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Sökning: WFRF:(Albagha Omar)

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  • Albagha, Omar M E, et al. (författare)
  • Linkage disequilibrium between polymorphisms in the human TNFRSF1B gene and their association with bone mass in perimenopausal women
  • 2002
  • Ingår i: Human Molecular Genetics. - Oxford University Press. - 0964-6906. ; 11:19, s. 95-2289
  • Tidskriftsartikel (refereegranskat)abstract
    • Osteoporosis is a multifactorial disease with a strong genetic component characterized by reduced bone density and increased fracture risk. A candidate locus for regulation of hip bone mineral density (BMD) has been identified on chromosome 1p36 by linkage analysis. One of the positional and functional candidate genes located within this region is the tumour necrosis factor receptor superfamily member 1B (TNFRSF1B). In order to investigate whether allelic variation in TNFRSF1B contributes to regulation of bone mass, we studied several polymorphisms of this gene in a population based cohort study of 1240 perimenopausal women from the UK. We studied a T676G change in exon 6 (196: Met-Arg) and three SNPs (G593A, T598G, and T620C) in the 3'UTR of the gene. The 3'UTR SNPs were in strong linkage disequilibrium (LD) with each other (P<0.00001), and the exon 6 SNP was in LD with G593A and T598G (P<0.00001). We found no association between T676G alleles and BMD at the spine or hip. However, haplotype analysis showed that subjects homozygous for the A593-T598-C620 haplotype (n=85) had femoral neck BMD values 5.7% lower than those who did not carry the haplotype (n=1155; P<0.00008) and this remained significant after correcting for confounding factors and multiple testing (P<0.0009). Regression analysis showed that the ATC haplotype accounted for 1.2% of the population variance in hip BMD and was the second strongest predictor after body weight. In summary, our work supports the view that allelic variation in the 3'UTR of TNFRSF1B gene contributes to the genetic regulation of bone mass, with effects that are specific for femoral neck BMD.
  • Estrada, Karol, et al. (författare)
  • Genome-wide meta-analysis identifies 56 bone mineral density loci and reveals 14 loci associated with risk of fracture.
  • 2012
  • Ingår i: Nature genetics. - 1546-1718. ; 44:5, s. 491-501
  • Tidskriftsartikel (refereegranskat)abstract
    • Bone mineral density (BMD) is the most widely used predictor of fracture risk. We performed the largest meta-analysis to date on lumbar spine and femoral neck BMD, including 17 genome-wide association studies and 32,961 individuals of European and east Asian ancestry. We tested the top BMD-associated markers for replication in 50,933 independent subjects and for association with risk of low-trauma fracture in 31,016 individuals with a history of fracture (cases) and 102,444 controls. We identified 56 loci (32 new) associated with BMD at genome-wide significance (P &lt; 5 x 10(-8)). Several of these factors cluster within the RANK-RANKL-OPG, mesenchymal stem cell differentiation, endochondral ossification and Wnt signaling pathways. However, we also discovered loci that were localized to genes not known to have a role in bone biology. Fourteen BMD-associated loci were also associated with fracture risk (P &lt; 5 x 10(-4), Bonferroni corrected), of which six reached P &lt; 5 x 10(-8), including at 18p11.21 (FAM210A), 7q21.3 (SLC25A13), 11q13.2 (LRP5), 4q22.1 (MEPE), 2p16.2 (SPTBN1) and 10q21.1 (DKK1). These findings shed light on the genetic architecture and pathophysiological mechanisms underlying BMD variation and fracture susceptibility.
  • Haycock, Philip C., et al. (författare)
  • Association Between Telomere Length and Risk of Cancer and Non-Neoplastic Diseases A Mendelian Randomization Study
  • 2017
  • Ingår i: JAMA Oncology. - American Medical Association. - 2374-2437. ; 3:5, s. 636-651
  • Tidskriftsartikel (refereegranskat)abstract
    • IMPORTANCE: The causal direction and magnitude of the association between telomere length and incidence of cancer and non-neoplastic diseases is uncertain owing to the susceptibility of observational studies to confounding and reverse causation. OBJECTIVE: To conduct a Mendelian randomization study, using germline genetic variants as instrumental variables, to appraise the causal relevance of telomere length for risk of cancer and non-neoplastic diseases. DATA SOURCES: Genomewide association studies (GWAS) published up to January 15, 2015. STUDY SELECTION: GWAS of noncommunicable diseases that assayed germline genetic variation and did not select cohort or control participants on the basis of preexisting diseases. Of 163 GWAS of noncommunicable diseases identified, summary data from 103 were available. DATA EXTRACTION AND SYNTHESIS: Summary association statistics for single nucleotide polymorphisms (SNPs) that are strongly associated with telomere length in the general population. MAIN OUTCOMES AND MEASURES: Odds ratios (ORs) and 95% confidence intervals (CIs) for disease per standard deviation (SD) higher telomere length due to germline genetic variation. RESULTS: Summary data were available for 35 cancers and 48 non-neoplastic diseases, corresponding to 420 081 cases (median cases, 2526 per disease) and 1 093 105 controls (median, 6789 per disease). Increased telomere length due to germline genetic variation was generally associated with increased risk for site-specific cancers. The strongest associations (ORs [ 95% CIs] per 1-SD change in genetically increased telomere length) were observed for glioma, 5.27 (3.15-8.81); serous low-malignant-potential ovarian cancer, 4.35 (2.39-7.94); lung adenocarcinoma, 3.19 (2.40-4.22); neuroblastoma, 2.98 (1.92-4.62); bladder cancer, 2.19 (1.32-3.66); melanoma, 1.87 (1.55-2.26); testicular cancer, 1.76 (1.02-3.04); kidney cancer, 1.55 (1.08-2.23); and endometrial cancer, 1.31 (1.07-1.61). Associations were stronger for rarer cancers and at tissue sites with lower rates of stem cell division. There was generally little evidence of association between genetically increased telomere length and risk of psychiatric, autoimmune, inflammatory, diabetic, and other non-neoplastic diseases, except for coronary heart disease (OR, 0.78 [ 95% CI, 0.67-0.90]), abdominal aortic aneurysm (OR, 0.63 [ 95% CI, 0.49-0.81]), celiac disease (OR, 0.42 [ 95% CI, 0.28-0.61]) and interstitial lung disease (OR, 0.09 [ 95% CI, 0.05-0.15]). CONCLUSIONS AND RELEVANCE: It is likely that longer telomeres increase risk for several cancers but reduce risk for some non-neoplastic diseases, including cardiovascular diseases.
  • Ioannidis, John P A, et al. (författare)
  • Differential genetic effects of ESR1 gene polymorphisms on osteoporosis outcomes
  • 2004
  • Ingår i: JAMA - Journal of the American Medical Association. - American Medical Association. - 0002-9955. ; 292:17, s. 14-2105
  • Tidskriftsartikel (refereegranskat)abstract
    • CONTEXT: Both bone mineral density (BMD) and fracture risk have a strong genetic component. Estrogen receptor alpha (ESR1) is a candidate gene for osteoporosis, but previous studies of ESR1 polymorphisms in this field were hampered by small sample size, lack of standardization, and inconclusive results.OBJECTIVE: To generate large-scale evidence on whether 3 common ESR1 polymorphisms (intron 1 polymorphisms XbaI [dbSNP: rs9340799] and PvuII [dbSNP: rs2234693] and promoter TA repeats microsatellite) and haplotypes thereof are associated with BMD and fractures.DESIGN AND SETTING: Meta-analysis of individual-level data involving standardized genotyping of 18 917 individuals in 8 European centers.MAIN OUTCOME MEASURES: BMD of femoral neck and lumbar spine; all fractures and vertebral fractures by genotype.RESULTS: No between-center heterogeneity was observed for any outcome in any genetic contrast. None of the 3 polymorphisms or haplotypes had any statistically significant effect on BMD in adjusted or unadjusted analyses, and estimated differences between genetic contrasts were 0.01 g/cm2 or less. Conversely, we found significant reductions in fracture risk. In women homozygous for the absence of an XbaI recognition site, the adjusted odds of all fractures were reduced by 19% (odds ratio, 0.81 [95% CI, 0.71-0.93]; P = .002) and vertebral fractures by 35% (odds ratio, 0.65 [95% CI, 0.49-0.87]; P = .003). Effects on fractures were independent of BMD and unaltered in adjusted analyses. No significant effects on fracture risk were seen for PvuII and TA repeats.CONCLUSIONS: ESR1 is a susceptibility gene for fractures, and XbaI determines fracture risk by mechanisms independent of BMD. Our study demonstrates the value of adequately powered studies with standardized genotyping and clinical outcomes in defining effects of common genetic variants on complex diseases.
  • Parsons, Claire A, et al. (författare)
  • Interspecies synteny mapping identifies a quantitative trait locus for bone mineral density on human chromosome Xp22
  • 2005
  • Ingår i: Human Molecular Genetics. - Oxford University Press. - 0964-6906. ; 14:21, s. 8-3141
  • Tidskriftsartikel (refereegranskat)abstract
    • Bone mineral density (BMD) is a complex trait with a strong genetic component and an important predictor of osteoporotic fracture risk. Here we report the use of a cross-species strategy to identify genes that regulate BMD, proceeding from quantitative trait mapping in mice to association mapping of the syntenic region in the human genome. We identified a quantitative trait locus (QTL) on the mouse X-chromosome for post-maturity change in spine BMD in a cross of SAMP6 and AKR/J mice and conducted association mapping of the syntenic region on human chromosome Xp22. We studied 76 single nucleotide polymorphisms (SNP) from the human region in two sets of DNA pools prepared from individuals with lumbar spine-BMD (LS-BMD) values falling into the top and bottom 13th percentiles of a population-based study of 3100 post-menopausal women. This procedure identified a region of significant association for two adjacent SNP (rs234494 and rs234495) within the Xp22 locus (P<0.001). Individual genotyping for rs234494 in the BMD pools confirmed the presence of an association for alleles (P=0.018) and genotypes (P=0.008). Analysis of rs234494 and rs234495 in 1053 women derived from the same population who were not selected for BMD values showed an association with LS-BMD for rs234495 (P=0.01) and for haplotypes defined by both SNP (P=0.002). Our study illustrates that interspecies synteny can be used to identify and refine QTL for complex traits and represents the first example where a human QTL for BMD regulation has been mapped using this approach.
  • Pettersson, Ulrika, et al. (författare)
  • Polymorphisms of the CLCN7 gene are associated with BMD in women
  • 2005
  • Ingår i: Journal of Bone and Mineral Research. - AMBMR. - 0884-0431. ; 20:11, s. 7-1960
  • Tidskriftsartikel (refereegranskat)abstract
    • UNLABELLED: Here we show that a common polymorphism causing a valine to methionine amino acid substitution at codon 418 (V418M) in the CLCN7 gene is associated with femoral neck BMD in women. Our study adds to accumulating evidence that shows that common allelic variants in monogenic bone disease genes often contribute to BMD regulation in normal subjects.INTRODUCTION: The CLCN7 gene is a strong candidate for regulation of BMD, because mutations in CLCN7 cause some forms of osteopetrosis, a disease characterized by impaired osteoclast function and increased BMD. In this study, we sought to determine whether common allelic variation within CLCN7 was associated with BMD in the normal population.MATERIALS AND METHODS: We conducted mutation screening of the exons and intron-exon boundaries in CLCN7 by DNA sequencing in 50 normal subjects. We conducted an association study between common polymorphisms in CLCN7 and haplotypes defined by these polymorphisms and BMD values at the lumbar spine and femoral neck in a population-based cohort study of 1077 Scottish women 45-55 years of age.RESULTS: We identified 24 polymorphisms, but most were rare and only 4 had allele frequencies of >5%. These were a conservative single nucleotide polymorphism (SNP) in exon 1 (rs3751884), a 50-bp tandem repeat polymorphism within intron 8, and two SNPs within exon 15 (rs12926089 and rs12926669), of which one (rs12926669) predicts an amino acid change from valine to methionine at codon 418 (V418M). The exon 15 SNPs were in strong linkage disequilibrium and were both associated with femoral neck BMD (p = 0.001-0.003). None of the other polymorphisms were associated with BMD, and long-range haplotypes showed a much weaker association with BMD than the exon 15 SNPs. The V418M polymorphism was an independent predictor of femoral neck BMD on multiple regression analysis accounting for 1% of the variance in BMD at this site.CONCLUSIONS: Our study indicates that the V418M polymorphism of CLCN7 contributes to the genetic regulation of femoral neck BMD in women and adds to accumulating evidence that indicates that subtle polymorphic variation in genes that cause monogenic bone diseases also contribute to regulation of BMD in normal subjects.
  • Stewart, Tracy L, et al. (författare)
  • Haplotypes defined by promoter and intron 1 polymorphisms of the COLIA1 gene regulate bone mineral density in women
  • 2006
  • Ingår i: Journal of Clinical Endocrinology and Metabolism. - The Endocrine Society. - 1945-7197. ; 91:9, s. 3575-3583
  • Tidskriftsartikel (refereegranskat)abstract
    • CONTEXT: The COLIA1 gene is a strong candidate for susceptibility to osteoporosis. The causal genetic variants are currently unclear, but the most likely are functional polymorphisms in the promoter and intron 1 of COLIA1. OBJECTIVE: The objective of the study was to determine whether promoter and intron 1 polymorphisms of COLIA1 or haplotypes defined by these polymorphisms regulate bone mineral density (BMD) in women. DESIGN: This was a population-based association study involving 3270 women from the United Kingdom who took part in a regional osteoporosis screening program. MAIN OUTCOME MEASURES: BMD at the lumbar spine (LS-BMD) and femoral neck (FN-BMD) was measured on two occasions approximately 6 yr apart, in relation to polymorphisms and haplotypes defined by polymorphisms within the COLIA1 intron 1 (+1245G/T; rs1800012) and promoter (-1997G/T; rs1107946; -1663IndelT; rs2412298). RESULTS: The polymorphisms were in strong linkage disequilibrium, and three haplotypes accounted for more than 95% of alleles at the COLIA1 locus. The individual polymorphisms were associated with BMD, but the most consistent associations were with haplotypes defined by all three polymorphisms. Homozygote carriers of haplotype 2 (-1997G/-1663delT/+1245T) had reduced BMD at baseline (P = 0.007 for LS-BMD; P = 0.008 for FN-BMD), whereas homozygotes for haplotype 3 (-1997T/-1663insT/+1245G) had increased BMD (P = 0.007 for LS-BMD). Similar associations were observed at follow-up for haplotype 3, but the association with haplotype 2 was weaker due to increased uptake of hormone replacement therapy in homozygotes for this haplotype. CONCLUSIONS: Two haplotypes defined by polymorphisms in the 5' flank of the COLIA1 regulate BMD in a bidirectional manner in women.
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