Archaeological skeletons support a northwest European origin for Paget's disease of bone

The Decline of Paget's Disease of Bone and Domestic Coal Use-A Hypothesis

The cause of Paget's disease of bone (PDB) is unknown. It emerged as a distinct entity in Britain in the late nineteenth century when it was prevalent, and florid presentation not uncommon. Epidemiological surveys in the 1970s showed that Britain had a substantially higher prevalence of PDB than any other country. Studies in the late twentieth and early twenty-first centuries have documented an unexplained change in presentation, with a greatly reduced prevalence and less severe disease than formerly. The emergence of PDB in Britain coincided with rapid industrialization which, in turn, was driven by the use of coal for energy. In the home, bituminous coal was customarily burnt on an open hearth for heating. Using data on coal production, population size, and estimates of domestic use, the estimated exposure to domestic coal burning rose threefold in Britain during the nineteenth century and began to fall after 1900. This pattern fits well with the decline in PDB documented from death certification and prevalence surveys. Colonists moving from Britain to North America, Australia and New Zealand established coal mines and also used coal for domestic heating. PDB was found in these settler populations, but was largely absent from people indigenous to these lands. In all parts of the world PDB prevalence has fallen as the burning of coal in open hearths for domestic heating has reduced. The nature of the putative factor in coal that could initiate PDB is unknown, but possible candidates include both organic and inorganic constituents of bituminous coal.

The various meanings and uses of bone "remodeling" in biological anthropology: A review

OBJECTIVES

In modern bone biology, the term "remodeling" generally refers to internal bone turnover that creates secondary osteons. However, it is also widely used by skeletal biologists, including biological anthropologists as a catch-all term to refer to different skeletal changes. In this review, we investigated how "remodeling" is used across topics on skeletal biology in biological anthropology to demonstrate potential problems with such pervasive use of a generalized term.

METHODS

Using PubMed and Google Scholar, we selected and reviewed 205 articles that use the term remodeling to describe skeletal processes and have anthropological implications. Nine edited volumes were also reviewed as examples of collaborative work by different experts to demonstrate the diverse and extensive use of the term remodeling.

RESULTS

Four general meanings of bone "remodeling" were identified, namely, internal turnover, functional adaptation, fracture repair, and growth remodeling. Additionally, remodeling is also used to refer to a broad array of pathological skeletal changes.

DISCUSSION

Although we initially identified four general meanings of bone remodeling, they are not mutually exclusive and often occur in combination. The term "remodeling" has become an extensively used catch-all term to refer to different processes and outcomes of skeletal changes, which inevitably lead to misunderstanding and a loss of information. Such ambiguity and confusion are potentially problematic as the field of biological anthropology becomes increasingly multidisciplinary. Therefore, we advocate for precise, context-specific definitions and explanations of bone remodeling as it continues to be used across disciplines within and beyond biological anthropology.

[Paget's disease of bone: 1877-2023. Etiology, and management of a disease on epidemiologic transition]

Paget's disease of bone is characterized by the alteration, in one or several bone locations, of the equilibrium between bone formation and bone resorption. This imbalance results in a disorganized, widened bone, in many cases with increased bone density, although more fragile. A genetic predisposition for Paget's disease of bone could explain between 5% and 40% of the cases. Different environmental factors should explain the rest of the cases. Paget's disease of bone was classically considered the second most common metabolic bone disease. However, in recent decades there has been a marked decrease in both incidence and clinical severity. These changes have led to believe that the influence of some environmental factor may have diminished or even disappeared. This decrease in incidence should not be an excuse for abandoning Paget's disease of bone research, but rather it should be the reason to remain searching to try to understand better its pathogenesis.

Updates on Paget's Disease of Bone

Paget's disease of the bone is a prevalent bone disease characterized by disorganized bone remodeling; however, it is comparatively uncommon in East Asian countries, including China, Japan, and Korea. The exact cause still remains unknown. In genetically susceptible individuals, environmental triggers such as paramyxoviral infections are likely to cause the disease. Increased osteoclast activity results in increased bone resorption, which attracts osteoblasts and generates new bone matrix. Fast bone resorption and formation lead to the development of disorganized bone tissue. Increasing serum alkaline phosphatase or unique radiographic lesions may serve as the diagnostic indicators. Common symptoms include bone pain, bowing of the long bones, an enlarged skull, and hearing loss. The diagnosis is frequently confirmed by radiographic and nuclear scintigraphy of the bone. Further, bisphosphonates such as zoledronic acid and pamidronate are effective for its treatment. Moreover, biochemical monitoring is superior to the symptoms as a recurrence indicator. This article discusses the updates of Paget's disease of bone with a clinical case.

The potential for over diagnosis of Paget's disease of bone using macroscopic analysis

OBJECTIVE

This study explores the validity of Paget's disease of bone (PDB) reported in unpublished skeletal reports, based on macroscopic analysis alone.

MATERIALS

The high prevalence of 'suspected' Paget's disease (10.7%) in an early modern sample from St John's the Evangelist Church in Redhill, Surrey is reassessed.

METHODS

Signs of PDB were examined in 53 well-preserved adults aged 35 + years using macroscopic, radiographic and histological techniques.

RESULTS

Macroscopic features of PDB were identified in 8 individuals (15%), with 5 individuals later rejected using radiography. Two individuals showed classic radiographic features of PDB, with a third presenting possible features in radiography (5.7%). These three cases were confirmed by histological analysis.

CONCLUSIONS

PDB should not be suggested as a single diagnosis in cases of bone hypertrophy without confirmation using radiography.

SIGNIFICANCE

The growing popularity of 'big data' projects and limited collections access means that unpublished cases of PDB are often included in large scale analyses, impacting our understanding of the evolution of this disease. Using macroscopic analysis alone leads to overdiagnosis. Histological analysis is unnecessary when radiographic features are present, but provides a useful diagnostic step in long bones in advanced cases of PBD.

LIMITATIONS

The radiographic sample in this study was limited to three individuals.

SUGGESTIONS FOR FURTHER RESEARCH

The conclusion that radiography alone can be used to identify PDB in archaeological cases merits further research on a larger number of cases.

Paget's Disease of Bone: Osteoimmunology and Osteoclast Pathology

PURPOSE OF REVIEW

The purpose of this review is to recognize clinical features of Paget's disease of bone and to describe how the osteoclast, a myeloid-derived cell responsible for bone resorption, contributes to the disease.

RECENT FINDINGS

Recent studies have identified several variants in SQSTM1, OPTN, and other genes that may predispose individuals to Paget's disease of bone; studies of these genes and their protein products have elucidated new roles for these proteins in bone physiology. Understanding the pathologic mechanisms in the Pagetic osteoclast may lead to the identification of future treatment targets for other inflammatory and autoimmune diseases characterized by abnormal bone erosion and/or osteoclast activation.

The Skinner Burial of Ontario, Canada, and the Question of Paget's Disease in the Americas

PURPOSE

To examine a possible case of Paget's disease of bone (PDB) in an Indigenous pre-contact male from Canada, individual D of the Skinner site in Ontario.

METHODS

Radiographs, CT scan and histological analysis.

RESULTS

The histological analysis revealed the mosaic pattern that characterizes PDB. CT scans show advanced sclerosis of the cranium and a diminished diplӧe with osteolytic lesions.

CONCLUSIONS

The pathological features that have been identified are collectively characteristic of PDB.

SIGNIFICANCE

The Skinner case advances our understanding of the global history and distribution of PDB.

LIMITATIONS OF STUDY

Only two New World cases have been identified and neither has been studied in sufficient detail.

SUGGESTIONS FOR FUTURE RESEARCH

The older individuals in precolonial New World skeletal series should be given CT scans, which are non-intrusive, to be followed by histological and genetic analyses when indicated.

Molecular insights into an ancient form of Paget's disease of bone

We identify an ancient and atypical form of Paget’s disease of bone (PDB) in a collection of medieval skeletons exhibiting unusually extensive pathological changes, high disease prevalence, and low age-at-death estimations. Proteomic analysis of ancient bone-preserved proteins combined with analysis of small RNAs supports a retrospective diagnosis of PDB. Remains affected by other skeletal disorders may therefore hold a chemical memory amenable to similar molecular interrogation. Abnormalities in a contemporary PDB-linked protein detected in ancient tooth samples indicate that dentition may represent an unexplored storehouse for the study of skeletal disorders. Our work provides insights into the natural history of PDB and prompts a similar revaluation of other archaeological collections.

Paget’s disease of bone (PDB) is a chronic skeletal disorder that can affect one or several bones in individuals older than 55 y of age. PDB-like changes have been reported in archaeological remains as old as Roman, although accurate diagnosis and natural history of the disease is lacking. Six skeletons from a collection of 130 excavated at Norton Priory in the North West of England, which dates to medieval times, show atypical and extensive pathological changes resembling contemporary PDB affecting as many as 75% of individual skeletons. Disease prevalence in the remaining collection is high, at least 16% of adults, with age at death estimations as low as 35 y. Despite these atypical features, paleoproteomic analysis identified sequestosome 1 (SQSTM1) or p62, a protein central to the pathological milieu of PDB, as one of the few noncollagenous human sequences preserved in skeletal samples. Targeted proteomic analysis detected >60% of the ancient p62 primary sequence, with Western blotting indicating p62 abnormalities, including in dentition. Direct sequencing of ancient DNA excluded contemporary PDB-associated SQSTM1 mutations. Our observations indicate that the ancient p62 protein is likely modified within its C-terminal ubiquitin-associated domain. Ancient miRNAs were remarkably preserved in an osteosarcoma from a skeleton with extensive disease, with miR-16 expression consistent with that reported in contemporary PDB-associated bone tumors. Our work displays the use of proteomics to inform diagnosis of ancient diseases such as atypical PDB, which has unusual features presumably potentiated by yet-unidentified environmental or genetic factors.

Diagnosis and Management of Paget's Disease of Bone in Adults: A Clinical Guideline

An evidence-based clinical guideline for the diagnosis and management of Paget's disease of bone (PDB) was developed using GRADE methodology, by a Guideline Development Group (GDG) led by the Paget's Association (UK). A systematic review of diagnostic tests and pharmacological and nonpharmacological treatment options was conducted that sought to address several key questions of clinical relevance. Twelve recommendations and five conditional recommendations were made, but there was insufficient evidence to address eight of the questions posed. The following recommendations were identified as the most important: 1) Radionuclide bone scans, in addition to targeted radiographs, are recommended as a means of fully and accurately defining the extent of metabolically active disease in patients with PDB. 2) Serum total alkaline phosphatase (ALP) is recommended as a first-line biochemical screening test in combination with liver function tests in screening for the presence of metabolically active PDB. 3) Bisphosphonates are recommended for the treatment of bone pain associated with PDB. Zoledronic acid is recommended as the bisphosphonate most likely to give a favorable pain response. 4) Treatment aimed at improving symptoms is recommended over a treat-to-target strategy aimed at normalizing total ALP in PDB. 5) Total hip or knee replacements are recommended for patients with PDB who develop osteoarthritis in whom medical treatment is inadequate. There is insufficient information to recommend one type of surgical approach over another. The guideline was endorsed by the European Calcified Tissues Society, the International Osteoporosis Foundation, the American Society of Bone and Mineral Research, the Bone Research Society (UK), and the British Geriatric Society. The GDG noted that there had been a lack of research on patient-focused clinical outcomes in PDB and identified several areas where further research was needed. © 2019 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

A microscopic evaluation of Paget's disease of bone from a Byzantine monastic crypt in Jordan

Paget's disease of bone (PDB) is a metabolic bone disease that has been present in human populations for over 2000 years, with the earliest cases reported in Western Europe. Now present globally, PDB is one of the most common metabolic bone diseases in modern populations. This study details possible PDB of an adult male (MNR-EN Skull 3) with abnormally thickened cranial bones (17 mm). The skull was recovered from commingled skeletal remains excavated from the Robebus crypt at the Byzantine monastery of Mount Nebo, Jordan (c. late 4-7^th C). Micro-CT imaging and histological sections of the bone samples revealed an abnormal pattern of bone remodeling, with atypical osteon formation, convoluted and enlarged trabeculae, and an overall pattern of highly vascularized bone. Polarized microscopy produced a mix of woven bone and lamellar bone, the mosaic pattern of atypical bone remodeling indicative of PDB. Coupled with the dense, thickened nature of the vault bones, these data suggest that the individual had PDB. To our knowledge, this represents the earliest evidence of PDB in the Middle East supported by micro-analysis, and adds to the emerging paleopathological literature involving commingled skeletal remains and the potential for identifying unique disease processes.

A case of Paget from a Northern Italy medieval necropolis

An excavation conducted in 2002 by the Lombardy Archaeological Heritage in the St. Giulio Church (Cassano Magnago-Northern Italy) revealed an adult skeleton with an important alteration of the left femur. The femur, longer than the contralateral, exhibited an expansion of the full diaphysis; the surface was coarsened and porous. In cross section, it appeared that almost all the cortical bone had been converted into cancellous bone. Macroscopic and radiological alterations are suggestive of the monostotic form of Paget's disease, a chronic disorder, characterized by focal areas of excessive osteoclastic bone resorption followed by a secondary increase in osteoblastic bone formation. Differential diagnosis is complex for Paget's disease, requiring histological analysis, which revealed a thickened and disorganized trabecular pattern with thick cement lines. Such features, resembling to a mosaic pattern, are typical of Paget's disease.

Paget's disease of bone

Paget's disease is a chronic focal high turnover bone disorder that is primarily present in middle-aged or older adults. It seems to be restricted to humans and has no clear parallels with other diseases. Although much has been learnt about its pathology and epidemiology, and treatment is now highly effective we still lack a complete understanding of its etiology and biology. This review focusses on the natural history of the disorder, in particular its changing epidemiology, recent discoveries about its genetic basis and current approaches to diagnosis and treatment. While there is strong evidence for genetic predisposition to Paget's disease, there is also compelling evidence that it is becoming less prevalent, the age of patients at presentation is increasing and that the extent of skeletal involvement is diminishing, implying that there is an important, but as yet unidentified, environmental factor in its etiology. Contemporary patients are typically elderly and have few bones involved. Treatment with potent intravenous bisphosphonates provides prolonged remission and many will require only once in a lifetime treatment.

The Changing Presentation of Paget's Disease of Bone in Australia, A High Prevalence Region

Studies from several countries suggest that the incidence of Paget's disease of bone (PDB) and the severity of newly diagnosed cases are declining. The aim of this study was to examine secular changes in clinical presentation of PDB in Australia, which historically had the highest prevalence outside the United Kingdom. The participants were 293 patients (61% male) diagnosed between 1956 and 2013 with details recorded in the database of the Paget's Disease Research Group of Western Australia. The mean age at diagnosis was 62 years (range 28-90); 26% of participants had a family history of PDB and 11% had Sequestosome 1 (SQSTM1) mutations. After adjustment for covariates (SQSTM1 mutation status, family history, country of birth, smoking and dog exposure), there was a significant positive relationship between year of diagnosis and age at diagnosis (P < 0.001) and significant negative relationships between year of diagnosis and both pre-treatment total plasma alkaline phosphatase activity (ALP) and number of involved bones (P < 0.001 for each). Patients with SQSTM1 mutations had more extensive disease (P < 0.001) and higher pre-treatment ALP (P = 0.013). In subgroup analyses, relationships between year of diagnosis and each of age at diagnosis, number of involved bones and ALP were similar in patients with sporadic or familial disease, and in patients with and without SQSTM1 mutations. We conclude that the severity of PDB in Western Australia has declined over recent decades. This is likely to reflect altered exposure to one or more environmental agents involved in pathogenesis.

The Implications of the Sequestosome 1 Mutation P392L in Patients with Paget's Disease in a United States Cohort

Paget's disease of bone (PDB) is associated with a germline mutation in Sequestosome1/p62 (SQSTM1) found in ≤16 % of sporadic cases worldwide, and in 19-46 % of those studied with familial PDB. The P392L is the most prevalent mutation identified to date. This mutation by itself does not confer PDB or define the phenotype of PDB in a given person. Environmental determinants remain elusive, although increasing age of the individual, other gene polymorphisms in the context of SQSTM1 mutations, and measles virus have been implicated. Measles exposure has been unexamined in this context. The goal of this study is to compare the background history and phenotype of patients with PDB carrying the SQSTM1 P392L mutation to those patients without. Focusing on age, ancestry, P329L mutation, family history, measles exposure, distribution of PDB, and age of onset, we examined outcomes at 10 years. We postulated that aging may play a role in defining phenotype, and that this may become more visible in a well-characterized cohort. This is an observational study focused on a cohort of patients with PDB drawn from the New England Registry in whom environmental and family history has been catalogued, linked to radiographic data. Of the 217 persons who were enrolled in the Registry, 42 (19 %) responded to a letter inviting them to participate in testing for the presence of the measles antibody, and in genetic testing for the P392L mutation. The mean age of the cohort in 2001 was 70 years (range 55-79); 27 were men (64 %). The measles antibody was found in all cases tested. Nine patients had the P392L mutation (21 %), 2 with familial PDB. In these persons, early diagnosis of disease and spinal stenosis marked the male phenotype only. European ancestry was noted in the minority of those with P392L mutation. Most deaths recorded occurred in the ninth decade of life or later. Spinal stenosis emerges as a prominent phenotype in SQSTM1 P392L-positive men with aging. In these 42 patients with PDB from the New England Registry, most do not carry the SQSTM1 P392L mutation, and many do not have European ancestry. Exposure to measles was confirmed in the majority.

Paget's Disease of Bone: Approach to Its Historical Origins

Paget's disease of bone is the second most common bone disease after osteoporosis. It is characterized by focal regions of highly exaggerated bone remodeling, with abnormalities in all phases of the remodeling process. This study aims to investigate the hypothesis of a possible British origin of Paget's disease of bone by studying the worldwide geographic distribution of cases identified in ancient skeletons excavated from archaeological sites. The methodology consists in reviewing cases of Paget's disease of bone described in the literature.

Genetics of Paget's disease of bone

Paget's disease of bone (PDB) is a common metabolic bone disease characterised by focal areas of increased bone turnover, which primarily affects people over the age of 55 years. Genetic factors have a fundamental role in the pathogenesis of PDB and are probably the main predisposing factor for the disease. The genetic contribution to PDB susceptibility ranges from rare pathogenic mutations in the single gene SQSTM1 to more common, small effect variants in at least seven genetic loci that predispose to the disease. These loci have additive effects on disease susceptibility and interact with SQSTM1 mutations to affect disease severity, making them a potentially useful tool in predicting disease risk and complication and in managing treatments. Many of these loci harbour genes that have important function in osteoclast differentiation such as CSF1, DCSTAMP and TNFRSF11A. Other susceptibility loci have highlighted new molecular pathways that have not been previously implicated in regulation of bone metabolism such as OPTN, which was recently found to negatively regulate osteoclast differentiation. PDB-susceptibility variants exert their effect either by affecting the protein coding sequence such as variants found in SQSTM1 and RIN3 or by influencing gene expression such as those found in OPTN and DCSTAMP. Epidemiological studies indicate that environmental triggers also have a key role in PDB and interact with genetic factors to influence manifestation and severity of the disease; however, further studies are needed to identify these triggers.

Paget Disease of Bone

The current understanding of Paget disease of bone (PDB) has vastly changed since Paget described the first case in 1877. Medical management of this condition remains the mainstay of treatment. Surgical intervention is usually only used in fractures through pagetic bone, need for realignment to correct deformity in major long bones, prophylactic treatment of impending fractures, joint arthroplasty in severe arthritis, or spinal decompression in cases of bony compression of neural elements. Advances in surgical technique have allowed early return to function and mobilization. Despite medical and surgical intervention, a small subset of patients with PDB develops Paget sarcoma.

Genetics of Paget's disease of bone

Paget's disease of bone (PDB) is a common condition, which is characterised by focal areas of increased and disorganized bone remodeling. Genetic factors play an important role in the disease. In some cases, Paget's disease is inherited in an autosomal dominant manner and the most common cause for this is a mutation in the SQSTM1 gene. Other familial cases have been linked to the OPTN locus on Chromosome 10p13 and still other variants have been identified by genome wide association studies that lie within or close to genes that play roles in osteoclast differentiation and function. Mutations in TNFRSF11A, TNFRSF11B and VCP have been identified in rare syndromes with PDB-like features. These advances have improved understanding of bone biology and the causes of PDB. The identification of genetic markers for PDB also raises the prospect that genetic profiling could identify patients at high risk of developing complications, permitting enhanced surveillance and early therapeutic intervention.

New insights into the role of sequestosome 1/p62 mutant proteins in the pathogenesis of Paget's disease of bone

Paget's disease of bone (PDB) is characterized by focal areas of aberrant and excessive bone turnover, specifically increased bone resorption and disorganized bone formation. Germline mutations in the sequestosome 1/p62 (SQSTM1/p62) gene are common in PDB patients, with most mutations affecting the ubiquitin-associated domain of the protein. In vitro, osteoclast precursor cells expressing PDB-mutant SQSTM1/p62 protein are associated with increases in nuclear factor κB activation, osteoclast differentiation, and bone resorption. Although the precise mechanisms by which SQSTM1/p62 mutations contribute to disease pathogenesis and progression are not well defined, it is apparent that as well as affecting nuclear factor κB signaling, SQSTM1/p62 is a master regulator of ubiquitinated protein turnover via autophagy and the ubiquitin-proteasome system. Additional roles for SQSTM1/p62 in the oxidative stress-induced Keap1/Nrf2 pathway and in caspase-mediated apoptosis that were recently reported are potentially relevant to the pathogenesis of PDB. Thus, SQSTM1/p62 may serve as a molecular link or switch between autophagy, apoptosis, and cell survival signaling. The purpose of this review is to outline recent advances in understanding of the multiple pathophysiological roles of SQSTM1/p62 protein, with particular emphasis on their relationship to PDB, including challenges associated with translating SQSTM1/p62 research into clinical diagnosis and treatment.

Pathogenesis of Paget disease of bone

Paget disease of bone (PDB) is a common disease characterized by focal areas of increased and disorganized bone turnover. Some patients are asymptomatic, whereas others develop complications such as pain, osteoarthritis, fracture, deformity, deafness, and nerve compression syndromes. PDB is primarily caused by dysregulation of osteoclast differentiation and function, and there is increasing evidence that this is due, in part, to genetic factors. One of the most important predisposing genes is SQSTM1, which harbors mutations that cause osteoclast activation in 5-20 % of PDB patients. Seven additional susceptibility loci for PDB have been identified by genomewide association studies on chromosomes 1p13, 7q33, 8q22, 10p13, 14q32, 15q24, and 18q21. Although the causal variants remain to be discovered, three of these loci contain CSF1, TNFRSF11A, and TM7SF4, genes that are known to play a critical role in osteoclast differentiation and function. Environmental factors are also important in the pathogenesis of PDB, as reflected by the fact that in many countries the disease has become less common and less severe over recent years. The most widely studied environmental trigger is paramyxovirus infection, but attempts to detect viral transcripts in tissues from patients with PDB have yielded mixed results. Although our understanding of the pathophysiology of PDB has advanced tremendously over the past 10 years, many questions remain unanswered, such as the mechanisms responsible for the focal nature of the disease and the recent changes in prevalence and severity.

Paget's disease in patients of Asian descent in New Zealand

Paget's disease is considered to be uncommon in Asian people, but we have noted a recent increase in the number of Asian patients referred to our clinic, on a background of an apparently decreasing prevalence in the population of European descent. In this article, we report clinical and epidemiological features of patients of Asian descent with Paget's disease, referred between 1973 and 2010 to the Auckland Paget's disease clinic. No Asian patients were referred before 1993, but 14 have presented between 1993 and 2010, with a median of 8 years between arrival into New Zealand and time of diagnosis. The patients were predominantly of south Asian origin. None of the 8 patients tested carried a mutation in exon 8 of the sequestosome 1 (SQSTM1) gene. The number of new Paget's disease referrals expressed as a proportion of the potentially at-risk Asian population in the Auckland region (derived from census data) was 1/10(4) in 2006 to 2011. Amongst Europeans, the corresponding value decreased from 10/10(4) in 1986 to 1991 to 2/10(4) in 2006 to 2010. The increased number of people of Asian descent diagnosed with Paget's disease in the Auckland region has paralleled the increasing size of the local Asian population. The continuing decline of Paget's disease in the European population, in conjunction with the emergence of the disease in the Asian population, supports the view that an environmental determinant to the disease exists and that Asians are not genetically protected. It also implies that the apparent reduction in Paget's disease prevalence in western cities is unlikely to be explicable by the rising Asian population of these cities.

Paget's disease of bone: an update

PURPOSE OF REVIEW

The review summarizes the recent findings relevant to the clinical management, genetic predisposition, and molecular mechanisms implicated in Paget's disease of bone (PDB).

RECENT FINDINGS

PDB is characterized by focal regions of increased bone remodeling and abnormal bone architecture. PDB is treated effectively with amino-bisphosphonates, which can produce very prolonged disease remission. The disease has a strong genetic component and a large number of studies focus on the cellular mechanisms affected by mutations in the SQSTM1 (sequestosome 1) gene which are associated with PDB. Identifying other genes associated with PDB is an additional active research focus.

SUMMARY

In recent years, there has been a great progress in the understanding of the epidemiology, genetics and molecular biology of PDB. However, an integrative view of the disease cause is still missing and is likely to be attained only with further discoveries of genetic factors, environmental factors, and the interactions between them. Investigations of the cellular mechanisms that are disrupted in PDB contribute greatly to the understanding of normal bone remodeling.

Familial Paget disease and SQSTM1 mutations in New Zealand

Genetic factors play an important role in the pathogenesis of Paget disease of bone (PDB). SQSTM1 is the most important disease-associated gene identified to date. We investigated the relationship of family history, phenotype, and SQSTM1 mutation status in New Zealand (a country with a high prevalence of PDB) in patients with a family history and/or a severe phenotype. We studied 61 unrelated subjects with familial PDB. Family history was subclassified into three groups according to the closeness of the relationship. We also studied a fourth group of 19 unrelated patients defined by early onset and/or severe disease but no family history. The PDB phenotype was defined according to age, alkaline phosphatase activity, and disease extent on scintiscan at the time of diagnosis. Mutations in exon 8 of SQSTM1 were detected by screening of genomic DNA. Four different mutations were identified; the ubiquitous P392L mutation and the truncating mutation E396X accounted for 89% of cases. Overall 26% of patients with familial PBD in New Zealand had disease-associated mutations in the SQSTM1 gene. Mutations were most prevalent (60%) in those with a parent or sibling and at least one other relative affected (P < 0.002). The severity of the phenotype was significantly related to SQSTM1 mutation status but not the strength of the family history (P < 0.005). SQSTM1 mutations were found in 10.5% of patients with early onset and/or severe disease but no family history.