Association tests of interleukin-6 (IL-6) and type II tumor necrosis factor receptor (TNFR2) genes with bone mineral density in Caucasians using a re-sampling approach

Genetic variation and bone mineral density in long-term adult survivors of childhood cancer

PURPOSE

Despite similarities in upfront treatment of childhood cancer, not every adult survivor of childhood cancer (CCS) has an impaired bone mineral density (BMD). No data are available on the role of genetic variation on impairment of BMD in CCS.

METHODS

This cross-sectional single-center cohort study included 334 adult CCSs (median follow-up time after cessation of treatment: 15 years; median age at follow-up: 26 years). Total body BMD (BMD_TB ) and lumbar spine BMD (BMD_LS ) were measured by dual x-ray absorptiometry. We selected 12 candidate single-nucleotide polymorphisms (SNPs) in 11 genes (COL1A1, TNFSF11, TNFRSF11, TNRFSA11B, VDR, ESR1, WLS, LRP5, MTHFR, MTRR, IL-6).

RESULTS

Multivariate analyses revealed that lower BMD was associated with lower weight and height at follow-up, male sex, and previously administered radiotherapy. Survivors with the homozygous minor allele (GG) genotype of rs2504063 (ESR1: estrogen receptor type 1) had a lower BMD_TB values (-1.16 vs. -0.82; P = 0.01) than those with the AG/AA genotype; however, BMD_LS was not different. Carriers of two minor alleles (GG) of rs599083 (LRP5: low-density lipoprotein receptor) revealed lower BMD_TB (-1.20 vs. -0.78; P = 0.02) and lower BMD_LS (-0.95 vs. -0.46; P = 0.01) values than those with the TT/TG genotype.

CONCLUSION

CCSs who are carriers of candidate SNPs in the ESR1 or LRP5 genes seem to have an impaired bone mass at an early adult age. Information on genetic variation, in addition to patient- and treatment-related factors, may be helpful in identifying survivors who are at risk for low bone density after childhood cancer treatment.

Interleukin-16 rs11556218 is associated with a risk of osteoporosis in Chinese postmenopausal women

BACKGROUND

Interleukins (ILs), a multifunctional cytokine, play a fundamental role in inflammatory diseases, as well as in the development of osteoporosis. However, there are no data about the role of IL-16 polymorphism in development of osteoporosis.

PATIENTS AND METHODS

In this study, we investigated the association between the IL-16 rs11556218 T/G and rs4072122 C/T polymorphisms respectively, and the risk of osteoporosis among 230 patients with osteoporosis and 230 healthy controls. Serum IL-16 level and its correlation with the IL-16 rs11556218 T/G genotypes were analyzed.

RESULTS

Significant differences of genotype distribution were observed between osteoporosis cases and controls at the IL-16 rs11556218 T/G genotypes. Compared with the IL-16 rs11556218 T/G homozygote TT, the heterozygous TG genotype was associated with significantly increased risk for osteoporosis (OR=2.29, 95% CI=(1.15-3.82), p=0.026); the GG genotype was associated with increased risk for osteoporosis (OR=1.84, 95% CI=1.48-3.97, p=0.015). TG and GG combined variants that were associated with increased risk for osteoporosis compared with the TT genotype (OR=1.92, 95% CI=1.43-4.86, p=0.023). Moreover, in patients with osteoporosis, there was a correlation between the serum IL-16 and rs11556218 T/G genotype. However, the genotype and allele frequencies of IL-16 rs4072122 C/T polymorphisms in osteoporosis patients were not significantly different from controls.

CONCLUSION

IL-16 rs11556218 T/G genotype was associated with increased risk for development of osteoporosis in Chinese postmenopausal women.

Association of IL-6 G-174C polymorphism with bone mineral density

Functional polymorphisms in the promoter region of interleukin-6 (IL-6) are known to be involved in bone mineral density (BMD) and the development of osteoporosis, but the reported results have been inconsistent. Using the meta-analysis approach, the present study is designed to provide a relatively comprehensive picture of the relationship between bone mineral density (BMD) or osteoporosis and polymorphisms in the promoter region of IL-6 (rs1800795 and rs1800796). The difference of bone mineral density (BMD) values between genotypes was examined by mean difference and 95 % confidence intervals (CIs). Association between IL-6 polymorphism and clinical osteoporosis was evaluated by pooled odds ratios (ORs) and 95 % CIs. A total of 13 articles with 11,499 subjects were included in the present study. For -174 (rs1800795), we found that individuals with the G/G genotype had a significantly lower BMD value than those with C/C genotype at femoral neck (0.02 g/cm(2), 95 % CI 0.00-0.03) (p = 0.04) and distal radius (0.01 g/cm(2), 95 %CI 0.01-0.01) (p < 0.0001). However, we did not find a statistically significant difference of BMD at the spine. When analysis was limited to postmenopausal women, similar results were obtained. We further found that the C/C genotype was associated with a reduced risk of osteoporosis compared to G/G genotype, and the pooled OR was 0.72 (95 % CI 0.54-0.95, p = 0.02). In addition, a significant relationship was found between G-634C (rs1800796) polymorphism and distal radius BMD (CC vs. GG: 0.02 g/cm(2), 95 % CI 0.01-0.03; GC vs. GG: 0.02 g/cm(2), 95 % CI 0.00-0.03) in the Asian population. These findings suggest that the CC genotype of IL-6 G-174C polymorphism may be associated with high BMD at femoral neck and distal radius and decreased risk of osteoporosis in the Caucasian population whereas G-634C polymorphism was associated with distal radius BMD in Asians.

Linkage mapping of principal components for femoral biomechanical performance in a reciprocal HCB-8 × HCB-23 intercross

Studies of bone genetics have addressed an array of related phenotypes, including various measures of biomechanical performance, bone size, bone, shape, and bone mineral density. These phenotypes are not independent, resulting in redundancy of the information they provide. Principal component (PC) analysis transforms multiple phenotype data to a new set of orthogonal "synthetic" phenotypes. We performed PC analysis on 17 femoral biomechanical, anatomic, and body size phenotypes in a reciprocal intercross of HcB-8 and HcB-23, accounting for 80% of the variance in 4 PCs. Three of the 4 PCs were mapped in the cross. The linkage analysis revealed a quantitative trait locus (QTL) with LOD = 4.7 for PC2 at 16 cM on chromosome 19 that was not detected using the directly measured phenotypes. The chromosome 19 QTL falls within a ~10 megabase interval, with Osf1 as a positional candidate gene. PC QTLs were also found on chromosomes 1, 2, 4, 6, and 10 that coincided with those identified for directly measured or calculated material property phenotypes. The novel chromosome 19 QTL illustrates the power advantage that attends use of PC phenotypes for linkage mapping. Constraint of the chromosome 19 candidate interval illustrates an important advantage of experimental crosses between recombinant congenic mouse strains.

Association analyses of RANKL/RANK/OPG gene polymorphisms with femoral neck compression strength index variation in Caucasians

Femoral neck compression strength index (fCSI), a novel phenotypic parameter that integrates bone density, bone size, and body size, has significant potential to improve hip fracture risk assessment. The genetic factors underlying variations in fCSI, however, remain largely unknown. Given the important roles of the receptor activator of the nuclear factor-kappaB ligand/receptor activator of the nuclear factor-kappaB/osteoprotegerin (RANKL/RANK/OPG) pathway in the regulation of bone remodeling, we tested the associations between RANKL/RANK/OPG polymorphisms and variations in fCSI as well as its components (femoral neck bone mineral density [fBMD], femoral neck width [FNW], and weight). This was accomplished with a sample comprising 1873 subjects from 405 Caucasian nuclear families. Of the 37 total SNPs studied in these three genes, 3 SNPs, namely, rs12585014, rs7988338, and rs2148073, of RANKL were significantly associated with fCSI (P = 0.0007, 0.0007, and 0.0005, respectively) after conservative Bonferroni correction. Moreover, the three SNPs were approximately in complete linkage disequilibrium. Haplotype-based association tests corroborated the single-SNP results since haplotype 1 of block 1 of the RANKL gene achieved an even more significant association with fCSI (P = 0.0003) than any of the individual SNPs. However, we did not detect any significant associations of these genes with fBMD, FNW, or weight. In summary, our findings suggest that the RANKL gene may play an important role in variation in fCSI, independent of fBMD and non-fBMD components.

Genetics of bone loss in rheumatoid arthritis--role of vitamin D receptor polymorphisms

RA is a systemic inflammatory arthritis that leads to local and systemic bone loss. Osteoporosis or the systemic bone loss associated with RA increases the risk for fragility fractures, which can affect quality of life dramatically in RA patients. Although traditional and RA-related risk factors have been defined and studied for osteoporosis associated with RA, genetic factors such as polymorphic variants in the traditional candidate genes for osteoporosis, such as the vitamin D receptor (VDR), type 1 collagen A1 (COLIA1) and oestrogen receptor-alpha (ESR1), have not been well elucidated in RA patients. This review summarizes the currently available literature on the association of VDR polymorphisms with local and systemic bone loss in RA. It also discusses potential targets for genetic research in this area, such as polymorphisms in genes, such as IL-6 (IL6) and TNF receptor type 2 (TNFRSF1B), which control the inflammatory response in RA and may influence bone loss in RA. Defining such genetic factors, in addition to traditional and RA-related risk factors for osteoporosis in RA, may facilitate early identification of patients at high risk for fractures who can then be targeted for treatment.

Bone structural effects of variation in the TNFRSF1B gene encoding the tumor necrosis factor receptor 2

The 1p36 region of the human genome has been identified as containing a QTL for BMD in multiple studies. We analysed the TNFRSF1B gene from this region, which encodes the TNF receptor 2, in two large population-based cohorts. Our results suggest that variation in TNFRSF1B is associated with BMD.

INTRODUCTION

The TNFRSF1B gene, encoding the TNF receptor 2, is a strong positional and functional candidate gene for impaired bone structure through the role that TNF has in bone cells. The aims of this study were to evaluate the role of variations in the TNFRSF1B gene on bone structure and osteoporotic fracture risk in postmenopausal women.

METHODS

Six SNPs in TNFRSF1B were analysed in a cohort of 1,190 postmenopausal Australian women, three of which were also genotyped in an independent cohort of 811 UK postmenopausal women. Differences in phenotypic means for genotype groups were examined using one-way ANOVA and ANCOVA.

RESULTS

Significant associations were seen for IVS1+5580A>G with BMD and QUS parameters in the Australian population (P = 0.008 - 0.034) and with hip BMD parameters in the UK population (P = 0.005 - 0.029). Significant associations were also observed between IVS1+6528G>A and hip BMD parameters in the UK cohort (P = 0.0002 - 0.003). We then combined the data from the two cohorts and observed significant associations between both IVS1+5580A>G and IVS1+6528G>A and hip BMD parameters (P = 0.002 - 0.033).

CONCLUSIONS

Genetic variation in TNFRSF1B plays a role in the determination of bone structure in Caucasian postmenopausal women, possibly through effects on osteoblast and osteoclast differentiation.

Molecular genetic studies of gene identification for osteoporosis

This review comprehensively summarizes the most important and representative molecular genetics studies of gene identification for osteoporosis published up to the end of September 2007. It is intended to constitute a sequential update of our previously published reviews covering the available data up to the end of 2004. Evidence from candidate gene-association studies, genome-wide linkage and association studies, as well as functional genomic studies (including gene-expression microarray and proteomics) on osteogenesis and osteoporosis, are reviewed separately. Studies of transgenic and knockout mice models relevant to osteoporosis are summarized. The major results of all studies are tabulated for comparison and ease of reference. Comments are made on the most notable findings and representative studies for their potential influence and implications on our present understanding of genetics of osteoporosis. The format adopted by this review should be ideal for accommodating future new advances and studies.