Sex differences in clinical characteristics of migraine and its burden: A population-based study

BACKGROUND

Understanding migraine in a sex-specific manner is crucial for improving clinical care, diagnosis, and therapy for both females and males. Here, we provide data on sex differences in the presentation of migraine in a large European-based population cohort, which is representative of the general population.

METHODS

We performed a population-based study of 62,672 Danish blood donors (both present and previous donors), of whom 12,658 had migraine. All participants completed a 105-item diagnostic migraine questionnaire send via electronic mailing system (e-Boks) between May 2020 and August 2020. The questionnaire allowed for correct diagnosis of migraine according to the International Classification of Headache Disorders third edition.

RESULTS

The migraine questionnaire was in-cohort validated and had a positive predictive value of 97% for any migraine, a specificity of 93%, and a sensitivity of 93%. There were 9,184 females (mean age=45.1) and 3,434 males (mean age=48.0). The three-months prevalence of migraine without aura was 11% in females and 3.59% in males. The three-months prevalence of migraine with aura was 1.72% in females and 1.58% in males. In females, the age-related three-months prevalence of migraine without aura increased markedly during the childbearing age. In males, both migraine with- and without aura showed less age variation. Females had a higher frequency of migraine attacks (OR=1.22), but a lower frequency of non-migraine headaches (OR=0.35). Females also had a greater intensity of pain, more unilateral and pulsatile pain, and exacerbation by physical activity (OR=1.40-1.49) as well as more associated symptoms (OR=1.26-1.98). Females carried 79% of the total migraine disease burden, which was almost exclusively driven by migraine without aura (77%), while there was no sex difference in the disease burden of migraine with aura.

CONCLUSION

Females have more severe disease, resulting in a much higher migraine disease burden than indicated by prevalence alone.

The genetic basis of endometriosis and comorbidity with other pain and inflammatory conditions

Endometriosis is a common condition associated with debilitating pelvic pain and infertility. A genome-wide association study meta-analysis, including 60,674 cases and 701,926 controls of European and East Asian descent, identified 42 genome-wide significant loci comprising 49 distinct association signals. Effect sizes were largest for stage 3/4 disease, driven by ovarian endometriosis. Identified signals explained up to 5.01% of disease variance and regulated expression or methylation of genes in endometrium and blood, many of which were associated with pain perception/maintenance (SRP14/BMF, GDAP1, MLLT10, BSN and NGF). We observed significant genetic correlations between endometriosis and 11 pain conditions, including migraine, back and multisite chronic pain (MCP), as well as inflammatory conditions, including asthma and osteoarthritis. Multitrait genetic analyses identified substantial sharing of variants associated with endometriosis and MCP/migraine. Targeted investigations of genetically regulated mechanisms shared between endometriosis and other pain conditions are needed to aid the development of new treatments and facilitate early symptomatic intervention.

A saturated map of common genetic variants associated with human height

Common single-nucleotide polymorphisms (SNPs) are predicted to collectively explain 40-50% of phenotypic variation in human height, but identifying the specific variants and associated regions requires huge sample sizes1. Here, using data from a genome-wide association study of 5.4 million individuals of diverse ancestries, we show that 12,111 independent SNPs that are significantly associated with height account for nearly all of the common SNP-based heritability. These SNPs are clustered within 7,209 non-overlapping genomic segments with a mean size of around 90 kb, covering about 21% of the genome. The density of independent associations varies across the genome and the regions of increased density are enriched for biologically relevant genes. In out-of-sample estimation and prediction, the 12,111 SNPs (or all SNPs in the HapMap 3 panel2) account for 40% (45%) of phenotypic variance in populations of European ancestry but only around 10-20% (14-24%) in populations of other ancestries. Effect sizes, associated regions and gene prioritization are similar across ancestries, indicating that reduced prediction accuracy is likely to be explained by linkage disequilibrium and differences in allele frequency within associated regions. Finally, we show that the relevant biological pathways are detectable with smaller sample sizes than are needed to implicate causal genes and variants. Overall, this study provides a comprehensive map of specific genomic regions that contain the vast majority of common height-associated variants. Although this map is saturated for populations of European ancestry, further research is needed to achieve equivalent saturation in other ancestries.

The association between water hardness and xerosis-Results from the Danish Blood Donor Study

BACKGROUND

The pathophysiology of xerosis depends on extrinsic and intrinsic exposures. Residential hard water may constitute such an exposure.

OBJECTIVES

To estimate the prevalence of xerosis and to compare water hardness exposure in blood donors with and without xerosis.

METHODS

In this retrospective cohort study in 2018-2019, blood donors with self-reported moderately or severely dry skin were compared to blood donors without dry skin. Blood donors with ichthyosis, lichen planus and psoriasis were excluded. Water hardness data was collected from the Geology Survey of Denmark and Greenland.

RESULTS

Overall, 4,748 of 30,721 (15.5%; 95% confidence interval 15.1-15.9%) blood donors had xerosis. After excluding blood donors with ichthyosis, lichen planus and psoriasis, 4,416 blood donors (2,559 females; median age 38.4 years [interquartile range 28.0-49.8]; 700 smokers) remained in this study. Water softer than 12-24 degrees Deutsche härte was associated with decreased probability of xerosis (odds ratio 0.83; 95% confidence interval 0.74-0.94) and water harder than 12-24 degrees Deutsche härte was associated with increased probability of xerosis (odds ratio 1.22; 95% confidence interval 1.03-1.45). The association between water hardness and xerosis remained significant after excluding blood donors with dermatitis.

CONCLUSIONS

Water hardness is associated with xerosis independent of other dermatoses.

Genetic insight into sick sinus syndrome

Aims

The aim of this study was to use human genetics to investigate the pathogenesis of sick sinus syndrome (SSS) and the role of risk factors in its development.

Methods and results

We performed a genome-wide association study of 6469 SSS cases and 1 000 187 controls from deCODE genetics, the Copenhagen Hospital Biobank, UK Biobank, and the HUNT study. Variants at six loci associated with SSS, a reported missense variant in MYH6, known atrial fibrillation (AF)/electrocardiogram variants at PITX2, ZFHX3, TTN/CCDC141, and SCN10A and a low-frequency (MAF = 1.1–1.8%) missense variant, p.Gly62Cys in KRT8 encoding the intermediate filament protein keratin 8. A full genotypic model best described the p.Gly62Cys association (P = 1.6 × 10⁻²⁰), with an odds ratio (OR) of 1.44 for heterozygotes and a disproportionally large OR of 13.99 for homozygotes. All the SSS variants increased the risk of pacemaker implantation. Their association with AF varied and p.Gly62Cys was the only variant not associating with any other arrhythmia or cardiovascular disease. We tested 17 exposure phenotypes in polygenic score (PGS) and Mendelian randomization analyses. Only two associated with the risk of SSS in Mendelian randomization, AF, and lower heart rate, suggesting causality. Powerful PGS analyses provided convincing evidence against causal associations for body mass index, cholesterol, triglycerides, and type 2 diabetes (P > 0.05).

Conclusion

We report the associations of variants at six loci with SSS, including a missense variant in KRT8 that confers high risk in homozygotes and points to a mechanism specific to SSS development. Mendelian randomization supports a causal role for AF in the development of SSS.

Epidemiology of Hyperhidrosis in Danish Blood Donors

The risk factors and disease implications of hyper-hidrosis are unknown. The objectives of this retrospective cohort study were to estimate the prevalence of hyperhidrosis and to compare demographic, life-style, and socioeconomic parameters in blood donors with and without self-reported or hospital-diagnosed hyperhidrosis. The study included blood donors from the Danish Blood Donor Study for the period 2010-2019. Registry data were collected from Statistics Denmark. Overall, 2,794 of 30,808 blood donors (9.07%; 95% confidence interval (95% CI) 8.75-9.40) had self- reported hyperhidrosis and 284 of 122,225 (0.23%; 95% CI 0.21-0.26) had hospital-diagnosed hyperhidrosis. Self-reported hyperhidrosis was associated with smoking (odds ratio (OR) 1.17; 95% CI 1.05-1.31), overweight (OR 1.72; 95% CI 1.58-1.87), "unemployed" (OR 1.60; 95% CI 1.24-2.08), "short education" (OR 0.76; 95% CI 0.64-0.90), and lower income (beta-coefficient -26,121; 95% CI -37,931, -14,311). Hospital-diagnosed hyperhidrosis did not differ from controls. Thus, self-reported hyperhidrosis was associated with potential hyperhidrosis risk factors (smoking, overweight) and disease implications (unemployment, low education level and income).

Association of proton pump inhibitor and histamine H2-receptor antagonists with restless legs syndrome

Restless legs syndrome (RLS) is a common sensorimotor disorder, which can disrupt sleep and is thought to be caused in part by low cellular iron stores. Proton pump inhibitors (PPI) and histamine H₂-receptor antagonists (H₂A) are among the most commonly used drugs worldwide and show evidence of causing iron deficiency. We conducted a case/non-case observational study of blood donors in the United States (N = 13,403; REDS-III) and Denmark (N = 50,323; Danish Blood Donor Study, DBDS), both of which had complete blood count measures and a completed RLS assessment via the Cambridge–Hopkins RLS questionnaire. After adjusting for age, sex, race, BMI, blood donation frequency, smoking, hormone use, and iron supplement use, PPI/H₂A use was associated with RLS (odds ratio [OR] = 1.41; 95% confidence interval [CI], 1.13–1.76; p = 0.002) in REDS-III for both PPI (OR = 1.43; CI, 1.03–1.95; p = 0.03) and H₂A (OR = 1.56; CI, 1.10–2.16; p = 0.01). DBDS exhibited a similar association with PPIs/H₂As (OR = 1.29; CI, 1.20–1.40; p < 0.001), and for PPIs alone (OR = 1.27; CI, 1.17–1.38; p < 0.001), but not H₂As alone (OR = 1.18; CI, 0.92–1.53; p = 0.2). We found no evidence of blood iron stores mediating this association. The association of PPI, and possibly H₂A, consumption with RLS independent of blood iron status and other factors which contribute to RLS risk suggest the need to re-evaluate use of PPI/H₂A in populations at particular risk for RLS.

A genome-wide meta-analysis yields 46 new loci associating with biomarkers of iron homeostasis

Iron is essential for many biological functions and iron deficiency and overload have major health implications. We performed a meta-analysis of three genome-wide association studies from Iceland, the UK and Denmark of blood levels of ferritin (N = 246,139), total iron binding capacity (N = 135,430), iron (N = 163,511) and transferrin saturation (N = 131,471). We found 62 independent sequence variants associating with iron homeostasis parameters at 56 loci, including 46 novel loci. Variants at DUOX2, F5, SLC11A2 and TMPRSS6 associate with iron deficiency anemia, while variants at TF, HFE, TFR2 and TMPRSS6 associate with iron overload. A HBS1L-MYB intergenic region variant associates both with increased risk of iron overload and reduced risk of iron deficiency anemia. The DUOX2 missense variant is present in 14% of the population, associates with all iron homeostasis biomarkers, and increases the risk of iron deficiency anemia by 29%. The associations implicate proteins contributing to the main physiological processes involved in iron homeostasis: iron sensing and storage, inflammation, absorption of iron from the gut, iron recycling, erythropoiesis and bleeding/menstruation.

Large genome-wide association study identifies three novel risk variants for restless legs syndrome

Restless legs syndrome (RLS) is a common neurological sensorimotor disorder often described as an unpleasant sensation associated with an urge to move the legs. Here we report findings from a meta-analysis of genome-wide association studies of RLS including 480,982 Caucasians (cases = 10,257) and a follow up sample of 24,977 (cases = 6,651). We confirm 19 of the 20 previously reported RLS sequence variants at 19 loci and report three novel RLS associations; rs112716420-G (OR = 1.25, P = 1.5 × 10-18), rs10068599-T (OR = 1.09, P = 6.9 × 10-10) and rs10769894-A (OR = 0.90, P = 9.4 × 10-14). At four of the 22 RLS loci, cis-eQTL analysis indicates a causal impact on gene expression. Through polygenic risk score for RLS we extended prior epidemiological findings implicating obesity, smoking and high alcohol intake as risk factors for RLS. To improve our understanding, with the purpose of seeking better treatments, more genetics studies yielding deeper insights into the disease biology are needed.

Compartmental immunophenotyping in COVID-19 ARDS: A case series

Background

Severe immunopathology may drive the deleterious manifestations that are observed in the advanced stages of coronavirus disease 2019 (COVID-19) but are poorly understood.

Objective

Our aim was to phenotype leukocyte subpopulations and the cytokine milieu in the lungs and blood of critically ill patients with COVID-19 acute respiratory distress syndrome (ARDS).

Methods

We consecutively included patients less than 72 hours after intubation following informed consent from their next of kin. Bronchoalveolar lavage fluid was evaluated by microscopy; bronchoalveolar lavage fluid and blood were assessed by 10-color flow cytometry and a multiplex cytokine panel.

Results

Four mechanically ventilated patients (aged 40-75 years) with moderate-to-severe COVID-19 ARDS were included. Immature neutrophils dominated in both blood and lungs, whereas CD4 and CD8 T-cell lymphopenia was observed in the 2 compartments. However, regulatory T cells and T_H17 cells were found in higher fractions in the lung. Lung CD4 and CD8 T cells and macrophages expressed an even higher upregulation of activation markers than in blood. A wide range of cytokines were expressed at high levels both in the blood and in the lungs, most notably, IL-1RA, IL-6, IL-8, IP-10, and monocyte chemoattactant protein-1, consistent with hyperinflammation.

Conclusion

COVID-19 ARDS exhibits a distinct immunologic profile in the lungs, with a depleted and exhausted CD4 and CD8 T-cell population that resides within a heavily hyperinflammatory milieu.

Cytokine Autoantibodies Are Associated with Infection Risk and Self-Perceived Health: Results from the Danish Blood Donor Study

The presence of naturally occurring cytokine-specific autoantibodies (c-aAb) in humans is well established, as well as associations to selected pathologies. However, the overall influence of c-aAb on immunocompetence remains largely unknown. In this paper, we performed a large-scale investigation of c-aAb association with infection risk. A cohort of healthy Danish blood donors was screened for c-aAb against IL-1α, IL-6, IL-10, IFNα, and GM-CSF using a Luminex-based multiplex assay, and results were linked to data from the Danish National Prescription Registry. The filing of an antimicrobial prescription following c-aAb measurement was used as a proxy for impaired immunocompetence. We found that c-aAb against pro-inflammatory cytokines IFNα and GM-CSF tended to associate with increased risk of prescription filings in women, whereas antibodies against anti-inflammatory IL-10 were associated with a lower predicted risk of antimicrobial prescriptions, as well as higher self-perceived health scores. We also observed an association of cumulative c-aAb presence with prescription risk. Our data show that cytokine autoantibodies in healthy individuals associate with various proxies for immunomodulation, with the exact association dependent on the pattern of pro- or anti-inflammatory cytokines targeted. This suggests that c-aAb may express cytokine-modulatory properties in healthy individuals and may be critical to further investigate as biomarkers of immunodeficiency.

Herpes Simplex Virus Type 1 infection is associated with suicidal behavior and first registered psychiatric diagnosis in a healthy population

Increasing evidence shows that latent infections and inflammation is associated with cognitive and behavioral changes in humans. This case-control study investigates the association between Herpes Simplex Virus Type 1 (HSV-1) infection and C-reactive Protein (CRP) levels, and psychiatric disorders and suicidal behavior. Public health register data from 81,912 participants in the Danish Blood Donor Study, were reviewed to identify individuals registered with an ICD-10 code of any psychiatric diagnosis, or who had attempted or committed suicide. We found 1,504 psychiatric cases and 353 suicidal cases; for all cases, controls were frequency-matched by age and sex, resulting in 5,336 participants. Plasma samples were analyzed for IgG-class antibodies against HSV-1 and CRP. HSV-1 infection was associated with suicidal behavior (odds-ratio, 1.40; 95% confidence interval [CI] 1.11-1.77). Accounting for temporality, HSV-1 infection was associated with having first psychiatric disorder after the date of blood collection (incidence rate ration, 1.44; 95% CI, 1.05-1.95). No association between CRP and psychiatric disorders or suicidal behavior was found. The finding that HSV-1 was associated with suicidal behavior and first psychiatric disorder indicates that infection may play a role in the etiology and pathogenesis of suicidal behavior and development of psychiatric disorders.

Genetic factors influencing hemoglobin levels in 15,567 blood donors: results from the Danish Blood Donor Study

BACKGROUND

Blood donors have an increased risk of low hemoglobin (Hb) levels due to iron deficiency. Therefore, knowledge of genetic variants associated with low Hb could facilitate individualized donation intervals. We have previously reported three specific single-nucleotide polymorphisms that were associated with ferritin levels in blood donors. In this study, we investigated the effect of these single-nucleotide polymorphisms on Hb levels in 15,567 Danish blood donors.

STUDY DESIGN AND METHODS

We studied 15,567 participants in the Danish Blood Donor Study. The examined genes and single-nucleotide polymorphisms were 1) TMPRSS6, involved in regulation of hepcidin: rs855791; 2) HFE, associated with hemochromatosis: rs1800562 and rs1799945; 3) BTBD9, associated with restless leg syndrome: rs9357271; and 4) TF, encoding transferrin: rs2280673 and rs1830084. Associations with Hb levels and risk of Hb deferral were assessed in multivariable linear and logistic regression models.

RESULTS

The HFE,rs1800562 G-allele and the HFE rs1799945 C-allele were associated with lower Hb levels in men and women, and with an increased risk of Hb below 7.8 mmol/L (12.5 g/dL) in women. Only the rs1799945 C-allele increased the risk of Hb below 8.4 mmol/L (13.5 g/dL) in men. In TMPRSS6, the rs855791 T-allele was associated with lower Hb levels in both men and women, and with an increased risk of low Hb among women.

CONCLUSION

With this study we demonstrate that HFE and TMPRSS6 are associated with Hb levels and risk of Hb below the limit of deferral. Thus, genetic testing may be useful in a future assay for personalized donation intervals.

Prevalence of patients with self-reported hidradenitis suppurativa in a cohort of Danish blood donors: a cross-sectional study

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease characterized by recurrent inflamed nodules. No pathognomonic test is available for HS; hence the diagnosis is based on three clinical criteria.

OBJECTIVES

To estimate the cross-sectional prevalence and characterize patients with HS in the Danish Blood Donor Study cohort.

METHODS

A questionnaire previously developed containing HS screening questions, the Major Depression Inventory, the Short Form-12, as well as questions about height, weight and drinking habits was answered by 27 765 blood donors.

RESULTS

The prevalence of HS was 1·8% [95% confidence interval (CI) 1·6-2·0%] in the cohort of Danish blood donors. Donors with HS were on average 4·7 years younger (P < 0·001), had 1·3 kg m^-2 higher mean body mass index (BMI) (P < 0·001) and were significantly more likely to smoke [odds ratio (OR) 1·44, 17·9% vs. 13·1%, P = 0·002] compared with donors without HS. Furthermore, significantly more donors with HS were classified as having moderate depression (3·2% vs. 0·7%, P < 0·001). Also, significantly more patients with HS were apprenticeship educated, received educational support and sickness or cash benefits.

CONCLUSIONS

The prevalence of HS in the cohort of blood donors was estimated to 1·8% (95% CI 1·6-2·0%). Donors with HS reported characteristics similar to those reported for hospital-based patients with HS such as higher BMI, smoking rates and lower socioeconomic status than donors without HS.

Restless legs syndrome is associated with increased risk of migraine

Migraine and restless legs syndrome (RLS) are common disorders that are associated with a high level of individual suffering and major comorbidities. The aetiologies of the disorders are largely unknown, although both migraine and RLS have been linked to disturbances in the dopaminergic system and sleep issues, suggesting a relationship between the disorders. This study examines the association between RLS and migraine in a large population of otherwise healthy adults who are not taking medication. Cross-sectional study that included 20,938 participants enrolled in the Danish Blood Donor Study from 1 May 2015 to 1 February 2017. The study included complete information on migraines, the Cambridge-Hopkins RLS questionnaire, the Major Depression Inventory Scale, sex, age, body mass index (BMI), educational level, smoking status and alcohol consumption. Associations between RLS and migraine, with and without aura, were examined using multivariable logistic regression analysis. Among the participants, 4827 were self-reported migraine sufferers and 1091 were classified as suffering from RLS. Individuals with RLS had an increased risk of migraine compared to non-RLS sufferers, with an odds ratio (OR) = 1.52 (95% confidence interval: 1.33–1.73). For the investigated subtypes of migraine, this association was found to be OR = 1.55 (1.31–1.83) for migraines with aura and OR = 1.29 (1.09–1.52) for migraines without aura. We found a significantly increased occurrence of migraine in individuals with RLS. This risk was independent of sex, age, BMI, educational level, smoking status, alcohol consumption and depressive disorder. Our findings suggest that RLS and migraine may have a common aetiology.

Restless legs syndrome is associated with major comorbidities in a population of Danish blood donors

BACKGROUND

Restless Legs Syndrome (RLS) is characterized by uncomfortable nocturnal sensations in the legs making sedentary activities and sleep difficult, and is thus linked with psychosocial distress. Due to the symptomatology and neurobiology of RLS (disrupting brain iron and dopamine) it is likely that RLS associates with poorer health-related quality of life (HRQL) and depressive disorder. The objective of this study was to investigate the RLS-HRQL and the RLS-depressive disorder links in a generally healthy population that is not biased by medications.

METHODS

Complete data, including the Cambridge-Hopkins RLS questionnaire, the 12-item short-form standardized health survey (SF-12), the Major Depression Inventory (MDI), body mass index, smoking status, alcohol consumption, and education were available for 24,707 participants enrolled in the Danish Blood Donor Study from May 1, 2015 to February 1, 2017. Information on quality of sleep was available for all RLS cases. T-tests and multivariable logistic regression models were applied to examine the associations of RLS and MDI scores, and the physical and mental component scores (PCS and MCS) of SF-12, respectively. Analyses were conducted separately for men and women.

RESULTS

RLS associated with poorer MCS and poorer PCS. Moreover, Participants with RLS were more likely to classify with depressive disorder. Poor quality of sleep was associated with depressive disorder and poorer MCS among RLS cases, and with poorer PCS in female RLS cases.

CONCLUSION

Thus, we demonstrated that RLS is associated with a significantly lower HRQL and a higher prevalence of depressive disorder among otherwise healthy individuals.

Stakeholders in psychiatry and their attitudes toward receiving pertinent and incident findings in genomic research

Increasingly more psychiatric research studies use whole genome sequencing or whole exome sequencing. Consequently, researchers face difficult questions, such as which genomic findings to return to research participants and how. This study aims to gain more knowledge on the attitudes among potential research participants and health professionals toward receiving pertinent and incidental findings. A cross-sectional online survey was developed to investigate the attitudes among research participants toward receiving genomic findings. A total of 2,637 stakeholders responded: 241 persons with mental disorders, 671 relatives, 1,623 blood donors, 74 psychiatrists, and 28 clinical geneticists. Stakeholders wanted both pertinent findings (95%) and incidental findings (91%) to be made available for research participants. The majority (77%) stated that researchers should not actively search for incidental findings. Persons with mental disorders and relatives were generally more positive about receiving any kind of findings than clinical geneticists and psychiatrists. Compared with blood donors, persons with mental disorders reported to be more positive about receiving raw genomic data and information that is not of serious health importance. Psychiatrists and clinical geneticists were less positive about receiving genomic findings compared with blood donors. The attitudes toward receiving findings were very positive. Stakeholders were willing to refrain from receiving incidental information if it could compromise the research. Our results suggest that research participants consider themselves as altruistic participants. This study offers valuable insight, which may inform future programs aiming to develop new strategies to target issues relating to the return of findings in genomic research.

Digital questionnaire platform in the Danish Blood Donor Study

OBJECTIVES

The Danish Blood Donor Study (DBDS) is a prospective, population-based study and biobank. Since 2010, 100,000 Danish blood donors have been included in the study. Prior to July 2015 all participating donors had to complete a paper-based questionnaire. Here we describe the establishment of a digital tablet-based questionnaire platform implemented in blood bank sites across Denmark.

METHODS

The digital questionnaire was developed using the open source survey software tool LimeSurvey. The participants accesses the questionnaire online with a standard SSL encrypted HTTP connection using their personal civil registration numbers. The questionnaire is placed at a front-end web server and a collection server retrieves the completed questionnaires. Data from blood samples, register data, genetic data and verification of signed informed consent are then transferred to and merged with the questionnaire data in the DBDS database.

RESULTS

The digital platform enables personalized questionnaires, presenting only questions relevant to the specific donor by hiding unneeded follow-up questions on screening question results. New versions of questionnaires are immediately available at all blood collection facilities when new projects are initiated.

CONCLUSION

The digital platform is a faster, cost-effective and more flexible solution to collect valid data from participating donors compared to paper-based questionnaires. The overall system can be used around the world by the use of Internet connection, but the level of security depends on the sensitivity of the data to be collected.

Roux-en-Y gastric bypass surgery of morbidly obese patients induces swift and persistent changes of the individual gut microbiota

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is an effective means to achieve sustained weight loss for morbidly obese individuals. Besides rapid weight reduction, patients achieve major improvements of insulin sensitivity and glucose homeostasis. Dysbiosis of gut microbiota has been associated with obesity and some of its co-morbidities, like type 2 diabetes, and major changes of gut microbial communities have been hypothesized to mediate part of the beneficial metabolic effects observed after RYGB. Here we describe changes in gut microbial taxonomic composition and functional potential following RYGB.

METHODS

We recruited 13 morbidly obese patients who underwent RYGB, carefully phenotyped them, and had their gut microbiomes quantified before (n = 13) and 3 months (n = 12) and 12 months (n = 8) after RYGB. Following shotgun metagenomic sequencing of the fecal microbial DNA purified from stools, we characterized the gut microbial composition at species and gene levels followed by functional annotation.

RESULTS

In parallel with the weight loss and metabolic improvements, gut microbial diversity increased within the first 3 months after RYGB and remained high 1 year later. RYGB led to altered relative abundances of 31 species (P < 0.05, q < 0.15) within the first 3 months, including those of Escherichia coli, Klebsiella pneumoniae, Veillonella spp., Streptococcus spp., Alistipes spp., and Akkermansia muciniphila. Sixteen of these species maintained their altered relative abundances during the following 9 months. Interestingly, Faecalibacterium prausnitzii was the only species that decreased in relative abundance. Fifty-three microbial functional modules increased their relative abundance between baseline and 3 months (P < 0.05, q < 0.17). These functional changes included increased potential (i) to assimilate multiple energy sources using transporters and phosphotransferase systems, (ii) to use aerobic respiration, (iii) to shift from protein degradation to putrefaction, and (iv) to use amino acids and fatty acids as energy sources.

CONCLUSIONS

Within 3 months after morbidly obese individuals had undergone RYGB, their gut microbiota featured an increased diversity, an altered composition, an increased potential for oxygen tolerance, and an increased potential for microbial utilization of macro- and micro-nutrients. These changes were maintained for the first year post-RYGB.

TRIAL REGISTRATION

Current controlled trials (ID NCT00810823 , NCT01579981 , and NCT01993511 ).

No association between rs6897932 in the gene encoding interleukin-7 receptor α and low-grade inflammation or self-reported health - results from the Danish Blood Donor Study

The T-allele in the single nucleotide polymorphism rs6897932 in the gene encoding the IL-7 receptor α (IL7RA) is associated with reduced risk of autoimmune diseases including multiple sclerosis and also affects the course of HIV infection. Low-grade inflammation (LGI) and self-reported, health-related quality of life (HRQL) are often associated with chronic diseases and widely used in assessing and monitoring health status. The aim of the present study was to evaluate whether the T-allele in rs6897932 is associated with reduced risk of LGI (hsCRP 3-10 mg/L), history of infectious mononucleosis (IM), and HRQL in healthy individuals. A total of 17, 293 healthy Danish individuals from the Danish Blood Donor Study were included in the analyses. We tested rs6897932 as a predictor of LGI, self-reported IM, and HRQL in univariable and multivariable models stratified by sex. No associations between rs6897932 and LGI, self-reported IM or HRQL were found in men or women. This suggests that rs6897932 is not associated with general inflammation, and the reported associations between the T-allele in rs6897932 with several autoimmune diseases may be mediated through effects on a restricted part of the immune system.

Association studies of novel obesity-related gene variants with quantitative metabolic phenotypes in a population-based sample of 6,039 Danish individuals

AIMS/HYPOTHESIS

Genome-wide association studies have identified novel WHR and BMI susceptibility loci. The aim of this study was to elucidate if any of these loci had an effect on quantitative measures of glucose homeostasis, including estimates of insulin release and insulin sensitivity in an epidemiological setting.

METHODS

By applying an additive genetic model, 14 WHR-associated gene variants and 18 BMI-associated variants were investigated for their relationships with glucose-related metabolic traits in treatment-naive individuals from the population-based Inter99 study sample (n = 6,039).

RESULTS

Of the variants associated with BMI, the QPCTL rs2287019 C allele was associated with an increased insulinogenic index of 7.4% per risk allele (p = 4.0 × 10⁻⁷) and increased disposition index of 5.6% (p = 6.4 × 10⁻⁵). The LRP1B rs2890652 C allele was associated with insulin resistance, showing a 3.3% increase (p = 0.0011) using the HOMA-insulin resistance (HOMA-IR) index and a 2.2% reduction (p = 0.0014) with the Matsuda index. Of the variants associated with WHR, LYPLAL1/SLC30A10 rs4846567 G allele carriers showed a 5.2% lower HOMA-IR (p = 0.00086) in women, indicating improved insulin sensitivity. Female carriers of the VEGFA rs6905288 A allele were insulin resistant, with a 3.7% increase in HOMA-IR (p = 0.00036) and 4.0% decrease in Matsuda index (p = 2 × 10⁻⁴).

CONCLUSIONS

Our correlative findings from analysing single-locus data suggest that some variation in validated BMI and WHR loci are associated with either increased or decreased insulin sensitivity and thereby potentially with metabolically healthy or metabolically unhealthy subsets of obesity. The results call for testing in larger study samples and for further physiological exploration of the possible metabolic implications of these loci.

Variation in the gene encoding Krüppel-like factor 7 influences body fat: studies of 14 818 Danes

OBJECTIVE

KLF7 encodes Krüppel-like factor (KLF) 7, a member of the KLF family of transcription factors, initially shown to play important roles in cellular development and differentiation, and reported to be specifically involved in adipogenesis. Several single nucleotide polymorphisms (SNPs) have been identified in KLF7, of which the A-allele of rs2302870 has been associated with type 2 diabetes in a Japanese population; however, a possible association of KLF7 SNPs with obesity has not been investigated. We aimed to identify variation in the putative promoter region, the coding regions, exon/intron boundaries, and 3'-UTR of KLF7, and to examine identified variants in relation to obesity, type 2 diabetes, and related quantitative traits in Danish individuals.

METHODS

Identified variants were investigated for association with type 2 diabetes in 8777 individuals and with obesity in 14 818 individuals.

RESULTS

We identified four common SNPs in low pairwise linkage disequilibrium; three in the putative promoter region (-1119 G>A, -963 C>A (rs7568369), and -614 G>A) and IVS2+35092 A>C (rs2302870). We failed to confirm an association between rs2302870 and type 2 diabetes. Neither was rs7568369 associated with type 2 diabetes; however, the minor A-allele of rs7568369 protected against obesity (OR=0.90 (0.84-0.96), P=0.001) and in studies of quantitative traits (n=5,535) the variant associated with decreased body mass index (P=0.002) and waist circumference (P=0.003). The -1119 G>A and -614 G>A variants were not associated with obesity or type 2 diabetes.

CONCLUSION

We identified a novel association between the minor A-allele of KLF7 rs7568369 and protection against obesity in the Danish population.

The GCKR rs780094 polymorphism is associated with elevated fasting serum triacylglycerol, reduced fasting and OGTT-related insulinaemia, and reduced risk of type 2 diabetes

AIMS/HYPOTHESIS

Recent genome-wide association studies have suggested that a polymorphism in GCKR, the gene encoding the glucokinase regulatory protein, is involved in triacylglycerol regulation. Our aim was to examine in large-scale studies the common GCKR rs780094 polymorphism in relation to metabolic traits (mainly fasting hypertriacylglycerolaemia) and traits related to pancreatic beta cell function.

METHODS

The polymorphism was genotyped in 16,853 Danes using Taqman allelic discrimination. Association was analysed in case-control studies and quantitative trait analyses. We also analysed the possible interactive effect between the GCK -30G>A polymorphism and the GCKR rs780094 variant on metabolic traits.

RESULTS

The minor GCKR A-allele of rs780094 is associated with an increased level of fasting serum triacylglycerol (p = 6 x 10(-14)), impaired fasting (p = 0.001) and OGTT-related insulin release (p = 3 x 10(-6)), reduced homeostasis model assessment of insulin resistance (p = 0.0004), WHO-defined dyslipidaemia (p = 6 x 10(-9)) and a modestly decreased risk of type 2 diabetes (p = 0.01). Significantly increased fasting serum insulin concentrations were demonstrated when analysing the GCK -30A and GCKR rs780094 G-alleles in an additive model.

CONCLUSIONS/INTERPRETATION

The GCKR rs780094 polymorphism, or another variant with which it is in tight linkage disequilibrium, is likely to increase glucokinase regulatory protein activity to induce improved glycaemic regulation at the expense of hypertriacylglycerolaemia as reflected in the present study of 16,853 Danes. We also suggest an additive effect of GCK and GCKR risk alleles on [corrected] serum insulin release.

Studies of the associations between functional beta2-adrenergic receptor variants and obesity, hypertension and type 2 diabetes in 7,808 white subjects

AIMS/HYPOTHESIS

Functional and common Arg16Gly and Gln27Glu polymorphisms have been identified in ADRB2, the gene encoding the beta2-adrenergic receptor. These variants have previously been examined for association with obesity, hypertension and diabetes with inconclusive results.

MATERIALS AND METHODS

We investigated both of these variants in 7,808 unrelated, middle-aged white people for their association with obesity in a case-control study, quantitative trait analysis and meta-analysis. Moreover, both variants were investigated for their potential influence on measures of hypertension and type 2 diabetes by case-control and quantitative trait analyses.

RESULTS

The present study did not find consistent evidence for an association of these beta2-adrenergic receptor variants with obesity or hypertension; neither did the quantitative trait analyses show any effect of the variants on obesity-related traits. However, both the Gly allele of the Arg16Gly variant and the Glu allele of the Gln27Glu variant showed nominal association with systolic blood pressure. Furthermore, there was a nominal association of the Arg16 allele frequency and genotype distribution with type 2 diabetes; however, no influence on quantitative biochemical phenotypes related to type 2 diabetes was found. A nominal association of the Arg/Gly genotype with the metabolic syndrome was also observed (p=0.003). Logistic regression analyses provided no evidence of a synergistic or an additive effect of these variants on obesity, hypertension or diabetes.

CONCLUSIONS/INTERPRETATION

After studying 7,808 middle-aged white subjects, we were unable to demonstrate any consistent associations between two common amino acid polymorphisms of the beta2-adrenergic receptor and obesity, hypertension or type 2 diabetes.