 56 years, range 18–77 years). The Z-scores for all participants and T-scores from postmenopausal women and men ≥ 50-year-old were analyzed and correlated with various measures including disease duration, BMI, renal function (measured by eGFR), plasma GL3, Lyso-GL3, calcium, vitamin D, and alkaline phosphatase levels. These parameters were concurrent with DXA scan results. The average Z-score for all the participants was −1.2 ± 1.3 (range −4.6 to 1.6). Twenty-four percent of all participants (n = 6) had significantly low Z-scores ≤ −2.0. To identify the frequency of subjects with osteopenia, defined as T-score between −1.0 and −2.5 and osteoporosis defined as T-score < −2.5, T-scores were analyzed in postmenopausal women (n = 8) and men 50 years and older (n = 7). Of these 15 individuals, average T-score was −2.2 ± 1.3 (range −5.4 to 0.3), and 86.7

Heat shock protein family B (small) member 8 (HSPB8) promotes chaperone-assisted selective autophagy (CASA), which assures proteostasis in muscles and neurons. HSPB8 frameshift mutations found in neuromyopathies are translated on the same frame, generating the same C-terminal extension, which causes HSPB8 aggregation and proteostasis defects. Here, we describe three novel HSPB8 frameshift variants, translated to protein using the third alternative frame to stop codons downstream to the canonical one and to the one used by other known HSPB8 frameshift mutants. Therefore, these variants are predicted to encode a C-terminal extension that is different in length and amino acids. HSPB8 c.562delC and c.520_523delTACT were identified in two unrelated sporadic patients, while c.515delC, in a familial case of early-onset myopathy. Patients may differentially exhibit additional pathological features, such as neuropathy, respiratory insufficiency, and, remarkably, severe cardiomyopathy. Skeletal muscle biopsies revealed variations in fiber size, atrophy, multiple vacuoles, fat infiltration, and eosinophilic inclusions. In a reconstituted cell model of disease the expression of one representative novel HSPB8 mutant results in i) aggregation of the HSPB8 mutant, ii) sequestration of both the HSPB8 wild-type and CASA complex members, as well as iii) the autophagy receptor sequestosome-1 (SQSTM1/p62), iv) accumulation of ubiquitinated substrates, and v) defects in CASA-mediated degradation. Our results prove that the last exon of the HSPB8 gene is highly susceptible to pathogenic mutations, resulting in a wider phenotypic spectrum associated with HSPB8 frameshift variants. Our studies suggest the importance of HSPB8 genetic testing not only for neuropathy and myopathy but also for cardiomyopathy.

Background and Objectives:β-mannosidosis is an ultra-rare lysosomal storage disorder caused by a deficiency of β-mannosidase, which catalyzes the last step of glycoprotein degradation. Owing to the limited number of reported cases, information on the natural history of the disease and brain imaging is scarce. We report 6 new cases and review them together with all the previously reported cases in the literature. Methods:We describe the clinical features of 6 unrelated patients with β-mannosidosis, their variants in MANBA, enzyme activity, urine oligosaccharide profiles, brain MRI findings, and longitudinal MRI changes in 2 of them. We also review previously reported patients to broaden the spectrum of clinical features and identify genotype-phenotype correlations. Results:Developmental regression, dysphagia, obsessive-compulsive-like behavior, and erythromelalgia are newly described features associated with β-mannosidosis among the 6 patients from our cohort. Nystagmus in association with β-mannosidosis was also found in 1 patient. Half the patients have abnormal brain MRIs, showing delayed myelination before 2 years of age and diffuse hypomyelination thereafter. A new oligosaccharide was found in the urine of the 2 most severely affected patients. Including our 6 patients, a total of 46 cases from 37 different families have been reported. The mean age of diagnosis is 12.8 years, and the mean age of symptom onset is 2.4 years. Hearing loss was the initial symptom most frequently reported, and intellectual disability was the most frequent symptom overall. Across the cohort, 29 pathogenic MANBA variants were identified, 61.8% were private, and 38.2% have the recurrent c.2158-2A>G variant. Neuroimaging abnormalities were reported in 40% of published cases and included cortical and subcortical atrophy, basal ganglia and white matter calcification, hydrocephalus, periventricular and subcortical white matter hyperintensities, and delayed myelination. Discussion:Genotype-phenotype correlation in β-mannosidosis remains elusive, likely due to phenotypic variability, disease rarity, and lack of association between the enzyme activity and the clinical severity. Modifier genes in the N-glycan degradation pathway, such as CTBS, may influence disease expression. β-mannosidosis should be considered as a differential diagnosis in patients with syndromic or apparently nonsyndromic hearing loss, unexplained brain hypomyelination, behavioral disturbances, and intellectual disability.

Pompe disease (PD) is a progressive myopathy caused by the aberrant accumulation of glycogen in skeletal and cardiac muscle resulting from the deficiency of the enzyme acid alpha-glucosidase (GAA). Administration of recombinant human GAA as enzyme replacement therapy (ERT) works well in alleviating the cardiac manifestations of PD but loses sustained benefit in ameliorating the skeletal muscle pathology. The limited efficacy of ERT in skeletal muscle is partially attributable to its inability to curb the accumulation of new glycogen produced by the muscle enzyme glycogen synthase 1 (GYS1). Substrate reduction therapies aimed at knocking down GYS1 expression represent a promising avenue to improve Pompe myopathy. However, finding specific inhibitors for GYS1 is challenging given the presence of the highly homologous GYS2 in the liver. Antisense oligonucleotides (ASOs) are chemically modified oligomers that hybridise to their complementary target RNA to induce their degradation with exquisite specificity. In the present study, we show that ASO-mediated Gys1 knockdown in the Gaa-/- mouse model of PD led to a robust reduction in glycogen accumulation in skeletal muscle. In addition, combining Gys1 ASO with ERT slightly further reduced glycogen content in muscle, eliminated autophagic buildup and lysosomal dysfunction, and improved motor function in Gaa-/- mice. Our results provide a strong foundation for validation of the use of Gys1 ASO, alone or in combination with ERT, as a therapy for PD. We propose that early administration of Gys1 ASO in combination with ERT may be the key to preventative treatment options in PD.Key points Antisense oligonucleotide (ASO) treatment in a mouse model of Pompe disease achieves robust knockdown of glycogen synthase (GYS1). ASO treatment reduces glycogen content in skeletal muscle. Combination of ASO and enzyme replacement therapy (ERT) further improves motor performance compared to ASO alone in a mouse model of Pompe disease.

MECP2 Duplication Syndrome, also known as X-linked intellectual developmental disorder Lubs type (MRXSL; MIM: 300260), is a neurodevelopmental disorder caused by copy number gains spanning MECP2. Despite varying genomic rearrangement structures, including duplications and triplications, and a wide range of duplication sizes, no clear correlation exists between DNA rearrangement and clinical features. We had previously demonstrated that up to 38

Valosin-containing protein (VCP) disease is an autosomal dominant multisystem proteinopathy associated with hereditary inclusion body myopathy, Paget disease of bone, and frontotemporal dementia. Myopathy frequently results in respiratory muscle weakness, leading to early mortality due to respiratory failure. We investigated the effects of a remotely administered inspiratory muscle training program in individuals with VCP disease. Nine adults with VCP mutation-positive familial myopathy without evidence of dementia were recruited for a 40-week remotely administered study. Baseline performance was established during the first 8 weeks, followed by 32 weeks of inspiratory muscle training. The primary outcome was maximum inspiratory pressure (MIP). The secondary and exploratory endpoints included spirometry, grip strength, Inclusion Body Myopathy Functional Rating Scale (IBMFRS), Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS), timed up and go, and six-minute walk test (6MWT). During the treatment phase, MIP increased significantly by a weekly mean of 0.392cm. H2 O ( p = 0.023). In contrast, grip strength and ALSFRS significantly decreased by 0.088 lbs. ( p = 0.031) and 0.043 points ( p = 0.004) per week, respectively, as expected from the natural progression of this disease. A remotely administered inspiratory muscle training program is therefore feasible, safe, and well-tolerated in individuals with VCP disease and results in improved inspiratory muscle strength. (c) 2023 Published by Elsevier B.V.

Abstract Disclosure: E.F. Gevers: Advisory Board Member; Self; Pfizer, Inc., Soleno. Research Investigator; Self; Soleno Therapeutics, Inc.. Speaker; Self; Pfizer, Inc., Novo Nordisk, Soleno Therapeutics, Inc. J.L. Miller: Research Investigator; Self; Soleno Therapeutics, Inc. N.A. Bridges: Research Investigator; Self; Soleno Therapeutics, Inc. E.I. Felner: Research Investigator; Self; Soleno Therapeutics, Inc. P. Salehi: Research Investigator; Self; Soleno Therapeutics, Inc. D. Stevenson: Research Investigator; Self; Soleno Therapeutics, Inc. J. Yanovski: Research Investigator; Self; Soleno Therapeutics, Inc. L. Bird: Research Investigator; Self; Soleno Therapeutics, Inc. V. Kimonis: Research Investigator; Self; Soleno Therapeutics, Inc. A.H. Shoemaker: Research Investigator; Self; Soleno Therapeutics, Inc. K.S. Obrynba: Research Investigator; Self; Soleno Therapeutics, Inc. M. Lah: Research Investigator; Self; Soleno Therapeutics, Inc. E. Littlejohn: Research Investigator; Self; Soleno Therapeutics, Inc. N. Cowen: Employee; Self; Soleno Therapeutics, Inc.. Stock Owner; Self; Soleno Therapeutics, Inc. N. Cowen: Employee; Self; Soleno Therapeutics, Inc.. Stock Owner; Self; Soleno Therapeutics, Inc. K. Yen: Employee; Self; Soleno Therapeutics, Inc.. Stock Owner; Self; Soleno Therapeutics, Inc. S. Ballal: Employee; Self; Soleno Therapeutics, Inc.. Stock Owner; Self; Soleno Therapeutics, Inc. P. Hirano: Employee; Self; Soleno Therapeutics, Inc.. Stock Owner; Self; Soleno Therapeutics, Inc. M. Huang: Employee; Self; Soleno Therapeutics, Inc.. Stock Owner; Self; Soleno Therapeutics, Inc. A. Bhatnagar: Employee; Self; Soleno Therapeutics, Inc.. Stock Owner; Self; Soleno Therapeutics, Inc.. Background: Prader-Willi syndrome (PWS) is a rare genetic neurobehavioral-metabolic disease characterized by hyperphagia, endocrinopathies, weight gain, hypotonia, behavioral problems, and an increased risk of mortality and reduced life expectancy. There are currently no approved treatments for hyperphagia in PWS. Diazoxide choline extended-release (DCCR) is a novel, once daily oral therapy being developed for the treatment of PWS. Herein, we present results of the Randomized Withdrawal Period (RWP) of Clinical Study C602, a long-term treatment study of DCCR in people with PWS. Objectives and Methods: This was a 16-week multi-center, double-blind, placebo-controlled RWP that enrolled participants ≥4 years of age who were actively enrolled in the open label period of Clinical Study C602 and had received 2-4 years of DCCR treatment (target dose: ≥3.3 mg/kg; optimal range: 4.2-5.8 mg/kg) at the time of RWP entry. RWP-eligible participants were randomized 1:1 to continue DCCR or withdraw from DCCR and receive Placebo. The primary objective was to evaluate the effect of continued DCCR administration versus Placebo on hyperphagia based on the change in Hyperphagia Questionnaire for Clinical Trials (HQ-CT) Total Score from Baseline to Week 16. Additional endpoints included: the Clinical Global Impression of Severity (CGI-S) and Clinical Global Impression of Improvement (CGI-I) at Week 16; changes in body composition (weight, BMI, and BMI z-scores) at Week 16; and the safety profile of DCCR. Results: DCCR (n=38) and Placebo (n=39) groups were generally balanced for demographic and baseline characteristics. At Week 16, a statistically significant difference in change from baseline in HQ-CT Total Score was observed between DCCR and Placebo groups with HQ-CT Total Scores increasing markedly (indicating worsening hyperphagia) in the Placebo group compared to the DCCR group (LSMean difference [SE] -5.0 [1.57], p=0.002). CGI-S and CGI-I showed trends towards worsening in the Placebo group versus the DCCR group (p=0.079 and 0.092, respectively). The Placebo group also experienced significantly greater increases in weight, BMI, and BMI z-scores (p=0.035, 0.034, and 0.023, respectively) than the DCCR group. DCCR was well-tolerated, with no new or unexpected safety signals, and no serious adverse events or discontinuations due to adverse events in the DCCR group. Conclusions: In this 16-week RWP, the Placebo group experienced significant worsening in hyperphagia and increases in body weight, BMI, and BMI z-scores, along with worsening trends for the CGI-S and CGI-I, compared to the DCCR group. DCCR was well tolerated, with a safety profile that was consistent with prior experience. These data suggest treatment with DCCR may lead to clinical benefits in people with PWS by reducing hyperphagia and improving body composition. Presentation: 6/2/2024

Multisystem Proteinopathy 1 (MSP1) disease is a rare genetic disorder caused by mutations in the Valosin-Containing Protein (VCP) gene with clinical features of inclusion body myopathy (IBM), frontotemporal dementia (FTD), and Paget’s disease of bone (PDB). We performed bone scan imaging in twelve patients (6 females, 6 males) with confirmed VCP gene mutation six (50%) of which has myopathy alone, four (33%) with both PDB and myopathy, and two (15%) were presymptomatic carriers. We aim to characterize the PDB in diagnosed individuals, and potentially identify PDB in the myopathy and presymptomatic groups. Interestingly, two patients with previously undiagnosed PDB had positive diagnostic findings on the bone scan and subsequent radiograph imaging. Among the individuals with PDB, increased radiotracer uptake of the affected bones were of typical distribution as seen in conventional PDB and those reported in other MSP1 cohorts which are the thoracic spine and ribs (75%), pelvis (75%), shoulder (75%) and calvarium (15%). Overall, we show that technetium-99m bone scans done at regular intervals are a sensitive screening tool in patients with MSP1 associated VCP variants at risk for PDB. However, diagnostic confirmation should be coupled with clinical history, biochemical analysis, and skeletal radiographs to facilitate early treatment and prevention complications, acknowledging its limited specificity.