Inclusion body myopathy, Paget's disease of the bone and frontotemporal dementia: recurrence of the VCP R155H mutation in an Italian family and implications for genetic counselling

Psychological Impact of Predictive Genetic Testing for Inherited Alzheimer Disease and Frontotemporal Dementia: The IT-DIAfN Protocol

AIM

Our aim was to evaluate the psychological impact of predictive genetic testing in individuals at-risk for inherited dementia who underwent a structured counseling and testing protocol.

METHODS

Participants were healthy at-risk relatives from families with at least one affected patient, in whom a disease-associated genetic variant had been ascertained. A comprehensive psychological assessment (personality, anxiety and depression, quality of life, coping strategies, resilience and health-related beliefs) was administered at baseline, at 6 months and 12 months follow-up.

RESULTS

Twenty-four participants from 13 families were included. Sixteen participants underwent blood sampling and genetic analysis; 6 resulted to be carriers of pathogenic variants (1 in PSEN1, 1 in PSEN2, 4 in GRN). Carriers showed higher score on the Resilience Scale for Adults (RSA) - social competence, and on Multidimensional Health Locus of Control - internal, than noncarriers (P=0.03 for both). Ten at-risk relatives who completed the follow-up showed improvement in RSA - planned future (P=0.01) with respect to baseline.

DISCUSSION

Our case series showed that at-risk individuals undergoing predictive testing showed benefit on personal life and no detrimental impact on a broad range of psychological outcomes. Higher social skills and lower internal health locus of control in carriers may be an early psychological correlate of preclinical dementia.

Clinical, Biochemical, Radiological, and Genetic Analyses of a Patient with VCP Gene Variant-Induced Paget's Disease of Bone

Paget's disease of bone (PDB) is a rare metabolic bone disorder, which is extremely rare in Asian population. This study aimed to investigate the phenotypes and the pathogenic mutations of woman with early-onset PDB. The clinical features, bone mineral density, x-ray, radionuclide bone scan, and serum levels of alkaline phosphatase (ALP), procollagen type 1 N-terminal propeptide (P1NP), and β-carboxy-terminal cross-linked telopeptide of type 1 collagen (β-CTX) were measured in detail. The pathogenic mutations were identified by whole-exon sequencing and confirmed by Sanger sequencing. We also evaluated the effects of intravenous infusion of zoledronic acid on the bones of the patient and summarized the phenotypic characteristics of reported patients with mutation at position 155 of the valosin-containing protein (VCP). The patient only exhibited bone pain as the initial manifestation with vertebral compression fracture and extremely elevated ALP, P1NP, and β-CTX levels; she had no inclusion body myopathy and frontotemporal dementia. The missense mutation in exon 5 of the VCP gene (p.Arg155His) was identified by whole-exome sequencing and further confirmed by Sanger sequencing. No mutation in candidate genes of PDB, such as SQSTM1, CSF1, TM7SF4, OPTN, PFN1, and TNFRSF11A, were identified in the patient by Sanger sequencing. Rapid relief of bone pain and a marked decline in ALP, P1NP, and β-CTX levels were observed after zoledronic acid treatment. Previously reported patients with VCP missense mutation at position 155 (R155H) always had myopathy, frontotemporal dementia, and PDB, but the patient in this study exhibited only PDB. This was the first report of R155H mutation-induced early-onset in the VCP gene in Asian population. PDB was the only manifestation having a favorable response to zoledronic acid treatment. We broadened the genetic and clinical phenotype spectra of the VCP mutation.

Valosin Containing Protein (VCP): A Multistep Regulator of Autophagy

Valosin containing protein (VCP) has emerged as a central protein in the regulation of the protein quality control (PQC) system. VCP mutations are causative of multisystem proteinopathies, which include neurodegenerative diseases (NDs), and share various signs of altered proteostasis, mainly associated with autophagy malfunctioning. Autophagy is a complex multistep degradative system essential for the maintenance of cell viability, especially in post-mitotic cells as neurons and differentiated skeletal muscle cells. Interestingly, many studies concerning NDs have focused on autophagy impairment as a pathological mechanism or autophagy activity boosting to rescue the pathological phenotype. The role of VCP in autophagy has been widely debated, but recent findings have defined new mechanisms associated with VCP activity in the regulation of autophagy, showing that VCP is involved in different steps of this pathway. Here we will discuss the multiple activity of VCP in the autophagic pathway underlying its leading role either in physiological or pathological conditions. A better understanding of VCP complexes and mechanisms in regulating autophagy could define the altered mechanisms by which VCP directly or indirectly causes or modulates different human diseases and revealing possible new therapeutic approaches for NDs.

Structural insight into mutations at 155 position of valosin containing protein (VCP) linked to inclusion body myopathy with Paget disease of bone and frontotemporal Dementia

Mutations in Valosin-containing protein (VCP) have been implicated in the pathology linked to inclusion body myopathy, paget disease of bone and frontotemporal dementia (IBMPFD). VCP is an essential component of AAA-ATPase superfamily involved in various cellular functions. Advanced In-silico analysis was performed using prediction based servers to determine the most deleterious mutation. Molecular dynamics simulation was used to study the protein dynamics at atomic level. Molecular docking was used to study the effect of mutation on ATP/ADP transition in the kinase domain. This ATPase of 806 amino acids has four domains: N-terminal domain, C-terminal domain and two ATPase domains D1 and D2 and each of these domains have a distinct role in its functioning. The mutations in VCP protein are distributed among regions known as hotspots, one such hotspot is codon 155. Three missense mutations reported in this hotspot are R155C, R155H and R155P. Potentiality of the deleteriousness calculated using server based prediction models reveal R155C mutation to be the most deleterious. The atomic insight into the effect of mutation by molecular dynamics simulation revealed major conformational changes in R155C variants ATP binding site in D1 domain. The nucleotide-binding mode at the catalytic pocket of VCP and its three variants at codon 155 showed change in the structure, which affects the ATP-ADP transition kinetics in all the three variants.

An autopsy report of a familial amyotrophic lateral sclerosis case carrying VCP Arg487His mutation with a unique TDP-43 proteinopathy

We here report an autopsy case of familial amyotrophic lateral sclerosis (ALS) with p.Arg487His mutation in the valosin-containing protein (VCP) gene (VCP), in which upper motor neurons (UMNs) were predominantly involved. Moreover, our patient developed symptoms of frontotemporal dementia later in life and pathologically exhibited numerous phosphorylated transactivation response DNA-binding protein of 43 kDa (p-TDP-43)-positive neuronal cytoplasmic inclusions and short dystrophic neurites with a few lentiform neuronal intranuclear inclusions, sharing the features of frontotemporal lobar degeneration with TDP-43 pathology type A pattern. A review of previous reports of ALS with VCP mutations suggests that our case is unique in terms of its UMN-predominant lesion pattern and distribution of p-TDP-43 pathology. Thus, this case report effectively expands the clinical and pathological phenotype of ALS in patients with a VCP mutation.

Neuroimaging in genetic frontotemporal dementia and amyotrophic lateral sclerosis

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) have a strong clinical, genetic and pathological overlap. This review focuses on the current understanding of structural, functional and molecular neuroimaging signatures of genetic FTD and ALS. We overview quantitative neuroimaging studies on the most common genes associated with FTD (MAPT, GRN), ALS (SOD1), and both (C9orf72), and summarize visual observations of images reported in the rarer genes (CHMP2B, TARDBP, FUS, OPTN, VCP, UBQLN2, SQSTM1, TREM2, CHCHD10, TBK1).

Next Generation Sequencing Analysis in Early Onset Dementia Patients

Background:

Early onset dementias (EOD) are rare neurodegenerative dementias that present before 65 years. Genetic factors have a substantially higher pathogenetic contribution in EOD patients than in late onset dementia.

Objective:

To identify known and/or novel rare variants in major candidate genes associated to EOD by high-throughput sequencing. Common-risk variants of apolipoprotein E (APOE) and prion protein (PRNP) genes were also assessed.

Methods:

We studied 22 EOD patients recruited in Memory Clinics, in the context of studies investigating genetic forms of dementia. Two methodological approaches were applied for the target-Next Generation Sequencing (NGS) analysis of these patients. In addition, we performed progranulin plasma dosage, C9Orf72 hexanucleotide repeat expansion analysis, and APOE genotyping.

Results:

We detected three rare known pathogenic mutations in the GRN and PSEN2 genes and eleven unknown-impact mutations in the GRN, VCP, MAPT, FUS, TREM2, and NOTCH3 genes. Six patients were carriers of only common risk variants (APOE and PRNP), and one did not show any risk mutation/variant. Overall, 69% (n = 9) of our early onset Alzheimer’s disease (EAOD) patients, compared with 34% (n = 13) of sporadic late onset Alzheimer’s disease (LOAD) patients and 27% (n = 73) of non-affected controls (ADNI, whole genome data), were carriers of at least two rare/common risk variants in the analyzed candidate genes panel, excluding the full penetrant mutations.

Conclusion:

This study suggests that EOD patients without full penetrant mutations are characterized by higher probability to carry polygenic risk alleles that patients with LOAD forms. This finding is in line with recently reported evidence, thus suggesting that the genetic risk factors identified in LOAD might modulate the risk also in EOAD.

Genotype-phenotype links in frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) represents a group of neurodegenerative brain diseases with highly heterogeneous clinical, neuropathological and genetic characteristics. This high degree of heterogeneity results from the presence of several different underlying molecular disease processes; consequently, it is unlikely that all patients with FTLD will benefit from a single therapy. Therapeutic strategies for FTLD are currently being explored, and tools are urgently needed that enable the selection of patients who are the most likely to benefit from a particular therapy. Definition of the phenotypic characteristics in patients with different FTLD subtypes that share the same underlying disease processes would assist in the stratification of patients into homogeneous groups. The most common subtype of FTLD is characterized by TAR DNA-binding protein 43 (TDP43) pathology (FTLD-TDP). In this group, pathogenic mutations have been identified in four genes: C9orf72, GRN, TBK1 and VCP. Here, we provide a comprehensive overview of the phenotypic characteristics of patients with FTLD-TDP, highlighting shared features and differences among groups of patients who have a pathogenic mutation in one of these four genes.

New ALS-Related Genes Expand the Spectrum Paradigm of Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is characterized by the degeneration of upper and lower motor neurons. Clinical heterogeneity is a well-recognized feature of the disease as age of onset, site of onset and the duration of the disease can vary greatly among patients. A number of genes have been identified and associated to familial and sporadic forms of ALS but the majority of cases remains still unexplained. Recent breakthrough discoveries have demonstrated that clinical manifestations associated with ALS-related genes are not circumscribed to motor neurons involvement. In this view, ALS appears to be linked to different conditions over a continuum or spectrum in which overlapping phenotypes may be identified. In this review, we aim to examine the increasing number of spectra, including ALS/Frontotemporal Dementia and ALS/Myopathies spectra. Considering all these neurodegenerative disorders as different phenotypes of the same spectrum can help to identify common pathological pathways and consequently new therapeutic targets in these incurable diseases.

Mutations in the Human AAA+ Chaperone p97 and Related Diseases

A number of neurodegenerative diseases have been linked to mutations in the human protein p97, an abundant cytosolic AAA⁺ (ATPase associated with various cellular activities) ATPase, that functions in a large number of cellular pathways. With the assistance of a variety of cofactors and adaptor proteins, p97 couples the energy of ATP hydrolysis to conformational changes that are necessary for its function. Disease-linked mutations, which are found at the interface between two main domains of p97, have been shown to alter the function of the protein, although the pathogenic mutations do not appear to alter the structure of individual subunit of p97 or the formation of the hexameric biological unit. While exactly how pathogenic mutations alter the cellular function of p97 remains unknown, functional, biochemical and structural differences between wild-type and pathogenic mutants of p97 are being identified. Here, we summarize recent progress in the study of p97 pathogenic mutants.

One family, one gene and three phenotypes: A novel VCP (valosin-containing protein) mutation associated with myopathy with rimmed vacuoles, amyotrophic lateral sclerosis and frontotemporal dementia

BACKGROUND

VCP (valosin-containing protein gene) variants have been associated with peripheral and central neurodegenerative processes, including inclusion body myopathy (IBM), Paget disease of bone (PDB), frontotemporal dementia (FTD), and familial amyotrophic lateral sclerosis (ALS) type 14. The combination of IBM, PDB (IBMPFD1) can presented in one individual. However, the association of IBMPFD1 and ALS in the same family is rare.

METHODS

We reported three individuals from a Brazilian kindred with intrafamilial phenotype variability. Whole exome sequencing (WES) of the proband was performed and revealed a novel VCP variant. VCP Sanger sequencing was performed in the proband and his family members to confirm WES finding and segregation. We performed a systematic review of the literature regarding the genotypic-phenotypic VCP correlations.

RESULTS

Each individual presented with either myopathy with rimmed vacuoles, ALS, or FTD. There was no PDB. WES of the proband identified the heterozygous variant c.271A>T (p.Asn91Tyr) in the exon 3 of VCP. Sanger sequencing confirmed the segregation of this variant in an autosomal-dominant pattern.

CONCLUSION

This study expands the genotypic spectrum of the missense mutations of the VCP gene with a novel p.Asn91Tyr variant found in a Brazilian family presenting with the unusual intrafamiliar association of myopathy with rimmed vacuoles, ALS and FTD.

Targeted excision of VCP R155H mutation by Cre-LoxP technology as a promising therapeutic strategy for valosin-containing protein disease

Inclusion body myopathy associated with Paget's disease of the bone and frontotemporal dementia is attributed to mutations in the valosin-containing protein (VCP) gene, mapped to chromosomal region 9p13.3-12. Affected individuals exhibit scapular winging and die from progressive muscle weakness and cardiac and respiratory failure in their 40s to 50s. Mutations in the VCP gene have also been associated with amyotrophic lateral sclerosis in 10-15% of individuals with hereditary inclusion body myopathy and 2-3% of isolated familial amyotrophic lateral sclerosis. Currently, there are no effective treatments for VCP-related myopathy or dementia. To determine the effects of targeted excision of the most common R155H mutation in VCP disease, we generated the Cre-ER™-VCPR155H/+ tamoxifen-inducible model. We administered tamoxifen (0.12 mg/g body weight) or corn oil (vehicle) to the pregnant dams by oral gavage and monitored survival and muscle strength measurements of the pups until 18 months of age. We confirmed efficient removal of exons 4 and 5 and recombination of the mutant/floxed VCP copies by Q-PCR analyses. The activity and specificity of Cre recombinase was confirmed by immunostaining. Herein, we report that Cre-ER™-VCPR155H/+ mice demonstrated improved muscle strength and quadriceps fibers architecture, autophagy signaling pathway, reduced brain neuropathology, decreased apoptosis, and less severe Paget-like bone changes. The Cre-ER™-VCPR155H/+ mouse model provides proof of principle by demonstrating that removal of the mutated exons could be beneficial to patients with VCP-related neurodegenerative diseases, and serves as an excellent platform in understanding the underlying pathophysiological mechanism(s) in the hopes of a promising therapeutic approach.

Rapamycin and chloroquine: the in vitro and in vivo effects of autophagy-modifying drugs show promising results in valosin containing protein multisystem proteinopathy

Mutations in the valosin containing protein (VCP) gene cause hereditary Inclusion body myopathy (hIBM) associated with Paget disease of bone (PDB), frontotemporal dementia (FTD), more recently termed multisystem proteinopathy (MSP). Affected individuals exhibit scapular winging and die from progressive muscle weakness, and cardiac and respiratory failure, typically in their 40s to 50s. Histologically, patients show the presence of rimmed vacuoles and TAR DNA-binding protein 43 (TDP-43)-positive large ubiquitinated inclusion bodies in the muscles. We have generated a VCP^R155H/+ mouse model which recapitulates the disease phenotype and impaired autophagy typically observed in patients with VCP disease. Autophagy-modifying agents, such as rapamycin and chloroquine, at pharmacological doses have previously shown to alter the autophagic flux. Herein, we report results of administration of rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR) signaling pathway, and chloroquine, a lysosomal inhibitor which reverses autophagy by accumulating in lysosomes, responsible for blocking autophagy in 20-month old VCP^R155H/+ mice. Rapamycin-treated mice demonstrated significant improvement in muscle performance, quadriceps histological analysis, and rescue of ubiquitin, and TDP-43 pathology and defective autophagy as indicated by decreased protein expression levels of LC3-I/II, p62/SQSTM1, optineurin and inhibiting the mTORC1 substrates. Conversely, chloroquine-treated VCP^R155H/+ mice revealed progressive muscle weakness, cytoplasmic accumulation of TDP-43, ubiquitin-positive inclusion bodies and increased LC3-I/II, p62/SQSTM1, and optineurin expression levels. Our in vitro patient myoblasts studies treated with rapamycin demonstrated an overall improvement in the autophagy markers. Targeting the mTOR pathway ameliorates an increasing list of disorders, and these findings suggest that VCP disease and related neurodegenerative multisystem proteinopathies can now be included as disorders that can potentially be ameliorated by rapalogs.

Immunoreactivity of valosin-containing protein in sporadic amyotrophic lateral sclerosis and in a case of its novel mutant

Background

Mutations in the valosin-containing protein (VCP) gene were first found to cause inclusion- body myopathy with early-onset Paget disease and frontotemporal dementia (IBMPFD). Mutations in the VCP gene were later reported to occur in familial amyotrophic lateral sclerosis (ALS). But the role of VCP in the neurodegenerative processes that occur in ALS remains unknown. The purpose of the present study was to elucidate the role of VCP in the neurodegeneration seen in sporadic and VCP mutant ALS.

Results

Immunohistochemistry demonstrated that the frequency of distinct VCP-positive nuclei of spinal motor neurons of patients with sporadic ALS (SALS) and the ALS with VCP novel mutation (ALS-VCP, M158V) was increased, compared with that of the control cases. No VCP-positive inclusion bodies were observed in SALS patients, a ALS-VCP patient or in control subjects. Neuropathologic examination of the ALS-VCP case showed loss of motor neurons, the presence of Bunina bodies, and degeneration of the corticospinal tracts. Bunina bodies detected in this case were confirmed to show immunohistochemical and ultrastructural features similar to those previously described. Furthermore, neuronal intracytoplasmic inclusions immunopositive for TAR DNA-binding protein 43 kDa (TDP-43), phosphorylated TDP-43, ubiquitin (Ub), p62, and optineurin were identified in the spinal and medullary motoneurons, but not in the neocortex. Gene analysis of this ALS-VCP patient confirmed the de novo mutation of M158V, which was not found in control cases; and bioinformatics using several in silico analyses showed possible damage to the structure of VCP. Immunocytochemical study of cultured cells showed increased cytoplasmic translocation of TDP-43 in cells transfected with several mutant VCP including our patient’s compared with wild-type VCP.

Conclusion

These findings support the idea that VCP is associated with the pathomechanism of SALS and familial ALS with a VCP mutation, presumably acting through a dominant-negative mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-014-0172-0) contains supplementary material, which is available to authorized users.

Paget's disease of bone

Paget's disease is an osteoclastic-mediated disorder of bone that results in abnormal bone resorption associated with inadequate remodeling that leads to mechanically weakened bone. Demonstrating variable geographic prevalence, it is becoming less frequent and age of onset is lengthening in areas of once high prevalence prior to the institution of effective medical therapies, suggesting its etiology involves both environmental as well as genetic factors. Insights into its pathophysiology are helping to clarify other inherited osteolytic disorders of bone by providing additional insights into related cellular processes.

Psychiatric Presentation of Frontotemporal Dementia Associated with Inclusion Body Myopathy due to the VCP Mutation (R155H) in a French Family

Introduction

Inclusion body myopathy with Paget's disease of the bone and frontotemporal dementia (IBMPFD) is a rare late-onset autosomal dominant disorder due to a mutation of the valosin-containing protein (VCP) gene.

Case Report

We report the case of a patient who developed progressive weakness of the limbs in his fifties, until he was confined to a wheelchair. At that time, he developed acute behavioural changes including irritability, severe anxiety and major depression, which led to him being hospitalised in a psychiatric hospital. He also suffered from aphasia and executive function impairment, which helped us to diagnose a behavioural form of frontotemporal dementia (FTD). The diagnosis of IBMPFD due to a mutation in the VCP gene was confirmed by a genetic study of the VCP gene (R155H mutation).

Discussion

The clinical diagnosis of IBMPFD is suggested by the presence of at least one of three major manifestations as follows: inclusion body myopathy (mean onset at 42 years of age), Paget's disease of the bone and FTD (mean onset at 55 years of age). It is mostly the behavioural form of FTD (behavioural changes, executive dysfunction and aphasia). One interesting finding in our report is the predominance of the psychiatric symptoms at the beginning of the behavioural changes, which led to the diagnosis of FTD. The diagnosis of IBMPFD was confirmed by the genetic study: the R155H mutation found on exon 5 domain CDC48 is the most frequent of the 18 known mutations in the VCP gene.

Exercise training reverses skeletal muscle atrophy in an experimental model of VCP disease

Background

The therapeutic effects of exercise resistance and endurance training in the alleviation of muscle hypertrophy/atrophy should be considered in the management of patients with advanced neuromuscular diseases. Patients with progressive neuromuscular diseases often experience muscle weakness, which negatively impact independence and quality of life levels. Mutations in the valosin containing protein (VCP) gene lead to Inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia (IBMPFD) and more recently affect 2% of amyotrophic lateral sclerosis (ALS)-diagnosed cases.

Methods/Principle Findings

The present investigation was undertaken to examine the effects of uphill and downhill exercise training on muscle histopathology and the autophagy cascade in an experimental VCP mouse model carrying the R155H mutation. Progressive uphill exercise in VCP^R155H/+ mice revealed significant improvement in muscle strength and performance by grip strength and Rotarod analyses when compared to the sedentary mice. In contrast, mice exercised to run downhill did not show any significant improvement. Histologically, the uphill exercised VCP^R155H/+ mice displayed an improvement in muscle atrophy, and decreased expression levels of ubiquitin, P62/SQSTM1, LC3I/II, and TDP-43 autophagy markers, suggesting an alleviation of disease-induced myopathy phenotypes. There was also an improvement in the Paget-like phenotype.

Conclusions

Collectively, our data highlights that uphill exercise training in VCP^R155H/+ mice did not have any detrimental value to the function of muscle, and may offer effective therapeutic options for patients with VCP-associated diseases.

[A case of inclusion body myopathy with Paget's disease of bone and frontotemporal dementia (IBMPFD) showing clinical features of motor neuron disease]

Inclusion body myopathy with Paget's disease of bone and frontotemporal dementia (IBMPFD) is caused by mutations in the valosin-containing protein (VCP) gene. Varied clinical features caused by VCP mutations have been reported: these clinical phenotypes include distal myopathy, frontotemporal dementia and amyotrophic lateral sclerosis. We report a 49-year-old woman with 3-year history of progressive proximal limb muscle weakness. Family history was notable for her father with motor neuron disease and an elder brother with a myopathy involving tibialis anterior and quadriceps. Neurological examinations showed proximal muscle atrophy, especially severe atrophy of paravertebral muscles, right-dominant scapular winging, bilateral pyramidal signs and hyperreflexia. Serum CK level was normal and EMG showed chronic neurogenic changes. Muscle imaging (CT) showed adipose tissue replacement of paravertebral muscles and right serratus anterior, and marked atrophy of bilateral trapezius and vastus intermedius muscles. Her lumbar spine X-ray showed an osteosclerotic change in the vertebral body, where an increased uptake of Tc99m was also observed in bone scintigraphy. Although brain MRI was normal, neuropsychological examination showed a mild attention deficit with cognitive impairment. A muscle biopsy specimen revealed scattered fibers with rimmed vacuoles. These findings prompted us to analyze a mutation in the VCP gene. Genomic sequencing of all exons of the gene showed a heterozygous missense mutation in exon 5 (c.1315G>C; p.Ala439Pro).

Novel mutation in VCP gene causes atypical amyotrophic lateral sclerosis

OBJECTIVE

To identify the genetic variant that causes autosomal dominantly inherited motor neuron disease in a 4-generation Israeli-Arab family using genetic linkage and whole exome sequencing.

METHODS

Genetic linkage analysis was performed in this family using Illumina single nucleotide polymorphism chips. Whole exome sequencing was then undertaken on DNA samples from 2 affected family members using an Illumina 2000 HiSeq platform in pursuit of potentially pathogenic genetic variants that comigrate with the disease in this pedigree. Variants meeting these criteria were then screened in all affected individuals.

RESULTS

A novel mutation (p.R191G) in the valosin-containing protein (VCP) gene was identified in the index family. Direct sequencing of the VCP gene in a panel of DNA from 274 unrelated individuals with familial amyotrophic lateral sclerosis (FALS) revealed 5 additional mutations. Among them, 2 were previously identified in pedigrees with a constellation of inclusion body myopathy with Paget disease of the bone and frontotemporal dementia (IBMPFD) and in FALS, and 2 other mutations (p.R159C and p.R155C) in IBMPFD alone. We did not detect VCP gene mutations in DNA from 178 cases of sporadic amyotrophic lateral sclerosis.

CONCLUSIONS

We report a novel VCP mutation identified in an amyotrophic lateral sclerosis family (p.R191G) with atypical clinical features. In our experience, VCP mutations arise in approximately 1.5% of FALS cases. Our study supports the view that motor neuron disease is part of the clinical spectrum of VCP-associated disease.

The homozygote VCP(R¹⁵⁵H/R¹⁵⁵H) mouse model exhibits accelerated human VCP-associated disease pathology

Valosin containing protein (VCP) mutations are the cause of hereditary inclusion body myopathy, Paget's disease of bone, frontotemporal dementia (IBMPFD). VCP gene mutations have also been linked to 2% of isolated familial amyotrophic lateral sclerosis (ALS). VCP is at the intersection of disrupted ubiquitin proteasome and autophagy pathways, mechanisms responsible for the intracellular protein degradation and abnormal pathology seen in muscle, brain and spinal cord. We have developed the homozygous knock-in VCP mouse (VCP(R155H/R155H)) model carrying the common R155H mutations, which develops many clinical features typical of the VCP-associated human diseases. Homozygote VCP(R155H/R155H) mice typically survive less than 21 days, exhibit weakness and myopathic changes on EMG. MicroCT imaging of the bones reveal non-symmetrical radiolucencies of the proximal tibiae and bone, highly suggestive of PDB. The VCP(R155H/R155H) mice manifest prominent muscle, heart, brain and spinal cord pathology, including striking mitochondrial abnormalities, in addition to disrupted autophagy and ubiquitin pathologies. The VCP(R155H/R155H) homozygous mouse thus represents an accelerated model of VCP disease and can be utilized to elucidate the intricate molecular mechanisms involved in the pathogenesis of VCP-associated neurodegenerative diseases and for the development of novel therapeutic strategies.

Paget's Disease of Bone: A Review of Epidemiology, Pathophysiology and Management

Paget's disease of bone is a common disorder which may affect one or many bones. Although many patients are asymptomatic, a variety of symptoms and complications may occur. Fortunately, effective pharmacologic therapy, primarily with potent bisphosphonates, is now available to treat patients with complications or symptoms. This review of Paget's disease of bone will include epidemiology and pathophysiology, complications and clinical findings, indications for treatment, and the drugs currently available to treat this condition.

VCP disease associated with myopathy, Paget disease of bone and frontotemporal dementia: review of a unique disorder

Inclusion body myopathy (IBM) associated with Paget disease of the bone (PDB) and frontotemporal dementia (FTD) (now called IBMPFD), is a progressive autosomal dominant disorder that was recently identified as being caused by mutations in the VCP (p97 or CDC48) gene which plays a key role in the ubiquitin-proteasome dependent degradation of cytosolic proteins and in the retro translocation of misfolded proteins from the endoplasmic reticulum into the cytoplasm. Approximately 90% of the affected persons in the study have myopathy or muscle weakness particularly of the shoulder and hip girdles, which can lead to loss of walking ability and even death by complications of respiratory and cardiac failure. About half of affected study participants have Paget disease of bone characterized by abnormal rates of bone growth that can result in bone pain, enlargement and fractures. Findings of premature FTD affecting behavior and personality are seen in a third of affected individuals. Within 20 IBMPFD families whose data was analyzed for this study, ten missense mutations have been identified, the majority of which are located in the N-terminal ubiquitin binding domain. Inclusions seen in the muscle, brain and heart in VCP disease contain ubiquitin, beta amyloid and TDP-43, also seen in other neurodegenerative disorders thus implicating common pathways in their pathogenesis.