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.

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.

Evolution of Paget's disease of bone in adults inheriting SQSTM1 mutations

CONTEXT

The cause of Paget's disease of bone (PDB) is unknown, but genetic factors, particularly SQSTM1 mutations, and environmental factors are important.

OBJECTIVE

To investigate the development of PDB in asymptomatic relatives carrying SQSTM1 mutations to determine whether a secular trend towards a less severe phenotype is evident, and to estimate prospectively the rate at which PDB emerged in this genetically susceptible population.

DESIGN

We recruited first-degree relatives of patients with PDB [33 adult offspring (mean age 45) and 1 sibling] with a familial SQSTM1 mutation. We determined the presence of PDB with skeletal scintiscans and confirmatory radiographs. Those negative for PDB on the initial scan were investigated again a mean 5·1 years later.

RESULTS

The initial skeletal scintiscan demonstrated PDB in six subjects; 26 of the remaining 28 unaffected subjects had a second scintiscan, with two new cases of monostotic PDB diagnosed in 134 patient-years of follow-up. In the total eight adult offspring diagnosed with PDB, the age of diagnosis was greater, by at least 10 years, than that in the 21 probands with clinically identified PDB (P = 0·005). In adult offspring who were older at the time of skeletal scintigraphy than their affected parents were at the time of clinical diagnosis, the difference was even more marked (P < 0·001). In adult offspring with PDB, the disease was significantly less extensive than in their affected parent, as judged by alkaline phosphatase and disease extent (P < 0·003).

CONCLUSION

These findings suggest a substantial gene-environment interaction: the emergence of PDB in offspring inheriting SQSTM1 mutations is delayed by at least a decade, has a substantially attenuated phenotype and occurs at a low rate between the (mean) ages of 45 and 50 years. The nature of the environmental factor is unknown.

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.