Genetic variability in exon 1 of the glucocorticoid receptor gene NR3C1 is associated with postoperative complications.

Patients undergoing major surgery experience postoperative inflammation, which may contribute to postoperative morbidity. Endogenous glucocorticoids (GCs) are an essential part of the stress response, but this response varies between individuals, which may in turn affect clinical outcome and specifically postoperative inflammation. Exon 1 of the NR3C1 gene, encoding the GC receptor (GR), contains an established region of differential regulation. DNA methylation patterns in this region have been found to differ between individuals. The present study investigated the methylation status and genotype in the cytosine­phosphate­guanine (CpG) island in exon 1 of NR3C1 in 24 patients [Median age 65.5 (range 42­81) years, 11 male, 13 female] who underwent major abdominal (12 pancreatic, 12 hepatic) surgery and explored its association with postoperative complications. DNA was extracted from peripheral blood leukocytes and underwent targeted bisulfite sequencing of the CpG island. Complications were graded according to the Clavien­Dindo classification and 14 out of 24 patients had postoperative complications. Multifactorial and partial least square analyses were used to analyse the data. A homogenous demethylated pattern was observed in all patients and no single CpG methylation was associated with postoperative complications. Four SNPs were significantly associated with higher Clavien­Dindo scores. Genetic variability in the chromosome 5:143,402,505­143,405,805 region of exon 1 of the GR gene NR3C1, but not DNA methylation, was associated with more severe postoperative complications in patients having major abdominal surgery. These results indicated that the patients' response to GCs may be of clinical importance for inflammatory conditions.

Genotype-dependent epigenetic regulation of DLGAP2 in alcohol use and dependence.

Alcohol misuse is a major public health problem originating from genetic and environmental risk factors. Alterations in the brain epigenome may orchestrate changes in gene expression that lead to alcohol misuse and dependence. Through epigenome-wide association analysis of DNA methylation from human brain tissues, we identified a differentially methylated region, DMR-DLGAP2, associated with alcohol dependence. Methylation within DMR-DLGAP2 was found to be genotype-dependent, allele-specific and associated with reward processing in brain. Methylation at the DMR-DLGAP2 regulated expression of DLGAP2 in vitro, and Dlgap2-deficient mice showed reduced alcohol consumption compared with wild-type controls. These results suggest that DLGAP2 may be an interface for genetic and epigenetic factors controlling alcohol use and dependence.

Hodgkin Lymphoma Monozygotic Triplets Reveal Divergences in DNA Methylation Signatures.

We studied DNA methylation profiles in four different cell populations from a unique constellation of monozygotic triplets in whom two had developed Hodgkin Lymphoma (HL). We detected shared differences in DNA methylation signatures when comparing the two HL-affected triplets with the non-affected triplet. The differences were observed in naïve B-cells and marginal zone-like B-cells. DNA methylation differences were also detected when comparing each of the HL-affected triplets against each other. Even though we cannot determine whether treatment and/or disease triggered the observed differences, we believe our data are important on behalf of forthcoming studies, and that it might provide important clues for a better understanding of HL pathogenesis.

Tobacco smoking induces changes in true DNA methylation, hydroxymethylation and gene expression in bronchoalveolar lavage cells.

BACKGROUND: While smoking is known to associate with development of multiple diseases, the underlying mechanisms are still poorly understood. Tobacco smoking can modify the chemical integrity of DNA leading to changes in transcriptional activity, partly through an altered epigenetic state. We aimed to investigate the impact of smoking on lung cells collected from bronchoalveolar lavage (BAL). METHODS: We profiled changes in DNA methylation (5mC) and its oxidised form hydroxymethylation (5hmC) using conventional bisulphite (BS) treatment and oxidative bisulphite treatment with Illumina Infinium MethylationEPIC BeadChip, and examined gene expression by RNA-seq in healthy smokers. FINDINGS: We identified 1667 total 5mC + 5hmC, 1756 5mC and 67 5hmC differentially methylated positions (DMPs) between smokers and non-smokers (FDR-adjusted P <.05, absolute Δß >0.15). Both 5mC DMPs and to a lesser extent 5mC + 5hmC were predominantly hypomethylated. In contrast, almost all 5hmC DMPs were hypermethylated, supporting the hypothesis that smoking-associated oxidative stress can lead to DNA demethylation, via the established sequential oxidation of which 5hmC is the first step. While we confirmed differential methylation of previously reported smoking-associated 5mC + 5hmC CpGs using former generations of BeadChips in alveolar macrophages, the large majority of identified DMPs, 5mC + 5hmC (1639/1667), 5mC (1738/1756), and 5hmC (67/67), have not been previously reported. Most of these novel smoking-associating sites are specific to the EPIC BeadChip and, interestingly, many of them are associated to FANTOM5 enhancers. Transcriptional changes affecting 633 transcripts were consistent with DNA methylation profiles and converged to alteration of genes involved in migration, signalling and inflammatory response of immune cells. INTERPRETATION: Collectively, these findings suggest that tobacco smoke exposure epigenetically modifies BAL cells, possibly involving a continuous active demethylation and subsequent increased activity of inflammatory processes in the lungs. FUND: The study was supported by the Swedish Research Council, the Swedish Heart-Lung Foundation, the Stockholm County Council (ALF), the King Gustav's and Queen Victoria's Freemasons' Foundation, Knut and Alice Wallenberg Foundation, Neuro Sweden, and the Swedish MS foundation.

Increased CD4+ T cell lineage commitment determined by CpG methylation correlates with better prognosis in urinary bladder cancer patients.

BACKGROUND: Urinary bladder cancer is a common malignancy worldwide. Environmental factors and chronic inflammation are correlated with the disease risk. Diagnosis is performed by transurethral resection of the bladder, and patients with muscle invasive disease preferably proceed to radical cystectomy, with or without neoadjuvant chemotherapy. The anti-tumour immune responses, known to be initiated in the tumour and draining lymph nodes, may play a major role in future treatment strategies. Thus, increasing the knowledge of tumour-associated immunological processes is important. Activated CD4+ T cells differentiate into four main separate lineages: Th1, Th2, Th17 and Treg, and they are recognized by their effector molecules IFN-γ, IL-13, IL-17A, and the transcription factor Foxp3, respectively. We have previously demonstrated signature CpG sites predictive for lineage commitment of these four major CD4+ T cell lineages. Here, we investigate the lineage commitment specifically in tumour, lymph nodes and blood and relate them to the disease stage and response to neoadjuvant chemotherapy. RESULTS: Blood, tumour and regional lymph nodes were obtained from patients at time of transurethral resection of the bladder and at radical cystectomy. Tumour-infiltrating CD4+ lymphocytes were significantly hypomethylated in all four investigated lineage loci compared to CD4+ lymphocytes in lymph nodes and blood (lymph nodes vs tumour-infiltrating lymphocytes: IFNG -4229 bp p < 0.0001, IL13 -11 bp p < 0.05, IL17A -122 bp p < 0.01 and FOXP3 -77 bp p > 0.05). Examination of individual lymph nodes displayed different methylation signatures, suggesting possible correlation with future survival. More advanced post-cystectomy tumour stages correlated significantly with increased methylation at the IFNG -4229 bp locus. Patients with complete response to neoadjuvant chemotherapy displayed significant hypomethylation in CD4+ T cells for all four investigated loci, most prominently in IFNG p < 0.0001. Neoadjuvant chemotherapy seemed to result in a relocation of Th1-committed CD4+ T cells from blood, presumably to the tumour, indicated by shifts in the methylation patterns, whereas no such shifts were seen for lineages corresponding to IL13, IL17A and FOXP3. CONCLUSION: Increased lineage commitment in CD4+ T cells, as determined by demethylation in predictive CpG sites, is associated with lower post-cystectomy tumour stage, complete response to neoadjuvant chemotherapy and overall better outcome, suggesting epigenetic profiling of CD4+ T cell lineages as a useful readout for clinical staging.

Author Correction: Smoking induces DNA methylation changes in Multiple Sclerosis patients with exposure-response relationship.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Evaluation of Post-Mortem Effects on Global Brain DNA Methylation and Hydroxymethylation.

The number of epigenetic studies on brain functions and diseases are dramatically increasing, but little is known about the impact of post-mortem intervals and post-sampling effects on DNA modifications such as 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Here, we examined post-mortem-induced changes in global brain 5mC and 5hmC levels at post-mortem intervals up to 540 min., and studied effects of tissue heat stabilization, using LUMA and ELISA. The global 5mC and 5hmC levels were generally higher in the cerebellum of adult rats than neonates. When measured by ELISA, the global 5mC content in adults, but not neonates, decreased with the post-mortem interval reaching a significantly lower level in cerebellum tissue at the post-mortem interval 540 min. (2.9 ± 0.7%; mean ± S.E.M.) compared to control (3.7 ± 0.6%). The global 5hmC levels increased with post-mortem interval reaching a significantly higher level at 540 min. (0.29 ± 0.06%) compared to control (0.19 ± 0.03%). This suggests that the post-mortem interval may confound 5mC and 5hmC analysis in human brain tissues as the post-mortem handling could vary substantially. The reactive oxygen species (ROS) level in cerebellum also increased over time, in particular in adults, and may be part of the mechanism that causes the observed post-mortem changes in 5mC and 5hmC. The global 5mC and 5hmC states were unaffected by heat stabilization, allowing analysis of tissues that are stabilized to preserve more labile analytes. Further studies in human samples are needed to confirm post-mortem effects on DNA methylation/hydroxymethylation and elucidate details of the underlying mechanisms.

Smoking induces DNA methylation changes in Multiple Sclerosis patients with exposure-response relationship.

Cigarette smoking is an established environmental risk factor for Multiple Sclerosis (MS), a chronic inflammatory and neurodegenerative disease, although a mechanistic basis remains largely unknown. We aimed at investigating how smoking affects blood DNA methylation in MS patients, by assaying genome-wide DNA methylation and comparing smokers, former smokers and never smokers in two Swedish cohorts, differing for known MS risk factors. Smoking affects DNA methylation genome-wide significantly, an exposure-response relationship exists and the time since smoking cessation affects methylation levels. The results also show that the changes were larger in the cohort bearing the major genetic risk factors for MS (female sex and HLA risk haplotypes). Furthermore, CpG sites mapping to genes with known genetic or functional role in the disease are differentially methylated by smoking. Modeling of the methylation levels for a CpG site in the AHRR gene indicates that MS modifies the effect of smoking on methylation changes, by significantly interacting with the effect of smoking load. Alongside, we report that the gene expression of AHRR increased in MS patients after smoking. Our results suggest that epigenetic modifications may reveal the link between a modifiable risk factor and the pathogenetic mechanisms.

High-specificity bioinformatics framework for epigenomic profiling of discordant twins reveals specific and shared markers for ACPA and ACPA-positive rheumatoid arthritis.

BACKGROUND: Twin studies are powerful models to elucidate epigenetic modifications resulting from gene-environment interactions. Yet, commonly a limited number of clinical twin samples are available, leading to an underpowered situation afflicted with false positives and hampered by low sensitivity. We investigated genome-wide DNA methylation data from two small sets of monozygotic twins representing different phases during the progression of rheumatoid arthritis (RA) to find novel genes for further research. METHODS: We implemented a robust statistical methodology aimed at investigating a small number of samples to identify differential methylation utilizing the comprehensive CHARM platform with whole blood cell DNA from two sets of twin pairs discordant either for ACPA (antibodies to citrullinated protein antigens)-positive RA versus ACPA-negative healthy or for ACPA-positive healthy (a pre-RA stage) versus ACPA-negative healthy. To deconvolute cell type-dependent differential methylation, we assayed the methylation patterns of sorted cells and used computational algorithms to resolve the relative contributions of different cell types and used them as covariates. RESULTS: To identify methylation biomarkers, five healthy twin pairs discordant for ACPAs were profiled, revealing a single differentially methylated region (DMR). Seven twin pairs discordant for ACPA-positive RA revealed six significant DMRs. After deconvolution of cell type proportions, profiling of the healthy ACPA discordant twin-set revealed 17 genome-wide significant DMRs. When methylation profiles of ACPA-positive RA twin pairs were adjusted for cell type, the analysis disclosed one significant DMR, associated with the EXOSC1 gene. Additionally, the results from our methodology suggest a temporal connection of the protocadherine beta-14 gene to ACPA-positivity with clinical RA. CONCLUSIONS: Our biostatistical methodology, optimized for a low-sample twin design, revealed non-genetically linked genes associated with two distinct phases of RA. Functional evidence is still lacking but the results reinforce further study of epigenetic modifications influencing the progression of RA. Our study design and methodology may prove generally useful in twin studies.

Ovarian Cancer Risk Factors by Histologic Subtype: An Analysis From the Ovarian Cancer Cohort Consortium.

PURPOSE: An understanding of the etiologic heterogeneity of ovarian cancer is important for improving prevention, early detection, and therapeutic approaches. We evaluated 14 hormonal, reproductive, and lifestyle factors by histologic subtype in the Ovarian Cancer Cohort Consortium (OC3). PATIENTS AND METHODS: Among 1.3 million women from 21 studies, 5,584 invasive epithelial ovarian cancers were identified (3,378 serous, 606 endometrioid, 331 mucinous, 269 clear cell, 1,000 other). By using competing-risks Cox proportional hazards regression stratified by study and birth year and adjusted for age, parity, and oral contraceptive use, we assessed associations for all invasive cancers by histology. Heterogeneity was evaluated by likelihood ratio test. RESULTS: Most risk factors exhibited significant heterogeneity by histology. Higher parity was most strongly associated with endometrioid (relative risk [RR] per birth, 0.78; 95% CI, 0.74 to 0.83) and clear cell (RR, 0.68; 95% CI, 0.61 to 0.76) carcinomas (P value for heterogeneity [P-het] < .001). Similarly, age at menopause, endometriosis, and tubal ligation were only associated with endometrioid and clear cell tumors (P-het ≤ .01). Family history of breast cancer (P-het = .008) had modest heterogeneity. Smoking was associated with an increased risk of mucinous (RR per 20 pack-years, 1.26; 95% CI, 1.08 to 1.46) but a decreased risk of clear cell (RR, 0.72; 95% CI, 0.55 to 0.94) tumors (P-het = .004). Unsupervised clustering by risk factors separated endometrioid, clear cell, and low-grade serous carcinomas from high-grade serous and mucinous carcinomas. CONCLUSION: The heterogeneous associations of risk factors with ovarian cancer subtypes emphasize the importance of conducting etiologic studies by ovarian cancer subtypes. Most established risk factors were more strongly associated with nonserous carcinomas, which demonstrate challenges for risk prediction of serous cancers, the most fatal subtype.

Global Analysis of DNA 5-Methylcytosine Using the Luminometric Methylation Assay, LUMA.

The study of epigenetic alterations of the genome is becoming increasingly important in order to understand how environment and genetic background interact to build and regulate the functional genome. There are several types of epigenetic modifications to both DNA and histone proteins in eukaryotic cells; chiefly studied among these are changes to cytosine, where methylation of the 5-carbon position is the most prominent. Although this has many consequences for gene regulation and cell differentiation, other modifications have recently emerged as biologically relevant. Since global DNA methylation states may be used as a general measure of the methylome, cost-effective, rapid, and specific analytical tools are wanted.This protocol described here focuses on the Luminometric Methylation Assay (LUMA), a method which analyzes global DNA 5-methylcytosine (5mC) through the use of restriction enzymes and detection with Pyrosequencing(®). Up to 96 samples can be simultaneously analyzed. In contrast to the majority of other methods focused on 5mC analysis, with appropriate enzymes, LUMA does not appear to detect 5-hydroxymethylcytosine (5hmC) and is therefore more specific than most 5mC techniques.

Increased DNA methylation levels of the insulin-like growth factor binding protein 1 gene are associated with type 2 diabetes in Swedish men.

BACKGROUND: Prospective studies have shown that low levels of circulating insulin-like growth factor binding protein-1 (IGFBP-1) are associated with the risk of type 2 diabetes. In the present study, we investigated DNA methylation in the IGFBP1 gene to evaluate its changes in relation to serum IGFBP-1 levels in type 2 diabetes. RESULTS: A total of 406 Swedish men, including age-matched normal glucose tolerance subjects and type 2 diabetes patients either newly diagnosed or undergoing treatment, were selected from the Stockholm Diabetes Prevention Program. IGFBP1 methylation levels in genomic DNA extracted from peripheral blood were analysed by bisulfite pyrosequencing. Serum IGFBP-1 levels were measured by radio-immunoassay. We found that IGFBP1 DNA methylation levels were higher in both newly diagnosed and treated type 2 diabetes patients with a mean diabetes duration of 3 years compared with subjects with normal glucose tolerance (19.8% and 20.2% vs. 16.9%, P < 0.001 for both). Serum levels of IGFBP-1 in newly diagnosed and in treated type 2 diabetes patients were lower compared with healthy individuals (18 µg/l both vs. 24 µg/l, P = 0.011, P < 0.001). IGFBP1 methylation levels but not serum IGFBP-1 levels in type 2 diabetes patients were independent of body mass index. Newly diagnosed patients with a family history of diabetes (FHD) had higher IGFBP1 methylation levels than those without FHD (20.3% vs. 18.6%, P = 0.017). CONCLUSIONS: This study provides the first evidence that changes in DNA methylation of the IGFBP1 gene are associated with type 2 diabetes in Swedish men and suggests that increased IGFBP1 DNA methylation and decreased IGFBP-1 serum levels are features of type 2 diabetes with a short duration.

Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities.

Monoamine oxidase A (MAOA) harbours a polymorphic upstream variable-number tandem repeat (u-VNTR). The MAOA-L allele of the u-VNTR leads to decreased gene expression levels in vitro and has been found to increase the risk of conduct disorder in males with childhood adversities. Early-life adversities have been associated with hypermethylation of the glucocorticoid receptor (NR3C1). In this study, we first performed a genetic association analysis of the MAOA u-VNTR using individuals with depression (n = 392) and controls (n = 1276). Next, DNA methylation analyses of MAOA and NR3C1 were performed using saliva samples of depressed and control subgroups. Adult MAOA-L females with childhood adversities were found to have a higher risk of developing depression (p = 0.006) and overall MAOA methylation levels were decreased in depressed females compared to controls (mean depressed, 42% vs. mean controls, 44%; p = 0.04). One specific childhood adversity [early parental death (EPD)] was associated with hypermethylation of NR3C1 close to an NGFI-A binding site (mean EPD, 19% vs. mean non-EPD, 14%; p = 0.005). Regression analysis indicated that this association may be mediated by the MAOA-L allele (adjusted R² = 0.24, ANOVA: F = 23.48, p < 0.001). Conclusively: (1) depression in females may result from a gene × childhood-adversity interaction and/or a dysregulated epigenetic programming of MAOA; (2) childhood-adversity subtypes may differentially impact DNA methylation at NR3C1; (3) baseline MAOA-genotypic variations may affect the extent of NR3C1 methylation.

Nurture your scientific curiosity early in your research career.

Uncertainty makes scientific research challenging and at the same time exciting. Whereas curiosity and passion for uncovering the unknown drive future generations of researchers, the landscape of science has changed. We investigated whether the requirements for having a successful research career are changing, and whether junior researchers are aware of these requirements. Structured discussion with peers and more experienced researchers can point the way forward to an excellent career.

Influence of serotonin transporter promoter variation on the effects of separation from parent/partner on depression.

BACKGROUND: Loss of parent during childhood or loss of partner has been associated with adulthood depression. The serotonin transporter polymorphism (5-HTTLPR) has been reported to moderate stress sensitivity reflected for example in the relationship between childhood maltreatment and depression. Therefore, the effect of 5-HTT promoter variation on the relationship between the loss of parent or partner and depression was examined. METHOD: 411 depressive cases and 1347 control subjects from a large well-characterized longitudinal population-based sample of adult Swedes with data on life history and life situation, including psychiatric diagnostic instruments, were studied. Their DNA was genotyped for the mini-haplotype 5-HTTLPR-rs25531. RESULTS: Individuals with low 5-HTT activity variants had an increased risk of depression given loss of partner last year compared to those with high activity variants. Conversely, 5-HTT activity variation appeared not to strongly influence the risk of depression given loss of parent during childhood. LIMITATION: Small sample size for those with losses of both parent and partner. Limited power to detect small interaction effects. CONCLUSION: The increased risk of depression given last year loss of partner appeared to be influenced by genetic variation regulating 5-HTT activity. This adds to previous findings of 5-HTT x stressful life events interactions on depression and is in agreement with stronger GxE effects when using objective environmental measures.

The functional Val158Met polymorphism in catechol-O-methyltransferase (COMT) is associated with depression and motivation in men from a Swedish population-based study.

BACKGROUND: Environmental risk factors together with genetic vulnerability create a complex background to develop depression. METHODS: We investigated the associations between COMT Val(158)Met and depression in a Swedish population-based sample of 405 depressed individuals (major depression diagnosis, dysthymia or mixed anxiety depression defined according to DSM-IV) and 2,151 healthy controls. We also analyzed interaction between this genetic variation and some environmental risk factors for depression and the link between this polymorphism and the low motivational level and negative mood state found in depressed individuals. RESULTS: Depressed individuals displayed a higher frequency of the Met/Met and Met/Val genotypes compared to controls (OR=1.49, CI(95%)=1.11-2.00, P=0.009). The association was found among men only (OR=2.26, CI(95%)=1.26-4.05, p=0.008). Regression analysis including some potential risk factors for depression, did further indicate that Met/Met and Met/Val were associated with depression in men (P=0.005). There was also an interaction between genotype and family childhood problems (RERI=0.876, CI(95%)=0.090-1.662 and AP=0.426, CI(95%)=0.030-0.821). Further, depressed men homozygous for the Val-allele, had a higher motivational level than depressed men with a Met-variant (P=0.02). LIMITATIONS: The sample size of depressed individuals per group when stratifying cases according to gender and genotypes is considered a limitation. CONCLUSIONS: The Met-variants of COMT Val(158)Met are risk variants for depression and low motivational level in depressed Swedish men, but not women. Individuals with this risk variant in combination with a problematic childhood, have an even higher risk to develop depression.

CRY2 is associated with rapid cycling in bipolar disorder patients.

BACKGROUND: Bipolar disorder patients often display abnormalities in circadian rhythm, and they are sensitive to irregular diurnal rhythms. CRY2 participates in the core clock that generates circadian rhythms. CRY2 mRNA expression in blood mononuclear cells was recently shown to display a marked diurnal variation and to respond to total sleep deprivation in healthy human volunteers. It was also shown that bipolar patients in a depressive state had lower CRY2 mRNA levels, nonresponsive to total sleep deprivation, compared to healthy controls, and that CRY2 gene variation was associated with winter depression in both Swedish and Finnish cohorts. PRINCIPAL FINDINGS: Four CRY2 SNPs spanning from intron 2 to downstream 3'UTR were analyzed for association to bipolar disorder type 1 (n = 497), bipolar disorder type 2 (n = 60) and bipolar disorder with the feature rapid cycling (n = 155) versus blood donors (n = 1044) in Sweden. Also, the rapid cycling cases were compared with bipolar disorder cases without rapid cycling (n = 422). The haplotype GGAC was underrepresented among rapid cycling cases versus controls and versus bipolar disorder cases without rapid cycling (OR = 0.7, P = 0.006-0.02), whereas overrepresentation among rapid cycling cases was seen for AAAC (OR = 1.3-1.4, P = 0.03-0.04) and AGGA (OR = 1.5, P = 0.05). The risk and protective CRY2 haplotypes and their effect sizes were similar to those recently suggested to be associated with winter depression in Swedes. CONCLUSIONS: We propose that the circadian gene CRY2 is associated with rapid cycling in bipolar disorder. This is the first time a clock gene is implicated in rapid cycling, and one of few findings showing a molecular discrimination between rapid cycling and other forms of bipolar disorder.

CRY2 is associated with depression.

BACKGROUND: Abnormalities in the circadian clockwork often characterize patients with major depressive and bipolar disorders. Circadian clock genes are targets of interest in these patients. CRY2 is a circadian gene that participates in regulation of the evening oscillator. This is of interest in mood disorders where a lack of switch from evening to morning oscillators has been postulated. PRINCIPAL FINDINGS: We observed a marked diurnal variation in human CRY2 mRNA levels from peripheral blood mononuclear cells and a significant up-regulation (P = 0.020) following one-night total sleep deprivation, a known antidepressant. In depressed bipolar patients, levels of CRY2 mRNA were decreased (P = 0.029) and a complete lack of increase was observed following sleep deprivation. To investigate a possible genetic contribution, we undertook SNP genotyping of the CRY2 gene in two independent population-based samples from Sweden (118 cases and 1011 controls) and Finland (86 cases and 1096 controls). The CRY2 gene was significantly associated with winter depression in both samples (haplotype analysis in Swedish and Finnish samples: OR = 1.8, P = 0.0059 and OR = 1.8, P = 0.00044, respectively). CONCLUSIONS: We propose that a CRY2 locus is associated with vulnerability for depression, and that mechanisms of action involve dysregulation of CRY2 expression.

Variations in FKBP5 and BDNF genes are suggestively associated with depression in a Swedish population-based cohort.

BACKGROUND: Genetic variations in FKBP5, BDNF, P2RX7 and CACNA1 are current candidates for involvement in depression. METHODS: The single nucleotide polymorphisms FKBP5:rs1360780, BDNF:rs6265 (Val66Met), P2RX7:2230912 (Gln460Arg) and CACNA1C:rs1006737 were genotyped in DNA from 457 depression cases (major depression, dysthymia, and mixed anxiety depression) and 2286 healthy controls with no symptom of psychopathology. Cases and controls were derived from a large well-characterized longitudinal population-based sample of adult Swedes with data on life situation and life history. Association to depression was analyzed with and without consideration to problems during childhood and negative life events last year. RESULTS: FKBP5:rs1360780 allele T and genotype TT were overrepresented in depression for men. Childhood problems and negative life events (two or more) conferred a risk for depression (OR=2.8, 95% CI: 2.2-3.5 and OR=2.9, 95% CI: 2.4-3.7, respectively). The BDNF:rs6265 Met-allele was overrepresented in depression for women with problems during their childhood. No indication for association to depression was found for P2RX7:2230912 and CACNA1C:rs1006737 without or with consideration of childhood problems or negative life events. LIMITATIONS: The sample size did not allow exclusion of true association to depression at low odds ratios. There was possibly some recall bias of childhood problems. CONCLUSIONS: These data support previous reports on FKBP5:rs1360780 and show a gender difference. Likewise, they support previous reports on BDNF:rs6265 and show involvement of environmental stress. P2RX7:2230912 and CACNA1C:rs1006737 did not have a large or moderate-size effect on depression risk. Further studies are required to estimate the significance of these findings.

Examining the public refusal to consent to DNA biobanking: empirical data from a Swedish population-based study.

OBJECTIVES: To investigate empirically the motivations for not consenting to DNA biobanking in a Swedish population-based study and to discuss the implications. DESIGN: Structured questionnaires and semistructured interviews. SETTING: A longitudinal epidemiological project (PART) ongoing since 1998 in Stockholm, Sweden. The DNA-collection wave took place during 2006-7. PARTICIPANTS: 903 individuals completed the questionnaire (participation rate 36%) and 23 were interviewed. All individuals had participated in both non-genetic waves of the project, but refused to contribute saliva samples during the DNA-collection wave. MAIN OUTCOME MEASURES: Motivations behind refusing to consent to DNA biobanking, with subsequent focus on participants' explanations regarding this unwillingness. RESULTS: Public refusal to consent to DNA biobanking, as revealed by the questionnaire, was mainly explained by a lack of personal relevance of DNA contribution and feelings of discomfort related to the DNA being used for purposes other than the respective study. Interviews of individuals representing the second motivation, revealed a significant mistrust of DNA biobank studies. The underlying beliefs and attitudes were associated with concerns about integrity, privacy, suspiciousness and insecurity. However, most interviewees were supportive of genetic research per se and interpreted their mistrust in the light of distressing environmental influences. CONCLUSION: The results suggest a need for guidelines on benefit sharing, as well as trustworthy and stable measures to maintain privacy, as a means for increasing personal relevance and trust among potential participants in genetic research. Measures taken from biobanks seem insufficient in maintaining and increasing trust, suggesting that broader societal measures should be taken.