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Paget's disease of bone (PDB) is, after osteoporosis, the second most common metabolic bone disorder in the elderly Caucasian population. Mutations in the sequestosome 1 gene (SQSTM1) are responsible for the etiology of PDB in a subset of patients, but the disease pathogenesis in the remaining PDB patients is still unknown. Therefore association studies investigating the relationship between genetic polymorphisms and sporadic PDB have been performed in order to find the susceptibility polymorphisms. In this paper, we sought to determine whether polymorphisms in 3 functional candidate genes play a role in the development of sporadic PDB: TNFSF11 (receptor activator of nuclear factor κB ligand, RANKL), VCP (valosin-containing protein) and IL-6 (interleukin 6). Analyzing 9 tag SNPs and 2 multi-marker tests (MMTs) in TNFSF11, 3 tag SNPs and 1 MMT in VCP and 8 tag SNPs in IL-6 in a population of 196 Belgian patients with sporadic PDB and 212 Belgian control individuals revealed that one VCP SNP (rs565070) turned out to be associated with PDB in this Belgian study population (p=5.5×10(-3)). None of the tag SNPs or MMTs selected for TNFSF11 or IL-6 was associated with PDB. Still, replication of our findings in the VCP gene in other populations is important to confirm our results. However, when combining data of VCP with those from other susceptible gene regions from previous association studies (i.e. TNFRSF11A, CSF1, OPTN and TM7SF4), independent effect of each gene region was found and the cumulative population attributable risk is 72.7%., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Recently, genome-wide association studies have discovered several single nucleotide polymorphisms (SNPs) involved in the etiology of complex obesity. A variant downstream from the melanocortin-4 receptor gene (MC4R), a gene known to be involved in monogenic obesity, was reported to be highly associated with BMI. In the present study, we performed a replication study with the previously reported SNP rs17782313. We also included 3 tagSNPs (rs8087522, rs11872992, and rs1943226) for the MC4R gene region in our study to understand the role of this gene in complex obesity. We genotyped all 4 SNPs in a population of 1049 obese cases (mean BMI=38.2±6.2) and 312 healthy lean individuals (mean BMI 22.0±1.7). We could confirm that rs17782313 is highly associated with complex obesity in our population (odds ratio=1.42, 95% CI 1.14-1.77, P=0.002). Furthermore, we found this SNP to be associated with BMI (B=0.92, 95% CI 0.19-1.65, P=0.01) and body weight (B=2.44, 95% CI 0.28-4.60, P=0.03). In addition, we could also detect an association between rs11872992 and complex obesity (odds ratio=0.74, 95% CI 0.57-0.98, P=0.03). Through conditional analysis, we demonstrate that this effect is independent from the rs17782313 association signal. No associations with obesity could be found for rs8087522 and rs1943226. In conclusion, we could replicate the previously reported association between rs17782313 and complex obesity. Furthermore, our data do not support the hypothesis that a SNP in MC4R causes the rs17782313 association signal., (Copyright © 2011 Elsevier Inc. All rights reserved.)

RANK (receptor activator of nuclear factor-κB), encoded by TNFRSF11A, is a key protein in osteoclastogenesis. TNFRSF11A mutations cause Paget's disease of bone (PDB)-like diseases (ie, familial expansile osteolysis, expansile skeletal hyperphosphatasia, and early-onset PDB) and an osteoclast-poor form of osteopetrosis. However, no TNFRSF11A mutations have been found in classic PDB, neither in familial nor in isolated cases. To investigate the possible relationship between TNFRSF11A polymorphisms and sporadic PDB, we conducted an association study including 32 single-nucleotide polymorphisms (SNPs) in 196 Belgian sporadic PDB patients and 212 control individuals. Thirteen SNPs and 3 multimarker tests (MMTs) turned out to have a p value of between .036 and 3.17 × 10(-4) , with the major effect coming from females. Moreover, 6 SNPs and 1 MMT withstood the Bonferroni correction (p < .002). Replication studies were performed for 2 nonsynonymous SNPs (rs35211496 and rs1805034) in a Dutch and a British cohort. Interestingly, both SNPs resulted in p values ranging from .013 to 8.38 × 10(-5) in both populations. Meta-analysis over three populations resulted in p = .002 for rs35211496 and p = 1.27 × 10(-8) for rs1805034, again mainly coming from the female subgroups. In an attempt to identify the underlying causative SNP, we performed functional studies for the coding SNPs as well as resequencing efforts of a 31-kb region harboring a risk haplotype within the Belgian females. However, neither approach resulted in significant evidence for the causality of any of the tested genetic variants. Therefore, further studies are needed to identify the real cause of the increased risk to develop PDB shown to be present within TNFRSF11A., (Copyright © 2010 American Society for Bone and Mineral Research.)

Sclerosteosis is a rare bone dysplasia characterized by greatly increased bone mass, especially of the long bones and the skull. Patients are tall, show facial asymmetry and often have syndactyly. Clinical complications are due to entrapment of cranial nerves. The disease is thought to be due to loss-of-function mutations in the SOST gene. The SOST gene product, sclerostin, is secreted by osteocytes and transported to the bone surface where it inhibits osteoblastic bone formation by antagonizing Wnt signaling. In a small Turkish family with sclerosteosis, we identified a missense mutation (c.499T>C; p.Cys167Arg) in exon 2 of the SOST gene. This type of mutation has not been previously reported and using different functional approaches, we show that it has a devastating effect on the biological function of sclerostin. The affected cysteine is the last cysteine residue of the cystine-knot motif and loss of this residue leads to retention of the mutant protein in the ER, possibly as a consequence of impaired folding. Together with a significant reduced ability to bind to LRP5 and inhibit Wnt signaling, the p.Cys167Arg mutation leads to a complete loss of function of sclerostin and thus to the characteristic sclerosteosis phenotype., ((c) 2010 Wiley-Liss, Inc.)

Unlabelled: We studied the role of TNFRSF11B polymorphisms on the risk to develop Paget's disease of bone in a Belgian study population. We observed no association in men, but a highly significant association was found in women, and this was confirmed in a population from the United Kingdom., Introduction: Juvenile Paget's disease has been shown to be caused by mutations in TNFRSF11B encoding osteoprotegerin. Although mutations in this gene have never been found in patients with typical Paget's disease of bone (PDB), there are indications that polymorphisms in TNFRSF11B might contribute to the risk of developing PDB., Materials and Methods: We recruited a population of 131 Belgian patients with sporadic PDB and 171 Belgian controls. By means of the HapMap, we selected 17 SNPs that, in combination with four multimarker tests, contain most information on common genetic variation in TNFRSF11B. To replicate the findings observed in the Belgian study population, genotyping data of SNPs generated in a UK population were reanalyzed., Results: In our Belgian study population, associations were found for two SNPs (rs11573871, rs1485286) and for one multimarker test involving rs1032129. When subsequently analyzing men and women separately, these associations turned out to be driven by women (56 cases, 78 controls). In addition, three other tagSNPs turned out to be associated in women only. These were rs2073617 (C950T), rs6415470, and rs11573869. Reanalysis of genotyping data from a UK study population indicated that the associations found for C950T and C1181G were also exclusively driven by women (146 cases, 216 controls). Meta-analysis provided evidence for risk increasing effects of the T allele of C950T and the G allele of C1181G in the female population (p = 0.002 and 0.003, respectively). The haplotypes formed by the SNPs associated in the Belgian population were also distributed differentially between female cases and controls., Conclusions: We showed for the first time that SNPs influencing the risk to develop PDB could be sex-specific. Further research is necessary to identify the causative variants in TNFRSF11B and to elucidate the molecular pathogenic mechanism.