1. |
- Locke, Adam E, et al.
(author)
-
Genetic studies of body mass index yield new insights for obesity biology.
- 2015
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 518:7538, s. 197-401
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Journal article (peer-reviewed)abstract
- Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10(-8)), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ∼2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.
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2. |
- Turcot, Valerie, et al.
(author)
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Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity
- 2018
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In: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 50:1, s. 26-41
-
Journal article (peer-reviewed)abstract
- Genome-wide association studies (GWAS) have identified >250 loci for body mass index (BMI), implicating pathways related to neuronal biology. Most GWAS loci represent clusters of common, noncoding variants from which pinpointing causal genes remains challenging. Here we combined data from 718,734 individuals to discover rare and low-frequency (minor allele frequency (MAF) < 5%) coding variants associated with BMI. We identified 14 coding variants in 13 genes, of which 8 variants were in genes (ZBTB7B, ACHE, RAPGEF3, RAB21, ZFHX3, ENTPD6, ZFR2 and ZNF169) newly implicated in human obesity, 2 variants were in genes (MC4R and KSR2) previously observed to be mutated in extreme obesity and 2 variants were in GIPR. The effect sizes of rare variants are similar to 10 times larger than those of common variants, with the largest effect observed in carriers of an MC4R mutation introducing a stop codon (p.Tyr35Ter, MAF = 0.01%), who weighed similar to 7 kg more than non-carriers. Pathway analyses based on the variants associated with BMI confirm enrichment of neuronal genes and provide new evidence for adipocyte and energy expenditure biology, widening the potential of genetically supported therapeutic targets in obesity.
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3. |
- Marouli, Eirini, et al.
(author)
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Rare and low-frequency coding variants alter human adult height
- 2017
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 542:7640, s. 186-190
-
Journal article (peer-reviewed)abstract
- Height is a highly heritable, classic polygenic trait with approximately 700 common associated variants identified through genome-wide association studies so far. Here, we report 83 height-associated coding variants with lower minor-allele frequencies (in the range of 0.1-4.8%) and effects of up to 2 centimetres per allele (such as those in IHH, STC2, AR and CRISPLD2), greater than ten times the average effect of common variants. In functional follow-up studies, rare height increasing alleles of STC2 (giving an increase of 1-2 centimetres per allele) compromised proteolytic inhibition of PAPP-A and increased cleavage of IGFBP-4 in vitro, resulting in higher bioavailability of insulin-like growth factors. These 83 height-associated variants overlap genes that are mutated in monogenic growth disorders and highlight new biological candidates (such as ADAMTS3, IL11RA and NOX4) and pathways (such as proteoglycan and glycosaminoglycan synthesis) involved in growth. Our results demonstrate that sufficiently large sample sizes can uncover rare and low-frequency variants of moderate-to-large effect associated with polygenic human phenotypes, and that these variants implicate relevant genes and pathways.
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4. |
- Shungin, Dmitry, et al.
(author)
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New genetic loci link adipose and insulin biology to body fat distribution.
- 2015
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 518:7538, s. 187-378
-
Journal article (peer-reviewed)abstract
- Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms.
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5. |
- Kattge, Jens, et al.
(author)
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TRY plant trait database - enhanced coverage and open access
- 2020
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In: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
-
Journal article (peer-reviewed)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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6. |
- van Rheenen, Wouter, et al.
(author)
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Genome-wide association analyses identify new risk variants and the genetic architecture of amyotrophic lateral sclerosis
- 2016
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 48:9, s. 1043-1048
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Journal article (peer-reviewed)abstract
- To elucidate the genetic architecture of amyotrophic lateral sclerosis (ALS) and find associated loci, we assembled a custom imputation reference panel from whole-genome-sequenced patients with ALS and matched controls (n = 1,861). Through imputation and mixed-model association analysis in 12,577 cases and 23,475 controls, combined with 2,579 cases and 2,767 controls in an independent replication cohort, we fine-mapped a new risk locus on chromosome 21 and identified C21orf2 as a gene associated with ALS risk. In addition, we identified MOBP and SCFD1 as new associated risk loci. We established evidence of ALS being a complex genetic trait with a polygenic architecture. Furthermore, we estimated the SNP-based heritability at 8.5%, with a distinct and important role for low-frequency variants (frequency 1-10%). This study motivates the interrogation of larger samples with full genome coverage to identify rare causal variants that underpin ALS risk.
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7. |
- Ried, Janina S., et al.
(author)
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A principal component meta-analysis on multiple anthropometric traits identifies novel loci for body shape
- 2016
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
-
Journal article (peer-reviewed)abstract
- Large consortia have revealed hundreds of genetic loci associated with anthropometric traits, one trait at a time. We examined whether genetic variants affect body shape as a composite phenotype that is represented by a combination of anthropometric traits. We developed an approach that calculates averaged PCs (AvPCs) representing body shape derived from six anthropometric traits (body mass index, height, weight, waist and hip circumference, waist-to-hip ratio). The first four AvPCs explain >99% of the variability, are heritable, and associate with cardiometabolic outcomes. We performed genome-wide association analyses for each body shape composite phenotype across 65 studies and meta-analysed summary statistics. We identify six novel loci: LEMD2 and CD47 for AvPC1, RPS6KA5/C14orf159 and GANAB for AvPC3, and ARL15 and ANP32 for AvPC4. Our findings highlight the value of using multiple traits to define complex phenotypes for discovery, which are not captured by single-trait analyses, and may shed light onto new pathways.
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8. |
- Sawcer, Stephen, et al.
(author)
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Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis
- 2011
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 476:7359, s. 214-219
-
Journal article (peer-reviewed)abstract
- Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis.
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9. |
- Birney, Ewan, et al.
(author)
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Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project
- 2007
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 447:7146, s. 799-816
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Journal article (peer-reviewed)abstract
- We report the generation and analysis of functional data from multiple, diverse experiments performed on a targeted 1% of the human genome as part of the pilot phase of the ENCODE Project. These data have been further integrated and augmented by a number of evolutionary and computational analyses. Together, our results advance the collective knowledge about human genome function in several major areas. First, our studies provide convincing evidence that the genome is pervasively transcribed, such that the majority of its bases can be found in primary transcripts, including non-protein-coding transcripts, and those that extensively overlap one another. Second, systematic examination of transcriptional regulation has yielded new understanding about transcription start sites, including their relationship to specific regulatory sequences and features of chromatin accessibility and histone modification. Third, a more sophisticated view of chromatin structure has emerged, including its inter-relationship with DNA replication and transcriptional regulation. Finally, integration of these new sources of information, in particular with respect to mammalian evolution based on inter- and intra-species sequence comparisons, has yielded new mechanistic and evolutionary insights concerning the functional landscape of the human genome. Together, these studies are defining a path for pursuit of a more comprehensive characterization of human genome function.
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10. |
- Jones, Gregory T., et al.
(author)
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Meta-Analysis of Genome-Wide Association Studies for Abdominal Aortic Aneurysm Identifies Four New Disease-Specific Risk Loci
- 2017
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In: Circulation Research. - 0009-7330 .- 1524-4571. ; 120:2, s. 341-
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Journal article (peer-reviewed)abstract
- Rationale: Abdominal aortic aneurysm (AAA) is a complex disease with both genetic and environmental risk factors. Together, 6 previously identified risk loci only explain a small proportion of the heritability of AAA. Objective: To identify additional AAA risk loci using data from all available genome-wide association studies. Methods and Results: Through a meta-analysis of 6 genome-wide association study data sets and a validation study totaling 10 204 cases and 107 766 controls, we identified 4 new AAA risk loci: 1q32.3 (SMYD2), 13q12.11 (LINC00540), 20q13.12 (near PCIF1/MMP9/ZNF335), and 21q22.2 (ERG). In various database searches, we observed no new associations between the lead AAA single nucleotide polymorphisms and coronary artery disease, blood pressure, lipids, or diabetes mellitus. Network analyses identified ERG, IL6R, and LDLR as modifiers of MMP9, with a direct interaction between ERG and MMP9. Conclusions: The 4 new risk loci for AAA seem to be specific for AAA compared with other cardiovascular diseases and related traits suggesting that traditional cardiovascular risk factor management may only have limited value in preventing the progression of aneurysmal disease.
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11. |
- Joshi, Peter K, et al.
(author)
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Directional dominance on stature and cognition in diverse human populations
- 2015
-
In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 523:7561, s. 459-462
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Journal article (peer-reviewed)abstract
- Homozygosity has long been associated with rare, often devastating, Mendelian disorders, and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness. However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power. Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment (P < 1 × 10(-300), 2.1 × 10(-6), 2.5 × 10(-10) and 1.8 × 10(-10), respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months' less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection, this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been.
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12. |
- Koettgen, Anna, et al.
(author)
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Genome-wide association analyses identify 18 new loci associated with serum urate concentrations
- 2013
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 45:2, s. 145-154
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Journal article (peer-reviewed)abstract
- Elevated serum urate concentrations can cause gout, a prevalent and painful inflammatory arthritis. By combining data from >140,000 individuals of European ancestry within the Global Urate Genetics Consortium (GUGC), we identified and replicated 28 genome-wide significant loci in association with serum urate concentrations (18 new regions in or near TRIM46, INHBB, SEMBT1, TMEM171, VEGFA, BAZ1B, PRKAG2, STC1, HNF4G, A1CF, ATXN2, UBE2Q2, IGF1R, NFAT5, MAF, HLF, ACVR1B-ACVRL1 and B3GNT4). Associations for many of the loci were of similar magnitude in individuals of non-European ancestry. We further characterized these loci for associations with gout, transcript expression and the fractional excretion of urate. Network analyses implicate the inhibins-activins signaling pathways and glucose metabolism in systemic urate control. New candidate genes for serum urate concentration highlight the importance of metabolic control of urate production and excretion, which may have implications for the treatment and prevention of gout.
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13. |
- van der Harst, Pim, et al.
(author)
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Seventy-five genetic loci influencing the human red blood cell
- 2012
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 492:7429, s. 369-375
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Journal article (peer-reviewed)abstract
- Anaemia is a chief determinant of global ill health, contributing to cognitive impairment, growth retardation and impaired physical capacity. To understand further the genetic factors influencing red blood cells, we carried out a genome-wide association study of haemoglobin concentration and related parameters in up to 135,367 individuals. Here we identify 75 independent genetic loci associated with one or more red blood cell phenotypes at P < 10(-8), which together explain 4-9% of the phenotypic variance per trait. Using expression quantitative trait loci and bioinformatic strategies, we identify 121 candidate genes enriched in functions relevant to red blood cell biology. The candidate genes are expressed preferentially in red blood cell precursors, and 43 have haematopoietic phenotypes in Mus musculus or Drosophila melanogaster. Through open-chromatin and coding-variant analyses we identify potential causal genetic variants at 41 loci. Our findings provide extensive new insights into genetic mechanisms and biological pathways controlling red blood cell formation and function.
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14. |
- Klimkowska, Agata, et al.
(author)
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Are we restoring functional fens? : The outcomes of restoration projects in fens re-analysed with plant functional traits
- 2019
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In: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 14:4
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Journal article (peer-reviewed)abstract
- In peatland restoration we often lack an information whether re-established ecosystems are functionally similar to non-degraded ones. We re-analysed the long-term outcomes of restoration on vegetation and plant functional traits in 38 European fens restored by rewetting (18 sites) and topsoil removal (20 sites). We used traits related to nutrient acquisition strategies, competitiveness, seed traits, and used single- and multi-trait metrics. A separate set of vegetation records from near-natural fens with diverse plant communities was used to generate reference values to aid the comparisons. We found that both restoration methods enhanced the similarity of species composition to non-degraded systems but trait analysis revealed differences between the two approaches. Traits linked to nutrient acquisition strategies indicated that topsoil removal was more effective than rewetting. After topsoil removal competitive species in plant communities had decreased, while stress-tolerant species had increased. A substantial reduction in nutrient availability ruled out the effect of initial disturbance. An ability to survive and grow in anoxic conditions was enhanced after restoration, but the reference values were not achieved. Rewetting was more effective than topsoil removal in restricting variation in traits values permitted in re-developing vegetation. We found no indication of a shift towards reference in seed traits, which suggested that dispersal constraint and colonization deficit can be a widespread phenomena. Two functional diversity indices: functional richness and functional dispersion showed response to restoration and shifted values towards reference mires and away from the degraded systems. We concluded that targeting only one type of environmental stressor does not lead to a recovery of fens, as it provides insufficient level of stress to restore a functional ecosystem. In general, restoration efforts do not ensure the re-establishment and long-term persistence of fens. Restoration efforts result in recovery of fen ecosystems, confirmed with our functional trait analysis, although more rigid actions are needed for restoring fully functional mires, by achieving high and constant levels of anoxia and nutrient stresses.
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15. |
- Lu, Yingchang, et al.
(author)
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New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk
- 2016
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
-
Journal article (peer-reviewed)abstract
- To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10(-8)), of which eight were previously associated with increased overall adiposity (BMI, BF%) and four (in or near COBLL1/GRB14, IGF2BP1, PLA2G6, CRTC1) were novel associations with BF%. Seven loci showed a larger effect on BF% than on BMI, suggestive of a primary association with adiposity, while five loci showed larger effects on BMI than on BF%, suggesting association with both fat and lean mass. In particular, the loci more strongly associated with BF% showed distinct cross-phenotype association signatures with a range of cardiometabolic traits revealing new insights in the link between adiposity and disease risk.
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16. |
- van Es, Michael A, et al.
(author)
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Angiogenin variants in Parkinson disease and amyotrophic lateral sclerosis
- 2011
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In: Annals of Neurology. - : Wiley-Blackwell. - 0364-5134 .- 1531-8249. ; 70:6, s. 964-973
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Several studies have suggested an increased frequency of variants in the gene encoding angiogenin (ANG) in patients with amyotrophic lateral sclerosis (ALS). Interestingly, a few ALS patients carrying ANG variants also showed signs of Parkinson disease (PD). Furthermore, relatives of ALS patients have an increased risk to develop PD, and the prevalence of concomitant motor neuron disease in PD is higher than expected based on chance occurrence. We therefore investigated whether ANG variants could predispose to both ALS and PD.METHODS: We reviewed all previous studies on ANG in ALS and performed sequence experiments on additional samples, which allowed us to analyze data from 6,471 ALS patients and 7,668 controls from 15 centers (13 from Europe and 2 from the USA). We sequenced DNA samples from 3,146 PD patients from 6 centers (5 from Europe and 1 from the USA). Statistical analysis was performed using the variable threshold test, and the Mantel-Haenszel procedure was used to estimate odds ratios.RESULTS: Analysis of sequence data from 17,258 individuals demonstrated a significantly higher frequency of ANG variants in both ALS and PD patients compared to control subjects (p = 9.3 × 10(-6) for ALS and p = 4.3 × 10(-5) for PD). The odds ratio for any ANG variant in patients versus controls was 9.2 for ALS and 6.7 for PD.INTERPRETATION: The data from this multicenter study demonstrate that there is a strong association between PD, ALS, and ANG variants. ANG is a genetic link between ALS and PD.
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17. |
- van Setten, Jessica, et al.
(author)
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PR interval genome-wide association meta-analysis identifies 50 loci associated with atrial and atrioventricular electrical activity
- 2018
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In: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 9
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Journal article (peer-reviewed)abstract
- Electrocardiographic PR interval measures atrio-ventricular depolarization and conduction, and abnormal PR interval is a risk factor for atrial fibrillation and heart block. Our genomewide association study of over 92,000 European-descent individuals identifies 44 PR interval loci (34 novel). Examination of these loci reveals known and previously not-yet-reported biological processes involved in cardiac atrial electrical activity. Genes in these loci are overrepresented in cardiac disease processes including heart block and atrial fibrillation. Variants in over half of the 44 loci were associated with atrial or blood transcript expression levels, or were in high linkage disequilibrium with missense variants. Six additional loci were identified either by meta-analysis of similar to 105,000 African and European-descent individuals and/or by pleiotropic analyses combining PR interval with heart rate, QRS interval, and atrial fibrillation. These findings implicate developmental pathways, and identify transcription factors, ionchannel genes, and cell-junction/cell-signaling proteins in atrio-ventricular conduction, identifying potential targets for drug development.
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18. |
- Diekstra, Frank P., et al.
(author)
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C9orf72 and UNC13A Are Shared Risk Loci for Amyotrophic Lateral Sclerosis and Frontotemporal Dementia : A Genome-Wide Meta-Analysis
- 2014
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In: Annals of Neurology. - : John Wiley & Sons. - 0364-5134 .- 1531-8249. ; 76:1, s. 120-133
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Journal article (peer-reviewed)abstract
- Objective: Substantial clinical, pathological, and genetic overlap exists between amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). TDP-43 inclusions have been found in both ALS and FTD cases (FTD-TDP). Recently, a repeat expansion in C9orf72 was identified as the causal variant in a proportion of ALS and FTD cases. We sought to identify additional evidence for a common genetic basis for the spectrum of ALS-FTD. Methods: We used published genome-wide association studies data for 4,377 ALS patients and 13,017 controls, and 435 pathology-proven FTD-TDP cases and 1,414 controls for genotype imputation. Data were analyzed in a joint meta-analysis, by replicating topmost associated hits of one disease in the other, and by using a conservative rank products analysis, allocating equal weight to ALS and FTD-TDP sample sizes. Results: Meta-analysis identified 19 genome-wide significant single nucleotide polymorphisms (SNPs) in C9orf72 on chromosome 9p21.2 (lowest p = 2.6 x 10(-12)) and 1 SNP in UNC13A on chromosome 19p13.11 (p = 1.0 x 10(-11)) as shared susceptibility loci for ALS and FTD-TDP. Conditioning on the 9p21.2 genotype increased statistical significance at UNC13A. A third signal, on chromosome 8q24.13 at the SPG8 locus coding for strumpellin (p = 3.91 x 10(-7)) was replicated in an independent cohort of 4,056 ALS patients and 3,958 controls (p = 0.026; combined analysis p = 1.01 x 10(-7)). Interpretation: We identified common genetic variants in C9orf72, but in addition in UNC13A that are shared between ALS and FTD. UNC13A provides a novel link between ALS and FTD-TDP, and identifies changes in neurotransmitter release and synaptic function as a converging mechanism in the pathogenesis of ALS and FTD-TDP.
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19. |
- Flores, Olivier, et al.
(author)
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An evolutionary perspective on leaf economics : phylogenetics of leaf mass per area in vascular plants
- 2014
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In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:14, s. 2799-2811
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Journal article (peer-reviewed)abstract
- In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This worldwide leaf economics spectrum consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf construction and light-interception borne by plants. We conducted a broad-scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes.
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20. |
- Lagou, Vasiliki, et al.
(author)
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Sex-dimorphic genetic effects and novel loci for fasting glucose and insulin variability
- 2021
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 12:1
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Journal article (peer-reviewed)abstract
- Differences between sexes contribute to variation in the levels of fasting glucose and insulin. Epidemiological studies established a higher prevalence of impaired fasting glucose in men and impaired glucose tolerance in women, however, the genetic component underlying this phenomenon is not established. We assess sex-dimorphic (73,089/50,404 women and 67,506/47,806 men) and sex-combined (151,188/105,056 individuals) fasting glucose/fasting insulin genetic effects via genome-wide association study meta-analyses in individuals of European descent without diabetes. Here we report sex dimorphism in allelic effects on fasting insulin at IRS1 and ZNF12 loci, the latter showing higher RNA expression in whole blood in women compared to men. We also observe sex-homogeneous effects on fasting glucose at seven novel loci. Fasting insulin in women shows stronger genetic correlations than in men with waist-to-hip ratio and anorexia nervosa. Furthermore, waist-to-hip ratio is causally related to insulin resistance in women, but not in men. These results position dissection of metabolic and glycemic health sex dimorphism as a steppingstone for understanding differences in genetic effects between women and men in related phenotypes.
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21. |
- Marschall, Tobias, et al.
(author)
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Computational pan-genomics : status, promises and challenges
- 2018
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In: Briefings in Bioinformatics. - : Oxford University Press (OUP). - 1467-5463 .- 1477-4054. ; 19:1, s. 118-135
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Journal article (peer-reviewed)abstract
- Many disciplines, from human genetics and oncology to plant breeding, microbiology and virology, commonly face the challenge of analyzing rapidly increasing numbers of genomes. In case of Homo sapiens, the number of sequenced genomes will approach hundreds of thousands in the next few years. Simply scaling up established bioinformatics pipelines will not be sufficient for leveraging the full potential of such rich genomic data sets. Instead, novel, qualitatively different computational methods and paradigms are needed. We will witness the rapid extension of computational pan-genomics, a new sub-area of research in computational biology. In this article, we generalize existing definitions and understand a pan-genome as any collection of genomic sequences to be analyzed jointly or to be used as a reference. We examine already available approaches to construct and use pan-genomes, discuss the potential benefits of future technologies and methodologies and review open challenges from the vantage point of the above-mentioned biological disciplines. As a prominent example for a computational paradigm shift, we particularly highlight the transition from the representation of reference genomes as strings to representations as graphs. We outline how this and other challenges from different application domains translate into common computational problems, point out relevant bioinformatics techniques and identify open problems in computer science. With this review, we aim to increase awareness that a joint approach to computational pan-genomics can help address many of the problems currently faced in various domains.
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22. |
- van Battum, P., et al.
(author)
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Differences in minor amputation rate in diabetic foot disease throughout Europe are in part explained by differences in disease severity at presentation
- 2011
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In: Diabetic Medicine. - : Wiley. - 1464-5491 .- 0742-3071. ; 28:2, s. 199-205
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Journal article (peer-reviewed)abstract
- P>Objectives The incidence of minor amputation may vary significantly, and determinants of minor amputation have not been studied systematically. We evaluated minor amputation rate, the determinants of minor amputation and differences in amputation rate between European centres. Methods In the Eurodiale study, a prospective cohort study of 1232 patients (1088 followed until end-point) with a new diabetic foot ulcer were followed on a monthly basis until healing, death, major amputation or up to a maximum of 1 year. Ulcers were treated according to international guidelines. Baseline characteristics independently associated with minor amputation were examined using multiple logistic regression modelling. Based on the results of the multivariable analysis, a disease severity score was calculated for each patient. Results One hundred and ninety-four (18%) patients underwent a minor amputation. Predictors of minor amputation were depth of the ulcer (odds ratio 6.08, confidence interval 4.10-9.03), peripheral arterial disease (odds ratio 1.84, confidence interval 1.30-2.60), infection (odds ratio 1.56, confidence interval 1.05-2.30) and male sex (odds ratio 1.42, confidence interval 0.99-2.04). Minor amputation rate varied between 2.4 and 34% in the centres. Minor amputation rate in centres correlated strongly with disease severity score at the moment of presentation to the foot clinic (r = 0.75). Conclusions Minor amputation is performed frequently in diabetic foot centres throughout Europe and is determined by depth of the ulcer, peripheral arterial disease, infection and male sex. There are important differences in amputation rate between the European centres, which can be explained in part by severity of disease at presentation. This may suggest that early referral to foot clinics can prevent minor amputations.
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23. |
- Bakker, Jan P., et al.
(author)
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Long-term effects of scrub clearance and litter removal on the re-establishment of dry alvar grassland species
- 2012
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In: Annales Botanici Fennici. - 0003-3847 .- 1797-2442. ; 49:1-2, s. 21-30
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Journal article (peer-reviewed)abstract
- Many characteristic dry alvar grassland species disappear after cessation of livestock grazing as a result of encroachment by Juniperus communis. We studied the re-establishment of these species after scrub clearance with and without the removal of the layer of litter and mosses in long-term (14 years) permanent plots. Most of the species belonging to the community species pool of dry alvar grassland species before clearance were found in permanent plots between 2 and 14 years after the clearance. A large part originated from vegetative spread of already occurring species in the established vegetation in the surroundings. Only a small part of the long-term persistent soil seed bank resulted in the re-establishment of alvar species. There was no significant difference in the traits soil seed bank, seed weight and long-distance dispersal by wind, dung or fur of animals of established and non-established species. Removal of litter and mosses positively affected the re-establishment of alvar species.
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24. |
- Bakker, Jan P., et al.
(author)
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Shading results in depletion of the soil seed bank
- 2014
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In: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 32:5, s. 674-679
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Journal article (peer-reviewed)abstract
- To what extent is the decline of characteristic dry alvar species related to the decline in the soil seed bank during scrub encroachment? We recorded the number of flower stems in the vegetation in relation to light attenuation along an encroachment series progressing from open alvar through small gaps inside dense scrub of Juniperus communis (cover of 60%) to intact dense scrub (cover of 100%) on the island of oland, Sweden. This measurement of potential reproduction (number of flower stems) was then compared to the number of species in the soil seed bank at each site along the alvar encroachment series. Scrub encroachment results in light attenuation between and under the shrubs. The total number of flower stems averaged over all species was similar between gaps and open alvar, but that of alvar species was significantly lower in the gaps, indicating that light attenuation could reduce their seed set. Shading in gaps is related to depletion of the soil seed bank and loss of alvar species, particularly those that do not form a persistent soil seed bank.
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25. |
- Game, F. L., et al.
(author)
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A systematic review of interventions to enhance the healing of chronic ulcers of the foot in diabetes
- 2012
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In: Diabetes/Metabolism Research & Reviews. - : Wiley. - 1520-7552. ; 28:Suppl. 1, s. 119-141
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Journal article (peer-reviewed)abstract
- The outcome of management of diabetic foot ulcers is poor, and there is continuing uncertainty concerning optimal approaches to management. It was for these reasons that in 2006 the International Working Group of the Diabetic Foot (IWGDF) working group on wound healing undertook a systematic review of the evidence to inform protocols for routine care and to highlight areas which should be considered for further study. The same working group has now updated this review by considering papers on the interventions to improve the healing of chronic ulcers published between December 2006 and June 2010. Methodological quality of selected studies was independently assessed by two reviewers using Scottish Intercollegiate Guidelines Network criteria. Selected studies fell into the following ten categories: sharp debridement and wound bed preparation with larvae and hydrotherapy; wound bed preparation using antiseptics, applications and dressing products; resection of the chronic wound; hyperbaric oxygen therapy (HBOT); compression or negative pressure therapy; products designed to correct aspects of wound biochemistry and cell biology associated with impaired wound healing; application of cells, including platelets and stem cells; bioengineered skin and skin grafts; electrical, electromagnetic, lasers, shockwaves and ultrasound; other systemic therapies which did not fit in the above categories. Heterogeneity of studies prevented pooled analysis of results. Of the 1322 papers identified, 43 were selected for grading following full text review. The present report is an update of the earlier IWGDF systematic review, but the conclusion is similar: that with the exception of HBOT and, possibly, negative pressure wound therapy, there is little published evidence to justify the use of newer therapies. This echoes the conclusion of a recent Cochrane review and the systematic review undertaken by the National Institute for Health and Clinical Excellence Guidelines Committee in the UK. Analysis of evidence presents considerable difficulties in this field particularly as controlled studies are few and the majority are of poor methodological quality. Copyright (C) 2012 John Wiley & Sons, Ltd.
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26. |
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27. |
- Hinchliffe, R J, et al.
(author)
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A systematic review of the effectiveness of interventions to enhance the healing of chronic ulcers of the foot in diabetes
- 2008
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In: Diabetes/Metabolism Research & Reviews. - : Wiley. - 1520-7552 .- 1520-7560. ; 24:S1, s. 119-144
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Research review (peer-reviewed)abstract
- The outcome of management of diabetic foot ulcers is poor and there is uncertainty concerning optimal approaches to management. We have undertaken a systematic review to identify interventions for which there is evidence of effectiveness. A search was made for reports of the effectiveness of interventions assessed in terms of healing, ulcer area or amputation in controlled clinical studies published prior to December 2006. Methodological quality of selected studies was independently assessed by two reviewers using Scottish Intercollegiate Guidelines Network (SIGN) criteria. Selected studies fell into the following categories: sharp debridement and larvae; antiseptics and dressings; chronic wound resection hyperbaric oxygen (HBO); reduction of tissue oedema; skin grafts; electrical and magnetic stimulation and ultrasound. Heterogeneity of studies prevented pooled analysis of results. Of the 2251 papers identified, 60 were selected for grading following full text review. Some evidence was found to support hydrogels as desloughing agents and to suggest that a systemic (HBO) therapy may be effective. Topical negative pressure (TNP) may promote healing of post-operative wounds, and resection of neuropathic plantar ulcers may be beneficial. More information was needed to confirm the effectiveness and cost-effectiveness of these and other interventions. No data were found to justify the use of any other topically applied product or dressing, including those with antiseptic properties. Further evidence to substantiate the effect of interventions designed to enhance the healing of chronic ulcers is urgently needed. Until such evidence is available from robust trials, there is limited justification for the use of more expensive treatments and dressings.
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28. |
- Hinchliffe, R. J., et al.
(author)
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A systematic review of the effectiveness of revascularization of the ulcerated foot in patients with diabetes and peripheral arterial disease
- 2012
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In: Diabetes/Metabolism Research & Reviews. - : Wiley. - 1520-7552. ; 28:Suppl. 1, s. 179-217
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Journal article (peer-reviewed)abstract
- In several large recent observational studies, peripheral arterial disease (PAD) was present in up to 50% of the patients with a diabetic foot ulcer and was an independent risk factor for amputation. The International Working Group on the Diabetic Foot therefore established a multidisciplinary working group to evaluate the effectiveness of revascularization of the ulcerated foot in patients with diabetes and PAD. A systematic search was performed for therapies to revascularize the ulcerated foot in patients with diabetes and PAD from 1980June 2010. Only clinically relevant outcomes were assessed. The research conformed to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and the Scottish Intercollegiate Guidelines Network methodological scores were assigned. A total of 49 papers were eligible for full text review. There were no randomized controlled trials, but there were three nonrandomized studies with a control group. The major outcomes following endovascular or open bypass surgery were broadly similar among the studies. Following open surgery, the 1-year limb salvage rates were a median of 85% (interquartile range of 8090%), and following endovascular revascularization, these rates were 78% (70.585.5%). At 1-year follow-up, 60% or more of ulcers had healed following revascularization with either open bypass surgery or endovascular revascularization. Studies appeared to demonstrate improved rates of limb salvage associated with revascularization compared with the results of medically treated patients in the literature. There were insufficient data to recommend one method of revascularization over another. There is a real need for standardized reporting of baseline demographic data, severity of disease and outcome reporting in this group of patients. Copyright (C) 2012 John Wiley & Sons, Ltd.
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29. |
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30. |
- McCarthy, Shane, et al.
(author)
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A reference panel of 64,976 haplotypes for genotype imputation
- 2016
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 48:10, s. 1279-1283
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Journal article (peer-reviewed)abstract
- We describe a reference panel of 64,976 human haplotypes at 39,235,157 SNPs constructed using whole-genome sequence data from 20 studies of predominantly European ancestry. Using this resource leads to accurate genotype imputation at minor allele frequencies as low as 0.1% and a large increase in the number of SNPs tested in association studies, and it can help to discover and refine causal loci. We describe remote server resources that allow researchers to carry out imputation and phasing consistently and efficiently.
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31. |
- Prompers, L, et al.
(author)
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Delivery of care to diabetic patients with foot ulcers in daily practice: results of the Eurodiale Study, a prospective cohort study
- 2008
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In: Diabetic Medicine. - : Wiley. - 1464-5491 .- 0742-3071. ; 25:6, s. 700-707
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Journal article (peer-reviewed)abstract
- Aims To determine current management and to identify patient-related factors and barriers that influence management strategies in diabetic foot disease. Methods The Eurodiale Study is a prospective cohort study of 1232 consecutive individuals presenting with a new diabetic foot ulcer in 14 centres across Europe. We determined the use of management strategies: referral, use of offloading, vascular imaging and revascularization. Results Twenty-seven percent of the patients had been treated for > 3 months before referral to a foot clinic. This varied considerably between countries (6-55%). At study entry, 77% of the patients had no or inadequate offloading. During follow-up, casting was used in 35% (0-68%) of the plantar fore- or midfoot ulcers. Predictors of use of casting were male gender, large ulcer size and being employed. Vascular imaging was performed in 56% (14-86%) of patients with severe limb ischaemia; revascularization was performed in 43%. Predictors of use of vascular imaging were the presence of infection and ischaemic rest pain. Conclusion Treatment of many patients is not in line with current guidelines and there are large differences between countries and centres. Our data suggest that current guidelines are too general and that healthcare organizational barriers and personal beliefs result in underuse of recommended therapies. Action should be undertaken to overcome these barriers and to guarantee the delivery of optimal care for the many individuals with diabetic foot disease.
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32. |
- Prompers, L., et al.
(author)
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High prevalence of ischaemia, infection and serious comorbidity in patients with diabetic foot disease in Europe. Baseline results from the Eurodiale study
- 2007
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In: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 50:1, s. 18-25
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Journal article (peer-reviewed)abstract
- Large clinical studies describing the typical clinical presentation of diabetic foot ulcers are limited and most studies were performed in single centres with the possibility of selection of specific subgroups. The aim of this study was to investigate the characteristics of diabetic patients with a foot ulcer in 14 European hospitals in ten countries. The study population included 1,229 consecutive patients presenting with a new foot ulcer between 1 September 2003 and 1 October 2004. Standardised data on patient characteristics, as well as foot and ulcer characteristics, were obtained. Foot disease was categorised into four stages according to the presence or absence of peripheral arterial disease (PAD) and infection: A: PAD -, infection -; B: PAD -, infection +; C: PAD +, infection -; D: PAD +, infection +. PAD was diagnosed in 49% of the subjects, infection in 58%. The majority of ulcers (52%) were located on the non-plantar surface of the foot. With regard to severity, 24% had stage A, 27% had stage B, 18% had stage C and 31% had stage D foot disease. Patients in the latter group had a distinct profile: they were older, had more non-plantar ulcers, greater tissue loss and more serious comorbidity. According to our results in this European cohort, the severity of diabetic foot ulcers at presentation is greater than previously reported, as one-third had both PAD and infection. Non-plantar foot ulcers were more common than plantar ulcers, especially in patients with severe disease, and serious comorbidity increased significantly with increasing severity of foot disease. Further research is needed to obtain insight into the clinical outcome of these patients.
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33. |
- Prompers, L., et al.
(author)
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Prediction of outcome in individuals with diabetic foot ulcers: focus on the differences between individuals with and without peripheral arterial disease. The EURODIALE Study
- 2008
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In: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 51:5, s. 747-755
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Journal article (peer-reviewed)abstract
- Aims/hypothesis Outcome data on individuals with diabetic foot ulcers are scarce, especially in those with peripheral arterial disease (PAD). We therefore examined the clinical characteristics that best predict poor outcome in a large population of diabetic foot ulcer patients and examined whether such predictors differ between patients with and without PAD. Methods Analyses were conducted within the EURODIALE Study, a prospective cohort study of 1,088 diabetic foot ulcer patients across 14 centres in Europe. Multiple logistic regression modelling was used to identify independent predictors of outcome (i.e. non-healing of the foot ulcer). Results After 1 year of follow-up, 23% of the patients had not healed. Independent baseline predictors of non-healing in the whole study population were older age, male sex, heart failure, the inability to stand or walk without help, end-stage renal disease, larger ulcer size, peripheral neuropathy and PAD. When analyses were performed according to PAD status, infection emerged as a specific predictor of non-healing in PAD patients only. Conclusions/Interpretation Predictors of healing differ between patients with and without PAD, suggesting that diabetic foot ulcers with or without concomitant PAD should be defined as two separate disease states. The observed negative impact of infection on healing that was confined to patients with PAD needs further investigation.
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34. |
- Prompers, L., et al.
(author)
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Resource utilisation and costs associated with the treatment of diabetic foot ulcers. Prospective data from the Eurodiale Study
- 2008
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In: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 51:10, s. 1826-1834
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Journal article (peer-reviewed)abstract
- Aims/hypothesis The aim of the present study was to investigate resource utilisation and associated costs in patients with diabetic foot ulcers and to analyse differences in resource utilisation between individuals with or without peripheral arterial disease (PAD) and/or infection. Methods Data on resource utilisation were collected prospectively in a European multicentre study. Data on 1,088 patients were available for the analysis of resource use, and data on 821 patients were included in the costing analysis. Costs were calculated for each patient by multiplying the country-specific direct and indirect unit costs by the number of resources used from inclusion into the study up to a defined endpoint. Country-specific costs were converted into purchasing power standards. Results Resource use and costs varied between outcome groups and between disease severity groups. The highest costs per patient were for hospitalisation, antibiotics, amputations and other surgery. All types of resource utilisation and costs increased with the severity of disease. The total cost per patient was more than four times higher for patients with infection and PAD at inclusion than for patients in the least severe group, who had neither. Conclusions/interpretation Important differences in resource use and costs were found between different patient groups. The costs are highest for individuals with both peripheral arterial disease and infection, and these are mainly related to substantial costs for hospitalisation. In view of the magnitude of the costs associated with in-hospital stay, reducing the number and duration of hospital admissions seems an attractive option to decrease costs in diabetic foot disease.
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35. |
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36. |
- Schaper, N. C., et al.
(author)
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Diagnosis and treatment of peripheral arterial disease in diabetic patients with a foot ulcer. A progress report of the International Working Group on the Diabetic Foot
- 2012
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In: Diabetes/Metabolism Research & Reviews. - : Wiley. - 1520-7552. ; 28:Suppl. 1, s. 218-224
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Journal article (peer-reviewed)abstract
- The International Working Group on the Diabetic Foot (IWDGF) has produced in 2011 a guideline on the diagnosis and treatment of peripheral arterial disease in patients with diabetes and a foot ulcer. This document, together with a systematic review that provided the background information on management, was produced by a multidisciplinary working group of experts in the field and was endorsed by the IWDGF. This progress report is based on these two documents and earlier consensus texts of the IWDGF on the diagnosis and management of diabetic foot ulcers. Its aim is to give the clinician clear guidance on when and how to diagnose peripheral arterial disease in patients with diabetes and a foot ulcer and when and which treatment modalities should be considered, taking both risks and benefits into account. Copyright (C) 2012 John Wiley & Sons, Ltd.
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37. |
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38. |
- Siersma, V., et al.
(author)
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Importance of factors determining the low health-related quality of life in people presenting with a diabetic foot ulcer: the Eurodialestudy
- 2013
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In: Diabetic Medicine. - : Wiley. - 1464-5491 .- 0742-3071. ; 30:11, s. 1382-1387
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Journal article (peer-reviewed)abstract
- AimTo identify the factors responsible for the low health-related quality of life associated with foot ulcers and the relative importance of these factors. MethodsA total of 1232 patients with a new foot ulcer, who presented at one of the 14 centres in 10 European countries participating in the Eurodiale study, were included in this cross-sectional study. Patient and ulcer characteristics were obtained as well as results from the Euro-Qol-5D questionnaire, a health-related quality of life instrument with five domains (mobility, self-care, usual activities, pain/discomfort and anxiety/depression). To analyse the relative importance of comorbidities and ulcer- and patient-related factors for health-related quality of life, linear regression models were used to calculate the relative contributions of each factor to the fit (R-2) of the model. ResultsPatients reported poor overall health-related quality of life, with problems primarily in the mobility and pain/discomfort domains. Among the comorbidities, the inability to stand or walk without help was the most important determinant of decreased health-related quality of life in all five domains. Among ulcer-related factors, ulcer size, limb-threatening ischaemia and elevated C-reactive protein concentration also had high importance in all domains. The clinical diagnosis of infection, peripheral arterial disease and polyneuropathy were only important in the pain/discomfort domain. ConclusionsThe factors that determine health-related quality of life are diverse and to an extent not disease-specific. To improve health-related quality of life, treatment should not only be focused on ulcer healing but a multifactorial approach by a specialized multidisciplinary team is also important. What's new? The inability to stand or walk without help is the most important determinant of poor health-related quality of life. Other factors with high importance are ulcer size, elevated C-reactive protein concentration and limb-threatening ischaemia. To improve health-related quality of life, treatment should not only be focused on ulcer healing but a multifactorial approach by a specialized multidisciplinary team is also important.
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39. |
- Vergoossen, Dana L. E., et al.
(author)
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Enrichment of serum IgG4 in MuSK myasthenia gravis patients
- 2022
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In: Journal of Neuroimmunology. - : Elsevier. - 0165-5728 .- 1872-8421. ; 373
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Journal article (peer-reviewed)abstract
- Muscle-specific kinase (MuSK) myasthenia gravis (MG) is a neuromuscular autoimmune disease belonging to a growing group of IgG4 autoimmune diseases (IgG4-AIDs), in which the majority of pathogenic autoantibodies are of the IgG4 subclass. The more prevalent form of MG with acetylcholine receptor (AChR) antibodies is caused by IgG1-3 autoantibodies. A dominant role for IgG4 in autoimmune disease is intriguing due to its antiinflammatory characteristics. It is unclear why MuSK autoantibodies are predominantly IgG4. We hypothesized that MuSK MG patients have a general predisposition to generate IgG4 responses, therefore resulting in high levels of circulating IgG4. To investigate this, we quantified serum Ig isotypes and IgG subclasses using nephelometric and turbidimetric assays in MuSK MG and AChR MG patients not under influence of immunosuppressive treatment. Absolute serum IgG1 was increased in both MuSK and AChR MG patients compared to healthy donors. In addition, only MuSK MG patients on average had significantly increased and enriched serum IgG4. Although more MuSK MG patients had elevated serum IgG4, for most the IgG4 serum levels fell within the normal range. Correlation analyses suggest MuSK-specific antibodies do not solely explain the variation in IgG4 levels. In conclusion, although serum IgG4 levels are slightly increased, the levels do not support ubiquitous IgG4 responses in MuSK MG patients as the underlying cause of dominant IgG4 MuSK antibodies.
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