A cross-sectional analysis of clinical evaluation in 35 individuals with mutations of the valosin-containing protein gene

Remote respiratory resistance exercise training improves respiratory function in individuals with VCP multisystem proteinopathy

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. H2O (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.

Provisional practice recommendation for the management of myopathy in VCP-associated multisystem proteinopathy

Valosin-containing protein (VCP)-associated multisystem proteinopathy (MSP) is a rare genetic disorder with abnormalities in the autophagy pathway leading to various combinations of myopathy, bone diseases, and neurodegeneration. Ninety percent of patients with VCP-associated MSP have myopathy, but there is no consensus-based guideline. The goal of this working group was to develop a best practice set of provisional recommendations for VCP myopathy which can be easily implemented across the globe. As an initiative by Cure VCP Disease Inc., a patient advocacy organization, an online survey was initially conducted to identify the practice gaps in VCP myopathy. All prior published literature on VCP myopathy was reviewed to better understand the different aspects of management of VCP myopathy, and several working group sessions were conducted involving international experts to develop this provisional recommendation. VCP myopathy has a heterogeneous clinical phenotype and should be considered in patients with limb-girdle muscular dystrophy phenotype, or any myopathy with an autosomal dominant pattern of inheritance. Genetic testing is the only definitive way to diagnose VCP myopathy, and single-variant testing in the case of a known familial VCP variant, or multi-gene panel sequencing in undifferentiated cases can be considered. Muscle biopsy is important in cases of diagnostic uncertainty or lack of a definitive pathogenic genetic variant since rimmed vacuoles (present in ~40% cases) are considered a hallmark of VCP myopathy. Electrodiagnostic studies and magnetic resonance imaging can also help rule out disease mimics. Standardized management of VCP myopathy will optimize patient care and help future research initiatives.

Genotype-phenotype correlations in valosin-containing protein disease: a retrospective muticentre study

BACKGROUND

Valosin-containing protein (VCP) disease, caused by mutations in the VCP gene, results in myopathy, Paget's disease of bone (PBD) and frontotemporal dementia (FTD). Natural history and genotype-phenotype correlation data are limited. This study characterises patients with mutations in VCP gene and investigates genotype-phenotype correlations.

METHODS

Descriptive retrospective international study collecting clinical and genetic data of patients with mutations in the VCP gene.

RESULTS

Two hundred and fifty-five patients (70.0% males) were included in the study. Mean age was 56.8±9.6 years and mean age of onset 45.6±9.3 years. Mean diagnostic delay was 7.7±6 years. Symmetric lower limb weakness was reported in 50% at onset progressing to generalised muscle weakness. Other common symptoms were ventilatory insufficiency 40.3%, PDB 28.2%, dysautonomia 21.4% and FTD 14.3%. Fifty-seven genetic variants were identified, 18 of these no previously reported. c.464G>A (p.Arg155His) was the most frequent variant, identified in the 28%. Full time wheelchair users accounted for 19.1% with a median time from disease onset to been wheelchair user of 8.5 years. Variant c.463C>T (p.Arg155Cys) showed an earlier onset (37.8±7.6 year) and a higher frequency of axial and upper limb weakness, scapular winging and cognitive impairment. Forced vital capacity (FVC) below 50% was as risk factor for being full-time wheelchair user, while FVC <70% and being a full-time wheelchair user were associated with death.

CONCLUSION

This study expands the knowledge on the phenotypic presentation, natural history, genotype-phenotype correlations and risk factors for disease progression of VCP disease and is useful to improve the care provided to patient with this complex disease.

Development of a standard of care for patients with valosin-containing protein associated multisystem proteinopathy

Valosin-containing protein (VCP) associated multisystem proteinopathy (MSP) is a rare inherited disorder that may result in multisystem involvement of varying phenotypes including inclusion body myopathy, Paget’s disease of bone (PDB), frontotemporal dementia (FTD), parkinsonism, and amyotrophic lateral sclerosis (ALS), among others. An international multidisciplinary consortium of 40+ experts in neuromuscular disease, dementia, movement disorders, psychology, cardiology, pulmonology, physical therapy, occupational therapy, speech and language pathology, nutrition, genetics, integrative medicine, and endocrinology were convened by the patient advocacy organization, Cure VCP Disease, in December 2020 to develop a standard of care for this heterogeneous and under-diagnosed disease. To achieve this goal, working groups collaborated to generate expert consensus recommendations in 10 key areas: genetic diagnosis, myopathy, FTD, PDB, ALS, Charcot Marie Tooth disease (CMT), parkinsonism, cardiomyopathy, pulmonology, supportive therapies, nutrition and supplements, and mental health. In April 2021, facilitated discussion of each working group’s conclusions with consensus building techniques enabled final agreement on the proposed standard of care for VCP patients. Timely referral to a specialty neuromuscular center is recommended to aid in efficient diagnosis of VCP MSP via single-gene testing in the case of a known familial VCP variant, or multi-gene panel sequencing in undifferentiated cases. Additionally, regular and ongoing multidisciplinary team follow up is essential for proactive screening and management of secondary complications. The goal of our consortium is to raise awareness of VCP MSP, expedite the time to accurate diagnosis, define gaps and inequities in patient care, initiate appropriate pharmacotherapies and supportive therapies for optimal management, and elevate the recommended best practices guidelines for multidisciplinary care internationally.

Six-Minute Walk Distance Is a Useful Outcome Measure to Detect Motor Decline in Treated Late-Onset Pompe Disease Patients

Late-onset Pompe disease (LOPD) is a rare, progressive disorder characterized by limb–girdle muscle weakness and/or respiratory insufficiency, caused by acid alpha-glucosidase (GAA) gene mutations and treated with enzyme replacement therapy. We studied isometric muscle strength in eight muscle groups bilaterally using a Biodex® dynamometer, as well as the Medical Research Council sum score (MRC-SS), hand grip strength, 6 min walk distance (6MWD), 10 m walk test (10MWT) and timed up-and-go test (TUG) in 12 adult, ambulatory, treated LOPD patients and 12 age-/gender-matched healthy controls, every 6 months for 2 years. The mean isometric muscle strength showed a significant decline in right and left knee extensors at 12 months in controls (p < 0.014; p < 0.016), at 18 months in patients (p < 0.010; p < 0.007) and controls (only right side, p < 0.030) and at 24 months in both groups (p < 0.035). The mean 6MWD in patients significantly decreased after 24 months, from 451.9 m to 368.1 m (p < 0.003), whereas in controls, the mean 6MWD significantly increased after 6 months (p < 0.045) and 18 months (p < 0.020) (at 24 months p = 0.054). In patients and controls, the MRC-SS, hand grip test, 10MWT and TUG did not show significant changes (p > 0.05). We conclude that the 6MWD is a useful outcome measure to detect motor decline in treated LOPD patients.

Phenotypic diversity in an international Cure VCP Disease registry

Background

Dominant mutations in valosin-containing protein (VCP) gene cause an adult onset inclusion body myopathy, Paget’s disease of bone, and frontotemporal dementia also termed multisystem proteinopathy (MSP). The genotype-phenotype relationships in VCP-related MSP are still being defined; in order to understand this better, we investigated the phenotypic diversity and patterns of weakness in the Cure VCP Disease Patient Registry.

Methods

Cure VCP Disease, Inc. was founded in 2018 for the purpose of connecting patients with VCP gene mutations and researchers to help advance treatments and cures. Cure VCP Disease Patient Registry is maintained by Coordination of Rare Diseases at Sanford. The results of two questionnaires with a 5-point Likert scale questions regarding to patients’ disease onset, symptoms, and daily life were obtained from 59 participants (28 males and 31 females) between June 2018 and May 2020. Independent of the registry, 22 patients were examined at the Cure VCP Disease annual patient conference in 2019.

Results

In the questionnaires of the registry, fifty-three patients (90%) reported that they were with inclusion body myopathy, 17 patients (29%) with Paget’s disease of bone, eight patients (14%) with dementia, two patients (3%) with amyotrophic lateral sclerosis, and a patient with parkinsonism. Thirteen patients (22%) reported dysphagia and 25 patients (42%) reported dyspnea on exertion. A self-reported functional rating scale for motor function identified challenges with sit to stand (72%), walking (67%), and climbing stairs (85%). Thirty-five (59%) patients in the registry answered that their quality of life is more than good. As for the weakness pattern of the 22 patients who were evaluated at the Cure VCP Disease annual conference, 50% of patients had facial weakness, 55% had scapular winging, 68% had upper proximal weakness, 41% had upper distal weakness, 77% had lower proximal, and 64% had lower distal weakness.

Conclusions

The Cure VCP Disease Patient Registry is useful for deepening the understanding of patient daily life, which would be a basis to develop appropriate clinical outcome measures. The registry data is consistent with previous studies evaluating VCP patients in the clinical setting. Patient advocacy groups are essential in developing and maintaining disease registries.

The Overlapping Genetics of Amyotrophic Lateral Sclerosis and Frontotemporal Dementia

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two diseases that form a broad neurodegenerative continuum. Considerable effort has been made to unravel the genetics of these disorders, and, based on this work, it is now clear that ALS and FTD have a significant genetic overlap. TARDBP, SQSTM1, VCP, FUS, TBK1, CHCHD10, and most importantly C9orf72, are the critical genetic players in these neurological disorders. Discoveries of these genes have implicated autophagy, RNA regulation, and vesicle and inclusion formation as the central pathways involved in neurodegeneration. Here we provide a summary of the significant genes identified in these two intrinsically linked neurodegenerative diseases and highlight the genetic and pathological overlaps.