Increased frequency of impaired fasting glucose and isolated systolic hypertension in Paget's disease of bone

PURPOSE

Scanty data about glucose metabolism and hypertension have been reported in Paget's disease of bone (PDB) to be related with increased cardiovascular mortality. The aim of the present study was to evaluate glucose and blood pressure levels in PDB, looking for their association with disease severity.

METHODS

We performed an observational cross-sectional study in 54 patients with PDB and 54 age, sex and BMI-matched controls. Glucose and blood pressure levels and parameters of bone and mineral metabolism were assessed.

RESULTS

Patients with PDB showed increased glucose levels (6.3 ± 1.7 vs 5.3 ± 1.4 mmol/l, p < 0.001) and prevalence of impaired fasting glucose (14.8%, 5.3-24.3 vs 1.9%, 0-5.4, p < 0.02) as well as enhanced systolic blood pressure (145.9 ± 21.3 vs 132.9 ± 18.9 mmHg, p < 0.005), pulse pressure (69.6 ± 20.0 vs 56.0 ± 16.9 mmHg, p < 0.01) and prevalence of isolated systolic hypertension (46.3%, 33.0-59.6 vs 16.7%, 6.7-26.6, p < 0.003) in comparison to controls. Moreover, we found a positive association of (1) glucose levels with ionized calcium and bone alkaline phosphatase; (2) both systolic and pulse pressure with total and bone alkaline phosphatase (p < 0.05). By multiple linear regression analysis (R² = 0.26; p < 0.05) serum ionized calcium correlated with glucose levels (β = 0.44; p < 0.04), after adjusting for age and BMI.

CONCLUSIONS

Our study shows increased fasting glucose, systolic and pulse pressure levels as well as enhanced prevalence of impaired fasting glucose and isolated systolic hypertension in PDB, potentially accounting for increased cardiovascular mortality. Furthermore, our findings suggest high serum calcium and/or increased bone alkaline phosphatase as a link between PDB and cardio-metabolic disorders.

Dental Manifestations of Pediatric Bone Disorders

PURPOSE OF REVIEW

Several bone disorders affecting the skeleton often are manifest in the maxillofacial region. This review presents the most common bone disorders in children and their dental-oral manifestations: fibrous dysplasia, Paget's disease, osteogenesis imperfecta, renal osteodystrophy, hypophosphatasia, and osteoporosis. The specific intraoral characteristics will reviewed in detail.

RECENT FINDINGS

Recent studies confirmed the close relationship between the mandible and the maxilla with the most prevalent systemic bone disorders in children. This review will help practitioners to integrate the oral health into the systemic health and improve the multidisciplinary approach of pediatric patients between medicine and dentistry.

Total Hip Arthroplasty in Paget's Disease A Review

Paget's disease of the bone is a chronic osteopathy that leads to structural weakness, hypervascularity, and bone deformities. Rapid bone turnover in patients with Paget's disease may affect outcomes following total hip arthroplasty (THA). Most literature on THA in the setting of Paget's disease is limited to isolated case reports or case series documenting a single institution experience. By completing a comprehensive analysis of the available cases, this study aims to investigate the outcomes and complications of THA in patients with Paget's disease.

Bone Quality in Paget's Disease of Bone

Paget's disease of bone is produced by a localized increase in osteoclastic and osteoblastic activity which can progress slowly to involve an entire bone if untreated. A common feature is enlarged bones which are deformed, particularly in weight-bearing regions of the skeleton such as the lower extremity. Pathologic fractures may be a consequence, and nonunion of femoral fractures is not uncommon. Analyses of bone biopsies from patients with Paget's disease indicate that there is a lower, heterogeneous degree of bone mineralization and a younger tissue age than that found in control bone. Pagetic bone also has less resistance to plastic deformation and a straighter crack path than control bone.

Paget's disease of bone-genetic and environmental factors

Paget's disease of bone is generally diagnosed in individuals aged >50 years, usually manifests in one or several bones and is initiated by osteoclast-induced osteolytic lesions. Subsequently, over a period of many years, osteoblastic activity can result in sclerosis and deformation of bone. The prevalence of Paget's disease is highest in the UK and in countries where a large number of residents have ancestors from the UK. Currently, in many countries, the prevalence of the disorder has decreased. A considerable number of affected patients have a family history of Paget's disease and the disorder has an autosomal dominant pattern of inheritance but with incomplete penetrance. A large number of mutations in SQSTM1 (which encodes sequestosome-1; also known as ubiquitin-binding protein p62) seem to account for the susceptibility to develop Paget's disease in some families; the involvement of other genes is currently under investigation. In addition to a genetic cause, environmental factors have been proposed to have a role in the pathogenesis of Paget's disease. Although most evidence has been presented for measles virus as an aetiologic factor, some studies have not confirmed its involvement. The decreasing incidence of Paget's disease, which could be attributed to measles vaccination along with the measles virus nucleocapsid protein induction of Paget's disease lesions in transgenic mice, supports an aetiologic role of the virus.

NF-κB signaling and bone resorption

The transcription factor NF-κB is a family of proteins involved in signaling pathways essential for normal cellular functions and development. Deletion of various components of this pathway resulted with abnormal skeletal development. Research in the last decade has established that NF-κB signaling mediates RANK ligand-induced osteoclastogenesis. Consistently, it was shown that inhibition of NF-κB was an effective approach to inhibit osteoclast formation and bone resorptive activity. Identification of the molecular machinery underlying NF-κB activation permitted osteoclast-specific deletion of the major components of this pathway. As a result, it was clear that deletion of members of the proximal IKK kinase complex and the distal NF-κB subunits and downstream regulators affected skeletal development. These studies provided several targets of therapeutic intervention in osteolytic diseases. NF-κB activity has been also described as the centerpiece of inflammatory responses and is considered a potent mediator of inflammatory osteolysis. Indeed, inflammatory insults exacerbate physiologic RANKL-induced NF-κB signals leading to exaggerated responses and to inflammatory osteolysis. These superimposed NF-κB activities appear to underlie several bone pathologies. This review will describe the individual roles of NF-κB molecules in bone resorption and inflammatory osteolysis.

Genotype-phenotype correlation in juvenile Paget disease: role of molecular alterations of the TNFRSF11B gene

Juvenile Paget disease (JPD) {MIM 239000} is a rare inherited bone disease that affects children. The patients affected with JPD present an altered bone turnover, therefore, show a phenotype characterized by progressive bone deformities, fractures, and short stature. Deletions or missense mutations of the TNFRSN11B gene are common in these children. This gene encodes a soluble protein, the osteoprotegerin, which leads to uncontrolled osteoclastogenesis when mutated. JPD is characterized by a strong genotype-phenotype correlation, so depending on the alteration of the TNFRSN11B gene, the phenotype is variable. This review describes the different clinical features which are characteristic of JPD and the correspondence with the different molecular alterations of the TNFRSN11B gene.

[Computed tomographic criteria for the diagnosis of variable manifestations of Paget's disease in the cerebral cranium and facial bones]

OBJECTIVE

to optimize the diagnosis of different stages of Paget's disease, by determining the extent of bone structural lesions in the cerebral and visceral cranium on the basis of computed tomography data.

MATERIAL AND METHODS

Computed tomographic data were assessed by keeping in mind the structure, density, outlines, shadow shapes of the described tumor-like disease and the state of involved bone structures. Twelve patients with histologically verified Paget's disease were examined.

RESULTS

The findings allowed the high informative value of computed tomography in diagnosing different stages of Paget's disease to be estimated in bone structural lesions in the cerebral and visceral cranium and skull base. Also, the obtained computed tomography data permitted the tracing of the extent of the lesion in the area under study.

Emerging strategies and therapies for treatment of Paget's disease of bone

Paget's disease of bone (PDB) is a progressive monostotic or polyostotic metabolic bone disease characterized by focal abnormal bone remodeling, with increased bone resorption and excessive, disorganized, new bone formation. PDB rarely occurs before middle age, and it is the second most frequent metabolic bone disorder after osteoporosis, affecting up to 3% of adults over 55 years of age. One of the most striking and intriguing clinical features is the focal nature of the disorder, in that once the disease is established within a bone, there is only local spread within that bone and no systemic dissemination. Despite many years of intense research, the etiology of PDB has still to be conclusively determined. Based on a detailed review of genetic and viral factors incriminated in PDB, we propose a unifying hypothesis from which we can suggest emerging strategies and therapies. PDB results in weakened bone strength and abnormal bone architecture, leading to pain, deformity or, depending on the bone involved, fracture in the affected bone. The diagnostic assessment includes serum total alkaline phosphatase, total body bone scintigraphy, skull and enlarged view pelvis x-rays, and if needed, additional x-rays. The ideal therapeutic option would eliminate bone pain, normalize serum total alkaline phosphatase with prolonged remission, heal radiographic osteolytic lesions, restore normal lamellar bone, and prevent recurrence and complications. With the development of increasingly potent bisphosphonates, culminating in the introduction of a single intravenous infusion of zoledronic acid 5 mg, these goals of treatment are close to being achieved, together with long-term remission in almost all patients. Based on the recent pathophysiological findings, emerging strategies and therapies are reviewed: ie, pulse treatment with zoledronic acid; denosumab, a fully human monoclonal antibody directed against RANK ligand; tocilizumab, an interleukin-6 receptor inhibitor; odanacatib, a cathepsin K inhibitor; and proteasome and Dickkopf-1 inhibitors.

Paget's disease of bone: the skeletal distribution, complications and quality of life as perceived by patients

CONTEXT

Paget's disease of bone (PDB) is a focal disorder of bone metabolism with overgrowth of affected bone resulting in the skeletal complications of this disease.

OBJECTIVE

This study examines what patients know about the skeletal distribution of their PDB, and correlates this with their reports of complications and quality of life.

DESIGN

The New England Registry for PDB (NRPD) is a voluntary registry with a questionnaire linked to a radiographic database. Data were collected by mail beginning in 2001.

SETTING

Ambulatory population.

PATIENTS

Any patient with PDB living in New England was eligible to enroll; 285 elected to participate, mean age 73.2 years.

MAIN OUTCOME MEASURES

Patients were asked what bones were affected by PDB, and whether they suffered complications from PDB. Radiographic studies were sought to corroborate their responses. An SF-12 was administered.

RESULTS

Compared to the general population, they reported substantially lower levels of physical health (Physical Component Score (PCS) mean=40), and slightly better mental health (Mental Component Score (MCS) mean=52). There were more instances of agreement on disease presence and fewer instances on disagreement (p=0.001). Radiographic studies supported the presence of a complication from PDB when deformity, fracture and joint replacement had occurred, but were less correlative when headache or hearing loss was reported.

CONCLUSIONS

Most patients with PDB are aware of the skeletal distribution of their disease; there is a reasonable correlate between complications ascribed to PDB and the presence of PDB on the radiograph except when headache or hearing loss is reported.

Recent advances in understanding the molecular basis of Paget disease of bone

Paget disease of bone (PDB) is a relatively common disorder characterised by increased bone turnover within discrete lesions throughout the skeleton. The condition has a strong genetic component, with mutations affecting the SQSTM1 gene that encodes the p62 protein often found in PDB patients, although environmental factors also play an important role in disease aetiology. The precise disease mechanism(s) in familial forms and sporadic forms of PDB is unclear, although defective RANK-NF-kappaB signalling has been suggested to contribute to the increased activity of pagetic osteoclasts in the former. Here, there is a review of recent advances in the understanding of the molecular basis of PDB with particular emphasis on findings since 2008, and focus on newly defined functions of the p62 protein upon which SQSTM1 mutations may impact in the development of the pagetic phenotype.

Paget's disease 1: epidemiology, causes and clinical features

The first in this two-part unit on Paget's disease outlines the epidemiology, pathophysiology, causes and clinical features of this long-term bone condition.

Meaning behind measurement: self-comparisons affect responses to health-related quality of life questionnaires

PURPOSE

The subjective nature of quality of life is particularly pertinent to the domain of health-related quality of life (HRQOL) research. The extent to which participants' responses are affected by subjective information and personal reference frames is unknown. This study investigated how an elderly population living with a chronic metabolic bone disorder evaluated self-reported quality of life.

METHODS

Participants (n = 1,331) in a multi-centre randomised controlled trial for the treatment of Paget's disease completed annual HRQOL questionnaires, including the SF-36, EQ-5D and HAQ. Supplementary questions were added to reveal implicit reference frames used when making HRQOL evaluations. Twenty-one participants (11 male, 10 female, aged 59-91 years) were interviewed retrospectively about their responses to the supplementary questions, using cognitive interviewing techniques and semi-structured topic guides.

RESULTS

The interviews revealed that participants used complex and interconnected reference frames to promote response shift when making quality of life evaluations. The choice of reference frame often reflected external factors unrelated to individual health. Many participants also stated that they were unclear whether to report general or disease-related HRQOL.

CONCLUSIONS

It is important, especially in clinical trials, to provide instructions clarifying whether 'quality of life' refers to disease-related HRQOL. Information on self-comparison reference frames is necessary for the interpretation of responses to questions about HRQOL.

Paget's disease: epidemiology and pathophysiology

Paget's disease of bone is a focal disorder of aging bone. The classic late-onset Paget's disease is often caused by a P392L mutation in the gene SQSTM1, which disturbs signaling pathways in osteoclasts on cell activation. This prevalent mutation is neither necessary nor sufficient to cause Paget's disease. Its identification, along with the elucidation of other mutations underlying early-onset Paget's and Paget's disease seen in association with inclusion body myopathy and frontotemporal dementia, have redefined our understanding of genetic disorders of bone remodeling by emphasizing the importance of environmental determinants in their pathophysiology.

Pathogenesis of Paget's disease of bone

Paget's disease of bone is a common condition characterised by increased and disorganised bone turnover which can affect one or several bones throughout the skeleton. These abnormalities disrupt normal bone architecture and lead to various complications such as bone pain osteoarthritis, pathological fracture, bone deformity, deafness, and nerve compression syndromes. Genetic factors play an important role in PDB and mutations or polymorphisms have been identified in four genes that cause classical Paget's disease and related syndromes. These include TNFRSF11A, which encodes RANK, TNFRSF11B which encodes osteoprotegerin, VCP which encodes p97, and SQSTM1 which encodes p62. All of these genes play a role in the RANK-NFkappaB signalling pathway and it is likely that the mutations predispose to PDB by disrupting normal signalling, leading to osteoclast activation. Although Paget's has traditionally be considered a disease of the osteoclast there is evidence that stromal cell function and osteoblast function are also abnormal, which might account for the fact that the disease is associated with increased bone formation as well as resorption. Environmental factors also contribute to Paget's disease. Most research has focused on paramyxovirus infection as a possible environmental trigger but evidence in favour of the involvement of viruses in the disease remains conflicting. Other factors which have been implicated as possible disease triggers include mechanical loading, dietary calcium and environmental toxins. Further work will be required to identify additional genetic variants that predispose to Paget's disease and to determine how the causal mutations and predisposing polymorphisms interact with environmental factors to influence bone cell function and cause the focal bone lesions that are characteristic of the disease.

Paget disease of bone

Despite significant advances in management, Paget disease remains an enigmatic disorder. There are no animal models, and while its end result --a focal disorder of accelerated bone turnover--is easily recognized, the causes and evolution of the disorder remain uncertain. Recent evidence strongly implicates both genetic and environmental factors in its etiology. The authors consider some of the unresolved questions surrounding Paget disease, including the attenuating prevalence and severity of the disease; how these observations might be reconciled with an apparently highly penetrant genetic susceptibility; what the putative environmental triggers of Paget disease might be; and what relapse after treatment tells us. Most observations seem to fit best with the idea that Paget disease behaves as a multifocal benign neoplasm.

Pathogenesis and management of Paget's disease of bone

Paget's disease of bone is a common disease characterised by focal areas of increased bone turnover, affecting one or several bones throughout the skeleton. Paget's disease is often asymptomatic but can be associated with bone pain and other complications such as osteoarthritis, pathological fracture, bone deformity, deafness, and nerve compression syndromes. Genetic factors have an important role in this disease, and mutations have been identified in four genes that cause Paget's disease and related syndromes. The most important of these is Sequestosome 1 (SQSTM1), which is a scaffold protein in the nuclear factor kappaB (NFkappaB) signalling pathway. Patients with SQSTM1 mutations have severe Paget's disease of bone and a high degree of penetrance with increasing age. Environmental factors also contribute. Most research has focused on paramyxovirus infection as a possible trigger, but evidence for this notion is conflicting. Other potential triggers include deficiency of dietary calcium and repetitive mechanical loading of the skeleton. Medical management of Paget's disease of bone is based on giving inhibitors of osteoclastic bone resorption, and bisphosphonates are the treatment of first choice. Bisphosphonate therapy is primarily indicated for patients who have bone pain arising from increased metabolic activity in affected bones. Bisphosphonate therapy is highly effective at reducing bone turnover, and it has been shown to heal radiological lesions and restore normal histology; however, the long-term effects of bisphosphonates on disease progression have not been adequately studied. No firm evidence as yet exists to show that bisphosphonates can prevent the development of complications of Paget's disease of bone, and further work is needed to address the effects of treatment on long-term clinical outcome.

A review of Paget's disease of bone with a focus on the efficacy and safety of zoledronic acid 5 mg

BACKGROUND

Paget's disease of bone, the second most common metabolic bone disease in the United States, is characterized by localized areas of excessive bone resorption coupled with accelerated bone formation, resulting in new bone that is less structurally organized and is weaker than normal bone. Complications of Paget's disease can include bone pain, osteoarthritis, skeletal deformity, hearing loss, and fractures. The objective of this review is to provide a comprehensive overview of current standards of treatment in Paget's disease.

SCOPE

A review of literature from 1974 to 2007 was performed on topics such as epidemiology, etiology, treatment of Paget's disease of bone, and bisphosphonates.

FINDINGS

Paget's disease affects an estimated 2-7% of persons of age 55 years or older in North America and western Europe. Antiresorptive treatment with bisphosphonates is the standard treatment, but there may be limitations to oral therapy. Intravenous pamidronate is efficacious and has long been available, but its use is hindered by an impractical recommended dosing regimen of 30 mg IV over 4 h for three consecutive days. In two identical, double-blind, 6-month trials, 96% of patients treated with a one-time intravenous treatment of zoledronic acid 5 mg achieved therapeutic response, compared with 74% treated with 60 days of daily oral treatment with risedronate 30 mg (p < 0.001). One limitation of this review is that historical data are not reviewed in the same level of detail as newer treatments, because recent advances in pharmacotherapy of Paget's disease have reduced the clinical utility of the older drugs.

CONCLUSION

The etiology of Paget's disease is unclear, but some evidence suggests genetic and viral components. Bisphosphonates restore normal bone turnover and relieve bone pain, but oral formulations may be limited by complicated dosing regimens and poor gastrointestinal absorption. The bisphosphonate, zoledronic acid is administered as a single intravenous infusion and offers antiresorptive efficacy and longer-lasting remission.

An Italian family with inclusion-body myopathy and frontotemporal dementia due to mutation in theVCP gene

Mutations of the valosin-containing protein gene (VCP) are responsible for autosomal-dominant hereditary inclusion-body myopathy associated with frontotemporal dementia and Paget's disease of bone. We identified the p.R155C missense mutation in the VCP gene segregating in an Italian family with three affected siblings, two of whom had a progressive myopathy associated with dementia, whereas one exhibited a progressive myopathy and preclinical signs of Paget's disease of bone. Our study demonstrates that VCP mutations are found in patients of Italian background and may lead to a variable clinical phenotype even within the same kinship.

Brain imaging and neuropsychology in late-onset dementia due to a novel mutation (R93C) of valosin-containing protein

Inclusion body myopathy with Paget disease of bone and frontotemporal dementia (IBMPFD, MIM 167320) is a recently identified autosomal dominant disorder due to mutations in the valosin-containing protein (VCP) that affects muscle, bone and brain. Brain involvement and neuropsychological findings of IBMPFD have not been described in detail. A patient carried a novel heterozygous base pair change, 47832C>T, in the VCP gene that resulted in substitution of an arginine residue by cysteine at position 93 (R93C). He presented first with myopathy while bone involvement remained subclinical. The patient developed behavioral abnormalities in his 60s and showed frank personality change with fluent empty speech at the age of 74 years. This syndrome was best classified as semantic dementia. Magnetic resonance imaging disclosed slight but progressive cerebral atrophy with prominent callosal and frontal white matter loss. Positron emission tomography demonstrated glucose hypometabolism of the frontal and temporal lobes disproportionate to their structural involvement. This first comprehensive clinical and neuroimaging study in IBMPFD may raise the awareness among clinicians as well as basic scientists for this exemplary genetic model of dementia.

Delayed development of Paget's disease in offspring inheriting SQSTM1 mutations

Familial Paget's disease is associated with mutations in SQSTM1. We compared the age at diagnosis and severity of Paget's disease in parents with SQSTM1 mutations to their offspring who inherited a mutation. At any given age, the offspring were less likely to be diagnosed with Paget's disease and had less severe disease than their parents.

INTRODUCTION

Mutations in sequestosome 1 (SQSTM1) occur in 25-50% of cases of familial Paget's disease and are thought to be disease-causing. We sought to determine whether there are differences in age at diagnosis and severity of disease in parents and their offspring who share the same genetic predisposition to Paget's disease.

MATERIALS AND METHODS

Eighty-four offspring from 10 families (29 index patients with Paget's disease) with mutations in SQSTM1 were approached, and 58 agreed to participate. The ubiquitin-binding domain region of SQSTM1 was sequenced, and the presence or absence of the known mutation was established. The presence of Paget's disease in offspring who had inherited an SQSTM1 mutation was determined by bone scintigraphy and measurement of serum alkaline phosphatase (ALP).

RESULTS

Twenty-three of 58 offspring had inherited a germline mutation in SQSTM1. The mean ALP was 77 U/liter in offspring with mutations and 72 U/liter in those without mutations (p=0.84). Scintiscans from four offspring (mean age, 45 years; mean ALP, 139 U/liter; mean skeletal involvement, 6%) showed evidence of Paget's disease but were normal in the other 19 (mean age, 44 years; mean ALP, 64 U/liter). In comparison, in the 15 parents of the 23 offspring, the mean age of diagnosis was 48 years, the mean ALP was 850 U/liter, and the mean skeletal involvement was 30%. There was a 63% reduction in the risk of being diagnosed with Paget's disease at a comparable age in the offspring compared with the parents (p=0.028).

CONCLUSIONS

Only 17% of offspring inheriting an SQSTM1 mutation had evidence of Paget's disease on scintigraphy, and this was diagnosed at a later age and was less extensive than in their affected parents. SQSTM1 thus shows incomplete penetrance. The data are consistent with the hypothesis that an environmental factor is important in the pathogenesis and clinical phenotype of familial Paget's disease and that exposure to this factor may be falling.

Pathophysiology and Genetics of Metabolic Bone Disorders Characterized by Increased Bone Turnover

Bone is the most important supportive tissue in the human body, and in order to maintain its integrity, it is continuously renewed by a process called "remodeling". Paget's disease of bone (PDB), familial expansile osteolysis (FEO), expansile skeletal hyperphosphatasia (ESH), early-onset Paget's disease of bone (EOPDB), and juvenile Paget's disease (JPD) are all metabolic bone disorders characterized by accelerated bone remodeling. Histological studies have shown that bone-resorbing osteoclasts are the primary disease-causing cells in these disorders. In this review, we provide an overview of the clinical differences between diseases with increased bone turnover. Our main focus is on Paget's disease because this is, by far, the most common form of this type of disease. Molecular genetic studies of these disorders have revealed key players in bone remodeling and have provided further insights in signal transduction in osteoclasts. Moreover, a syndromal form of PDB has been characterized in which PDB is associated with inclusion body myopathy and frontotemporal dementia, pointing toward similar biological pathways in osteoclasts, muscle, and brain cells. However, several additional genes underlying conditions with increased bone turnover remain to be identified.

Contribution of genetic factors to the pathogenesis of Paget's disease of bone and related disorders

Paget's disease of bone (PDB) is a common condition with a strong genetic component that is characterized by focal increases in bone turnover, leading to bone deformity, pathological fractures, and various other complications. Several rare disorders have also been described that show phenotypic overlap with PDB. Genome-wide searches have identified several susceptibility loci for PDB and PDB-like disorders, and mutations that cause these disorders have now been identified in four genes, all of which are involved in the RANK-NF-kappaB signaling pathway. Mutations in SQSTM1, which encodes an important scaffold protein in this pathway, have been found to be a common cause of classical PDB. Thus far, all disease-causing mutations in SQSTM1 affect the ubiquitin-associated (UBA) domain of the gene product and cause loss of ubiquitin binding. The rare PDB-like disorders of familial expansile osteolysis, early-onset familial PDB, and expansile skeletal hyperphosphatasia are caused by duplication mutations in exon 1 of the TNFRSF11A gene, which encodes the RANK receptor. This gene does not seem to be involved in the pathogenesis of classical PDB. Inactivating mutations in the TNFRSF11B gene, which encodes osteoprotegerin, cause juvenile PDB, and TNFRSF11B polymorphisms seem to increase the risk of classical PDB. The rare syndrome of hereditary inclusion body myopathy, PDB, and frontotemporal dementia (IBMPFD) is caused by mutations in the VCP gene, which is involved in regulating I-kappaB degradation by the proteasome. The disease-causing mutations in VCP cluster in and around a domain involved in ubiquitin binding. Whereas SQSTM1 has emerged as an important gene for classical PDB, most kindreds with familial PDB do not carry SQSTM1 mutations, indicating that additional genes for PDB remain to be discovered. In light of the molecular defects that have been identified thus far, it seems likely that these genes will also be involved in the RANK-NF-kappaB signaling pathway or its interactions with the ubiquitin-proteasome system.

Biochemical assessment of Paget's disease of bone

Biochemical measurements of bone turnover provide an objective assessment of disease activity and the response to treatment. Alkaline phosphatase is the best characterized of the bone turnover markers and reflects the extent and activity of Paget's disease. However, in addition to bone-specific alkaline phosphatase (Bone ALP), there is also osteocalcin (OC) and procollagen type 1 N-terminal propeptide (P1NP) as formation markers. A variety of telopeptides (C-terminal telopeptide of type I collagen, [CTX], N-telopeptide of type I collagen [NTX]) or cross-link breakdown products of type 1 collagen can be used to assess bone resorption. Total alkaline phosphatase (Total ALP), Bone ALP, and P1NP all perform similarly in diagnosis and in evaluating the response to treatment, but the general availability, low interassay variation, and inexpensiveness of Total ALP makes it the best test for routine use. Measurement of the biological variability of the different markers in stable, untreated Paget's disease indicates how great a change (critical difference) is needed to define a true alteration in disease activity. Bone ALP, P1NP, and NTX show the highest therapy induced change/critical difference ratio during antiresorptive treatment. Some of the resorption markers show more complex changes in response to treatment. Pyridinoline (PYD) or deoxypyridinoline (DPD) cross-links of type 1 collagen are excreted in urine either as free or as peptide bound moieties, but it is the latter which decrease by the greatest amount in response to bisphosphonate therapy. Newly formed type 1 collagen contains an aspartyl-glycine motif (alphaCTX), which undergoes spontaneous isoaspartyl formation to betaCTX as the bone ages. In untreated Paget's disease, the alphaCTX is raised proportionately more (16-fold) than betaCTX (3-fold) and decreases in response to bisphosphonate therapy to a greater extent than betaCTX (measured in the sCTX assay). As bisphosphonates have become more potent, the aim of treatment has shifted toward the achievement of a rate of bone turnover in the lower part of the reference range. This is important because the duration of remission of disease activity is strongly determined by the post treatment nadir bone turnover.

Surgical management of Paget's disease of bone

Paget's disease is a chronic nonmetabolic bone disorder that is characterized by increased bone resorption, bone formation, and remodeling. This unbalanced process may lead to osseous deformities, structural weakness, and altered joint biomechanics, all of which can make surgical reconstruction difficult. Although few patients with Paget's disease ever need surgical treatment, successful surgical management of orthopedic manifestations of the disease has improved the quality of life for these patients. Surgical options include corrective osteotomy for long bone deformity, fracture fixation, joint arthroplasty, spinal decompression, and tumor resection. Patients are at increased risk for surgical complications such as blood loss and heterotopic bone formation. Issues relating to the surgical management of patients with Paget's disease such as appropriate preoperative diagnosis, technical challenges of surgery, and strategies to improve the long-term outcome of surgical intervention are discussed.

Surgical manifestations of Paget's disease

Paget's disease is a chronic, nonmetabolic bone disorder characterized by increased bone resorption, bone formation, and remodeling. This unbalanced process may lead to osseous deformities, structural weakness, and altered joint biomechanics, all of which can make surgical reconstruction difficult. Although few patients with Paget's disease require surgical treatment, successful surgical management of severe orthopaedic complications has improved the quality of life for these patients. Surgical options include osteotomy to correct long-bone deformity and arthroplasty to restore altered joint mechanics. Patients are at increased risk for surgical complications, such as blood loss and heterotopic bone formation. Issues relating to the surgical management of patients with Paget's disease include appropriate preoperative diagnosis, technical challenges of surgery, and strategies to improve the long-term outcome of surgical intervention.

Does Paget's disease exist in India?: A series of 21 patients

OBJECTIVE

Paget's disease of bone has been described as a few case reports from India. The aim of the present study is to document the existence of Paget's disease (PD) in India.

MATERIAL AND METHODS

We describe demography, clinical manifestations, biochemical and radiological profile and the treatment outcome of 21 patients of PD.

RESULTS

Mean (+/-SD) age of these patients at presentation was 49.2 +/- 17.6 years and the male to female ratio was 2.5:1. Common clinical manifestations included backache, headache and bone pains. Others were fracture, joint pain, deafness, gait ataxia, visual impairment and difficulty in biting. Two patients presented with hydrocephalus and one had recurrent paraparesis. Fifteen (71.4%) patients had polyostotic and six (28.6%) had monoostotic Paget's disease. More commonly involved bones were skull and spine (61.9%) followed by pelvis (38.1%), femur (33.3%), tibia (9%) and ulna (9%). Mean (+/-SD) serum alkaline phosphatase at diagnosis was 1514 +/- 1168 IU/L and nine months after treatment with bisphosphonates decreased to 454 +/- 406 IU/ L(P<0.03).

CONCLUSION

This illustrates that Paget's disease does exist in India and a high index of suspicion is required to clinch the diagnosis.

Protocol for stage 1 of the GaP study (Genetic testing acceptability for Paget's disease of bone): an interview study about genetic testing and preventive treatment: would relatives of people with Paget's disease want testing and treatment if they were available?

BACKGROUND

Paget's disease of bone (PDB) is characterised by focal increases in bone turnover, affecting one or more bones throughout the skeleton. This disrupts normal bone architecture and causes pain, deformity, deafness, osteoarthritis, and fractures. Genetic factors are recognised to play a role in PDB and it is now possible to carry out genetic tests for research. In view of this, it is timely to investigate the clinical potential for a programme of genetic testing and preventative treatment for people who have a family history of PDB, to prevent or delay the development of PDB. Evidence from non-genetic conditions, that have effective treatments, demonstrates that patients' beliefs may affect the acceptability and uptake of treatment. Two groups of beliefs (illness and treatment representations) are likely to be influential. Illness representations describe how people see their illness, as outlined in Leventhal's Self-Regulation Model. Treatment representations describe how people perceive potential treatment for their disease. People offered a programme of genetic testing and treatment will develop their own treatment representations based on what is offered, but the beliefs rather than the objective programme of treatment are likely to determine their willingness to participate. The Theory of Planned Behaviour is a theoretical model that predicts behaviours from people's beliefs about the consequences, social pressures and perceived control over the behaviour, including uptake of treatment.

METHODS/DESIGN

This study aims to examine the acceptability of genetic testing, followed by preventative treatment, to relatives of people with PDB. We aim to interview people with Paget's disease, and their families, from the UK. Our research questions are:1. What do individuals with Paget's disease think would influence the involvement of their relatives in a programme of genetic testing and preventative treatment? What do relatives of Paget's disease sufferers think would influence them in accepting an offer of a programme of genetic testing and preventative treatment?

DISCUSSION

Our research will be informed by relevant psychological theory: primarily the Self-Regulation Model and the Theory of Planned Behaviour. The results of these interviews will inform the development of a separate questionnaire-based study to explore these research questions in greater detail.

Loss of ubiquitin binding is a unifying mechanism by which mutations of SQSTM1 cause Paget's disease of bone

Ubiquitin-associated (UBA) domain mutations of SQSTM1 are an important cause of Paget's disease of bone (PDB), which is a human skeletal disorder characterized by abnormal bone turnover. We previously showed that, when introduced into the full-length SQSTM1 protein, the disease-causing P392L, M404V, G411S, and G425R missense mutations and the E396X truncating mutation (representative of all of the SQSTM1 truncating mutations) cause a generalized loss of monoubiquitin binding and impaired K48-linked polyubiquitin binding at physiological temperature. Here, we show that the remaining three known PDB missense mutations, P387L, S399P, and M404T, have similar deleterious effects on monoubiquitin binding and K48-linked polyubiquitin binding by SQSTM1. The P387L mutation affects an apparently unstructured region at the N terminus of the UBA domain, some five residues from the start of the first helix, which is dispensable for polyubiquitin binding by the isolated UBA domain. Our findings support the proposal that the disease mechanism in PDB with SQSTM1 mutations involves a common loss of ubiquitin binding function of SQSTM1 and implicate a sequence extrinsic to the compact globular region of the UBA domain as a critical determinant of ubiquitin recognition by the full-length SQSTM1 protein.

Paget’s disease and cochlear implantation

Paget’s disease of bone is a common disorder of unresolved etiology characterized by excessive bone resorption followed by excessive bone formation. If the skull isaffected this may result in hearing loss and eventually develop into profound deafness. To date, no cases of cochlear implantation in patients with Paget’s disease have been reported.

The authors present a case of radiographically confirmed Paget’s disease of the skull in a 77-year-old man with a 20-year history of progressive bilateral sensorineural hearing losswho underwent cochlear implantation. A successful insertion of the Nucleus 24 Contour electrodearray was achieved without surgical and postoperative complications.

At the 10 months’ postoperative evaluation, the patient had gained useful open-set speech perception. In quiet conditions, his performance scores on the word and sentence recognition tests were 100 and 98 per cent, respectively. In the presence of noise (at +10 dB. signal-to-noise ratio), his performance scores on the word and sentence recognition tests were 96 and 94per cent, respectively.

Genetics of Paget's disease of bone

Paget's disease of bone is a chronic bone disease that affects up to 3% of Caucasians older than 55 years. The cause of Paget's disease is unknown but involves genetic factors. Familial cases display an autosomal dominant pattern of inheritance with incomplete penetrance. Genetic heterogeneity has been demonstrated and eight potential susceptibility loci identified. There is sound evidence incriminating Sequestosome 1 (SQSTM1) on the long arm of chromosome 5 (5q35-qter), of which nine mutations have been described in Paget's disease of bone. These mutations are located in exons 7 and 8, which encode a highly conserved ubiquitin-binding domain. The prevalence of SQSTM1 mutations is about 10% in France. Tests for SQSTM1 mutations should be done in patients with Paget's disease of bone, even where the family history is negative. Detection of a mutation allows evaluation of family members to ensure early diagnosis of the disease before complications develop.

Prevalence and clinical features of Paget's disease of bone in Japan

The present study aimed to evaluate the prevalence and clinical presentation of Paget's disease of bone (PDB) in Japan. As PDB is a very rare disease in Japan, a nationwide mail survey was conducted targeting doctors in the specialty most frequently diagnosing and treating PDB patients in Japan. First, the literature for all case reports in Japan published between January 1990 and December 2002 was reviewed to determine who was diagnosing and treating PDB in Japan. This literature review for all case reports in Japan revealed that 72.1% of cases in Japan were reported from departments of orthopedic surgery. A nationwide two-phase mail survey was conducted for the departments of orthopedic surgery of 2,320 general hospitals accredited by the Japanese Orthopaedic Association. Phase 1 involved determining how many patients with PDB were followed at each hospital. If the answer was one or more, phase 2 of the survey gathered information on the clinical presentation of current patients. The mail survey yielded a final response rate of 75.4% for phase 1 and 87.6% for phase 2. Phase 1 indicated that the prevalence of PDB in Japan is about 2.8 cases per million capita. Phase 2 revealed a slight female predominance, lower frequency of familial clustering, higher frequency of femoral fracture in the affected femur, and a higher ratio of symptomatic PDB in Japan compared with findings in countries displaying a higher prevalence of PDB. The present epidemiological study revealed that the disorder is extremely rare in Japanese individuals, and that some differences exist with regard to the clinical features of PDB between Japanese patients and patients from high-prevalence countries.

Inclusion body myopathy and Paget disease is linked to a novel mutation in the VCP gene

Mutations in the valosin-containing protein (VCP) on chromosome 9p13-p12 were recently found to be associated with hereditary inclusion body myopathy, Paget disease of the bone, and frontotemporal dementia (IBMPFD). We identified a novel missense mutation in the VCP gene (R159H; 688G>A) segregating with this disease in an Austrian family of four affected siblings, who exhibited progressive proximal myopathy and Paget disease of the bone but without clinical signs of dementia.

Maladie de Paget, exploration et surveillance

Paget's disease is a progressive bone disease, characterized by bone hypertrophy and increased bone resorption. The pain and deformity that characterize its clinical course are not simple to assess, but it has a characteristic radiographic appearance. In most cases, treatment can be monitored through biological markers of bone turnover. Total alkaline phosphatase is the best marker and measurement of collagen breakdown products is useful in difficult cases. The goal of treatment is the normalization of these biological markers, to prevent complications of the disease.

Paget disease of bone

Paget disease of bone (PD) is characterized by excessive bone resorption in focal areas followed by abundant new bone formation, with eventual replacement of the normal bone marrow by vascular and fibrous tissue. The etiology of PD is not well understood, but one PD-linked gene and several other susceptibility loci have been identified, and paramyxoviral gene products have been detected in pagetic osteoclasts. In this review, the pathophysiology of PD and evidence for both a genetic and a viral etiology for PD will be discussed.

Interaction between osteoblast and osteoclast: impact in bone disease

The intercellular communication between osteoblasts and osteoclasts is crucial to bone homeostasis. Since Rodan and Martin proposed the control of osteoclasts by osteoblasts in the 1980s, many factors have been isolated from osteoblasts and shown to regulate the differentiation and function of osteoclasts. However, the mechanism by which osteoblasts regulate osteoclasts during bone remodelling is still unclear. On the other hand, it is well accepted that many metabolic bone diseases are associated with the disruption of the communication between osteoblast and osteoclasts. Thus, this review focuses on the cross-talk between osteoblasts and osteoclasts and its impact in bone disease.