BACKGROUND:A growing body of evidence links microRNAs (miRNAs) to major depressive disorder (MDD). However, the causal nature of these associations remains unclear. OBJECTIVES:This study aimed to investigate the potential causal association between miRNAs and MDD by combining Mendelian Randomization (MR) analyses and experimental validation. METHODS:Single-nucleotide polymorphisms (SNPs) significantly associated with the expression levels of miRNAs identified in the Framingham Heart Study (FHS) were used as instrumental variables serving as a proxy for miRNA exposure. The outcome was derived from the genome-wide association study (GWAS) of MDD (cases = 170,756, controls = 329,443). Two-sample MR was conducted to assess the association of miRNAs with MDD. The miRNAs identified from MR analyses were further validated in blood samples from individuals in the Women's Health in Lund Area (WHILA) cohort using qPCR. RESULTS:MR analysis identified six miRNAs significantly associated with MDD risk, including miR-133a-3p [Odds Ratio (OR) = 1.03, 95% Confidence interval (CI):1.00-1.05], miR-130a-3p (OR = 1.06, 95% CI:1.03-1.09), miR-138-5p (OR = 1.06, 95% CI:1.01-1.11), miR-629-5p (OR = 0.96, 95% CI:0.93-0.99), miR-132-3p (OR = 0.97, 95% CI:0.94-1.00) and miR-635-3p (OR = 0.97, 95% CI:0.95-0.99). Among them, miR-130a-3p (OR = 2.06, 95% CI:1.08-4.28, P = 0.04) and miR-132-3p (OR = 0.51, 95% CI:0.29-0.88, P = 0.02) were further confirmed to be associated with MDD by experimental validation. CONCLUSIONS:Combining genetic and experimental approaches, this study provides evidence supporting a potential causal role for specific circulating miRNAs in MDD. While the MR findings were limited by single-SNP instruments, precluding formal pleiotropy assessment, the experimental validation of miR-130a-3p and miR-132-3p strengthens the evidence. Further research with multi-SNP instruments and larger cohorts are needed to confirm causality and explore clinical relevance.

BackgroundAlterations in ribosomal DNA copy number (rDNA-CN) and global DNA methylation have been associated with genomic instability and various diseases. However, their relevance in myocardial infarction (MI) has not been fully investigated.MethodsWe measured rDNA-CN and global DNA methylation in blood samples from MI patients (n = 100) and healthy controls (n = 109) using Droplet Digital PCR (ddPCR) and ELISA, respectively. Logistic regression was used to assess associations with MI, before and after adjustment for age and sex. Correlations of rDNA CN and global DNA methylation with age were also evaluated. Discriminatory performance was assessed using receiver operating characteristic (ROC) curve analysis.ResultsrDNA-CN was associated with MI in the unadjusted analysis (OR=0.991, p < 0.001), but the effect was no longer significant after adjusting for age and sex (OR=0.992, p = 0.06). In contrast, global DNA methylation remained significantly associated with MI after adjustment (OR=1.61, p < 0.001). Global DNA methylation also demonstrated strong discriminative ability for MI (AUC = 0.97).ConclusionsGlobal DNA methylation was independently associated with MI after the adjustments, whereas rDNA-CN was not. These findings suggest that global DNA methylation may represent a potential biomarker; however, further validation in larger, well-characterized populations is warranted.

A Palaeolithic diet is an efficacious dietary approach for glycaemic control in type 2 diabetes. Causal mechanisms are body weight loss and glucometabolic effects from differences in included food groups, macronutrient composition, fibre content, and glycaemic load. The aim was to test the hypothesis that characteristic food group differences between a Palaeolithic and a diabetes diet would cause an effect on glycaemic control when weight was kept stable and diets were matched for macronutrient composition, fibre content and glycaemic load. Adult participants with type 2 diabetes and increased waist circumference were instructed to follow two diets, with or without the food groups cereal grain, dairy products, and legumes, during two periods of 4 weeks separated by a 6-week washout period in a random-order crossover design. The Palaeolithic diet included fruit, vegetables, tubers, fish, shellfish, lean meat, nuts, eggs and olive oil, and excluded cereal grains, dairy products and legumes. The diabetes diet included fruit, vegetables, fish, shellfish, lean meat, nuts, eggs, olive oil, and substantial amounts of whole grains, low-fat dairy products and legumes. Dietary energy content was adjusted throughout the study to maintain stable body weight. There were no differences between diets on HbA1c or fructosamine among the 14 participants. Body weight was kept stable, and the two diets were successfully matched for macronutrient composition and glycaemic load but not for fibre content. Characteristic food group differences and the accompanying differences in fibre content between a Palaeolithic and a diabetes diet do not cause an effect on glycaemic control.

INTRODUCTION:Breast cancer, a leading female cancer worldwide, can be influenced by mitochondrial dysfunction. Dysregulation of mitochondria by the nuclear genome may cause breast cancer initiation and progression. However, the comprehensive investigation of mitochondrial-related genes as prognostic marker for the overall survival of early-stage breast cancer patients is still limited. METHODS:To address this, we employed machine learning methods to identify a concise set of mitochondrial-related genes with high accuracy and reliability in predicting survival outcomes. Bulk transcriptome collected from Sweden Cancerome Analysis Network - Breast (SCANB) was divided into training and testing datasets and the Cancer Genome Atlas Breast Invasive Carcinoma (TCGA-BRCA) was included as the external validation cohort. The 1136 known mitochondrial-related genes were analysed using univariate Cox regression, bootstrap and Lasso Cox regression in the SCANB training cohort for model construction. RESULTS:We identified a 14-gene mitochondrial signature that independently predicts the survival outcome of breast cancer (adjusted hazard ratio [HR]: 2.08, 95% confidence interval [CI]: 1.20-3.62) in the SCANB dataset. A highly predictive nomogram was further constructed by integrating the mitochondrial signature with clinical variables, enabling robust prediction of overall survival at 1-, 3- and 5-year. This model demonstrated strong predictive capability in both the training cohort (the area under the receiver operating characteristic [ROC] curve [AUC]: 0.84, 0.79, 0.78) and validation cohort (AUC: 0.92, 0.83, 0.78). CONCLUSION:In this study, we suggested a novel mitochondrial signature model by comprehensively analysing mitochondrial-related genes, which have the potential to accurately predict the clinical prognosis at the early stages of breast cancer.

Venous thromboembolism (VTE) involves blood clot formation in veins, resulting in serious health issues. Fibrinogen, a crucial clotting protein, consists of three polypeptides encoded by the fibrinogen genes: alpha (FGA), beta (FGB) and gamma (FGG). We genotyped most common missense variants in the fibrinogen genes in relation to VTE, recurrence and family history in Malmö Thrombophilia Study, including 1465 VTE patients followed for ~10 years and 429 healthy donors. FGG (rs6063) was significantly associated with increased odds of primary VTE (odds ratio [OR] = 8.2; 95% confidence interval [CI] = 1.05-63.6) after adjusting for age and sex. For recurrent VTE, Cox-regression analysis indicated a higher risk associated with FGA (rs6050) (hazard ratio [HR] = 1.8; 95% CI = 1.1-2.8), with even greater risk for unprovoked recurrent VTE (HR = 2.3; 95% CI = 1.3-4.2), surpassing the well-known factor V Leiden (FVL) (HR = 1.9; 95% CI = 1.2-3.0). Combining risk alleles from FVL and FGA (rs6050) significantly raised the risk for unprovoked recurrent VTE: ≥3 risk alleles (HR = 4.6; 95% CI = 1.9-11.3), two risk alleles (HR = 2.6; 95% CI = 1.4-4.8) and one risk allele (HR = 1.5; 95% CI = 0.8-2.7) compared to 0 risk allele. Prevalence of FGA (rs6050) risk allele was significantly higher in cases with a family history of VTE. We propose FGA (rs6050) as a novel predictor for unprovoked recurrent VTE and it may contribute to the familial occurrence of VTE.

BACKGROUND:Brain-derived neurotrophic factor (BDNF) plays a critical role in neuronal development and neural connectivity, and has been implicated in the pathophysiology of Major Depressive Disorder (MDD). However, its predictive value for MDD onset remains unclear. This study examined whether baseline BDNF levels are associated with incident MDD in middle-aged women. MATERIAL AND METHODS:In this nested case-control study, 104 individuals (mean age = 56.0) without MDD at baseline were selected from a population-based follow-up cohort. Over five years, 52 developed MDD (cases) and 52 remained MDD-free (controls). Baseline plasma BDNF levels were measured using a Luminex assay. Associations between BDNF levels and MDD risk were assessed using multivariable logistic regression adjusted for age and BMI. RESULTS:MDD cases exhibited significantly higher baseline plasma BDNF levels compared to controls (median: 2683 vs 1844 pg/ml, p = 0.01). Elevated BDNF was associated with increased MDD risk in the univariate analysis (OR = 1.78, 95 % CI = 1.20-2.78, p = 0.006) and remained significant after adjusting for age, BMI, lifestyle, and socioeconomic factors (fully adjusted OR = 1.84, 95 % CI = 1.20-3.02, p = 0.009). BDNF elevation was most pronounced in MDD cases diagnosed 2-5 years after baseline. CONCLUSION:Our findings challenge the view that BDNF is solely protective against MDD, as our study links higher plasma BDNF levels to increased MDD risk. These results suggest that higher BDNF levels may reflect underlying mechanisms contributing to MDD onset, highlighting the need to further investigate BDNF's role as a potential risk biomarker.

Background SLE is associated with significant morbidity, especially in the case of renal involvement. Mitochondrial dysfunction plays a significant role in SLE and may be assessed by measuring mitochondrial DNA (mtDNA) and cytokines reflecting mitochondrial stress (mitokines). Circulating mtDNA is a promising biomarker in SLE and appears to be reduced in severe SLE. However, measuring circulating mtDNA is challenging and reported methods are heterogenous. Our study aimed at evaluating whole blood mtDNA to nuclear DNA (nucDNA) ratio using droplet-digital PCR and circulating mitokines, growth differentiation factor 15 (GDF-15) and fibroblast growth factor 21 in SLE with and without renal involvement.Methods Cross-sectional study involving 195 patients with SLE and age-matched healthy volunteers (HV) as control. Biomarkers were compared in patients with and without renal involvement (defined by estimated glomerular filtration rate <60 mL/min or proteinuria >0.5 g/day) and in those with active and inactive SLE.Results Compared with HV, patients with SLE displayed lower mtDNA/nucDNA ratios, especially in the case of renal involvement. Accordingly, mitokines were increased in patients with SLE with renal involvement. We found no correlation between mtDNA/nucDNA ratio and global disease activity. Mitokine levels, on the other hand, correlated with disease activity, in particular GDF-15 even after adjusting for renal involvement.Conclusion Our findings suggest that lower whole blood mtDNA/nucDNA ratio, a surrogate marker for mitochondrial dysfunction, reflects renal damage, while GDF-15 may also reflect disease activity in SLE. Further studies are needed to assess the clinical value of these markers as predictors for active lupus nephritis.

Background:Mitochondrial DNA copy number (mtDNA-CN) is associated with aging. A relationship between mtDNA-CN and degenerative disorders, e.g. osteoarthritis (OA) and osteoporosis (OP), has been suggested. We aimed to investigate the relationship of mtDNA-CN and incident OA and OP. Materials and methods:MtDNA-CN was studied in relationship to incident OA and OP in a population-based cohort study of 6916 middle-aged women (52-63 years). Totally 2521 women with sufficient quality of mtDNA were analyzed. After exclusions, 1978 women remained in the study population. Four different endpoints obtained from the National Patient register were studied: 1) OA, 2) OP 3) OA surgery, and 4) OP fracture. In the multivariate model adjustments were made for potential OA and OP risk factors. Results:Women with low mtDNA-CN were older and had more activity at work. 125 women (6.32%) were affected by incident OP and 254 women (12.84%) had an OP fracture. Incident OA affected 451 women (22.80%) and 175 women (8.85%) had OA surgery. There were no associations between mtDNA-CN and incident risk of OA (Hazard ratio ​= ​1.00, 95% confidence interval 0.83-1.20), OA surgery (0.79, 0.58-1.07), OP (0.89, 0.62-1.27), or OP fracture (1.00, 0.78-1.29). However, incident OP was significantly associated with T-score (bone density), smoking, diabetes mellitus, and chronic obstructive bronchitis (COPD). OA was associated with body mass index and COPD. Conclusions:The present study suggests that mtDNA-CN, reflecting mitochondrial dysfunction, is not a major predictor for incident OA or OP. However, due to the limited study size minor associations cannot be excluded.

Abstract Background Beneficial effects from practising a Paleolithic diet as compared to a diabetes diet on weight, waist circumference, satiety, leptin, HbA1c and glucose control in randomised controlled trial participants with type 2 diabetes could be due to lower leptin resistance. Support for this hypothesis comes from an in vitro experiment that showed that digested wheat gluten, which is excluded from a Paleolithic diet, inhibits leptin from binding to its receptor, thus indicating a possible dietary cause of leptin resistance. However, the clinical relevance of the latter finding is unclear since removal of enzyme activity from the gluten digest by heat treatment also abolished leptin binding inhibition. Assessment of leptin binding inhibition in vivo is possible by comparison of total leptin levels with those of ‘biologically active’ leptin bound to its receptor (bioLep). Objectives To assess the effects of a Paleolithic diet compared to a diabetes diet on leptin binding inhibition and to replicate our in vitro study. Methods BioLep and total leptin levels were measured in secondary analysis of fasting plasma samples from our open label random order three plus three-month long cross-over trial performed in 2005–2007, that compared a Paleolithic diet with a diabetes diet in participants with type 2 diabetes without insulin treatment (per protocol). BioLep was also measured in vitro for known recombinant leptin concentrations incubated with a series of concentrations of 10 kDa spin-filtered digested wheat gluten, with or without prior heat treatment, at 100ºC for 30 min and centrifugation. Results There was no difference between diets when comparing differences between bioLep and total leptin levels and their ratio in the 13 participants, three women and 10 men, aged 52–74 years with a mean BMI of 30 kg/m2 and a mean diabetes duration of eight years. We found no carry-over or period effect for bioLep and total leptin. In vitro, wheat gluten digest inhibited leptin binding in a dose-dependent manner but not after heat treatment. Conclusions We found no leptin binding inhibition after the Paleolithic or diabetes diet, possibly due to its abolishment from cooking-related heat treatment of wheat gluten. Trial registration Registered on 14/02/2007 at ClinicalTrials.gov Identifier: NCT00435240.

AIMS:The aim of this study is to investigate how genetic variations in genes related to oxidative stress, intake of antioxidant vitamins, and any potential interactions between these factors affect the incidence of intact abdominal aortic aneurysm (AAA) and its rupture (rAAA), accounting for sex differences where possible. METHODS AND RESULTS:The present retrospective cohort study (n = 25 252) uses baseline single-nucleotide polymorphisms (SNPs) and total antioxidant vitamin intake data from the large population-based, Malmö Diet and Cancer Study. Cumulative incidence of intact AAA was 1.6% and of rAAA 0.3% after a median follow-up of 24.3 years. A variant in NOX3 (rs3749930) was associated with higher rAAA risk in males [adjusted hazard ratio (aHR): 2.49; 95% confidence interval (CI): 1.36-4.35] and the overall population (aHR: 1.88; 95% CI: 1.05-3.37). Higher intakes of antioxidant vitamins, riboflavin, and folate were associated with 20% and 19% reduced intact AAA incidence, respectively. Interestingly, the inverse associations between riboflavin and vitamin D intake with intact AAA incidence were stronger in the individuals carrying the NOX3 variant as compared with the wild-type recessive genotype, i.e. by 60% and 66%, respectively (P for interaction < 0.05). Higher riboflavin intake was associated with a 33% male-specific intact AAA risk reduction, while higher intake of vitamin B12 intake was associated with 55% female-specific intact AAA risk increase; both these associations were significantly modified by sex (P for interaction < 0.05). CONCLUSIONS:Our findings highlight the role of oxidative stress genetic variations and antioxidant vitamin intake in AAA. Although a low AAA/rAAA sample size limited some analyses, especially in females, our findings highlight the need for future randomized controlled trials and mechanistic studies, to explore the potential benefits of antioxidant vitamins while accounting for genetic and sex differences.

Background There is increasing evidence implicating hemoglobin/heme and their scavengers in oxidative stress-mediated pathologies, but information is limited in abdominal aortic aneurysm (AAA). Methods and results In this case-control study, we assessed heme/heme-related markers in 142 men with AAA and 279 men with a normal aortic diameter consecutively recruited from an ultrasound screening program in Sweden. Enzyme-linked immunosorbent assays (ELISAs) were used to measure heme oxygenase-1 (HO-1) and hemopexin (Hpx) plasma levels, colorimetric assays for cell-free heme and whole blood hemoglobin (Hb) levels, and droplet digital PCR (ddPCR) and real-time PCR to determine haptoglobin (Hp) (pheno)type and genotype, respectively. Hpx and heme plasma levels at baseline were elevated, while HO-1 levels were lower in men with AAA (p < 0.001) and were significantly associated with AAA prevalence independently of potential confounders. A combination of heme and HO-1 showed the best diagnostic potential based on the area under the curve (AUC): 0.76, sensitivity: 80%, specificity: 48%. Additionally, when previously described inflammatory biomarker interleukin-6 (IL-6), was added to our model it significantly improved the diagnostic value (AUC: 0.87, sensitivity: 80%, specificity: 79%) compared to IL-6 alone (AUC: 0.73, sensitivity: 80%, specificity: 49%). Finally, Hb (positively) and Hpx (negatively) levels at baseline were associated with AAA growth rate (mm/year), and their combination showed the best prognostic value for discriminating fast and slow-growing AAA (AUC: 0.76, sensitivity: 80%, specificity: 62%). Conclusions This study reports the distinct disruption of heme and related markers in both the development and progression of AAA, underscoring their potential in aiding risk stratification and therapeutic strategies.

Mitochondrial dysfunction is a recognized factor in the pathogenesis of deep vein thrombosis (DVT). The role of 7S RNA, a long noncoding RNA that plays an important role in mitochondrial function, in DVT remains unclear. In this study, we aimed to investigate the potential use of 7S RNA as a biomarker in DVT. Plasma samples were obtained from 237 patients (aged 16-95 years) with suspected DVT recruited in a prospective multicenter management study (SCORE) where 53 patients were objectively confirmed with a diagnosis of DVT and the rest were diagnosed as non -DV T. 7S RNA was measured using quantitative real-time polymerase chain reaction in plasma samples. The plasma expression of 7S RNA was significantly lower in DVT compared with non -DV T (0.50 vs. 0.95, p = 0.043). With the linear regression analysis, we showed that the association between the plasma expression of 7S RNA and DVT (beta = -0.72, p = 0.007) was independent of potential confounders. Receiver -operating characteristic curve analysis showed the area under the curve values of 0.60 for 7S RNA. The findings of the present study showed a notable association between 7S RNA and DVT. However, further investigations are needed to fully elucidate the exact role of 7S RNA in the pathophysiology of DVT and its diagnostic value.

OBJECTIVE:This longitudinal study examines a possible causal effect between type 2 diabetes and ischemic heart disease (IHD) by using measurements on four occasions from the Swedish Statistics on Income and Living Conditions (SILC) together with nationwide healthcare registers. METHODS:This was a longitudinal study based on a random sample of men and women (n = 2014) from the Swedish population with four measurements in the SILC every eight years. Baseline was 1980/81 and the participants were followed for up to 37 years. The mean age and age range at baseline were 36.5 and 20-59 years, respectively. The study used Marginal Structural Modeling (MSM-Cox) to account for time-varying exposures by implementing inverse probability weighting (IPTW). MSM-Cox with IPTW was compared with Cox proportional hazard modelling. RESULTS:The hazard ratio (HR) for IHD (369 cases) with 95% confidence interval (CI) in participants with type 2 diabetes (11.1%) compared to participants without type 2 diabetes (88.9%) was significantly higher (1.99; CI = 1.15 - 3.44) when using MSM-Cox with IPTW after adjustments for clinical and sociodemographic risk factors. When applying Cox proportional hazard models adjusted for the same variables, the HR was lower and non-significant at 1.34 (CI = 0.94 - 1.98). CONCLUSIONS:This longitudinal study with four measurements assessed a possible causal association between type 2 diabetes and IHD by applying MSM-Cox with IPTW. Although causality cannot be determined due to the remaining risk of residual bias, the results may help to elucidate a potential causal relationship between type 2 diabetes and IHD. Further causal studies on possible underlying mechanisms are, however, needed.

Abstract Background Breast cancer is, despite screening, not always detected early enough and is together with other tumor types known to shed genetic information in circulation. Unlike single-copy nuclear DNA, mitochondrial DNA (mtDNA) copies range from 100s to 10,000s per cell, thus providing a potentially alternative to identify potential missing cancer information in circulation at an early stage. Methods To characterize mitochondrial mutation landscapes in breast cancer, whole mtDNA sequencing and bioinformatics analyses were performed on 86 breast cancer biopsies and 50 available matched baseline cancer-free whole blood samples from the same individuals, selected from a cohort of middle-aged women in Sweden. To determine whether the mutations can be detected in blood plasma prior to cancer diagnosis, we further designed a nested case-control study (n = 663) and validated the shortlisted mutations using droplet digital PCR. Results We detected different mutation landscapes between biopsies and matched whole blood samples. Compared to whole blood samples, mtDNA from biopsies had higher heteroplasmic mutations in the D-loop region (P = 0.02), RNR2 (P = 0.005), COX1 (P = 0.037) and CYTB (P = 0.006). Furthermore, the germline mtDNA mutations had higher heteroplasmy level than the lost (P = 0.002) and de novo mutations (P = 0.04). The nonsynonymous to synonymous substitution ratio (dN/dS) was higher for the heteroplasmic mutations (P = 7.25 × 10−12) than that for the homoplasmic mutations, but the de novo (P = 0.06) and lost mutations (P = 0.03) had lower dN/dS than the germline mutations. Interestingly, we found that the critical regions for mitochondrial transcription: MT-HSP1 (odds ratio [OR]: 21.41), MT-TFH (OR: 7.70) and MT-TAS2 (OR: 3.62), had significantly higher heteroplasmic mutations than the rest of the D-loop sub-regions. Finally, we found that the presence of mt.16093T > C mutation increases 67% risk of developing breast cancer. Conclusions Our findings show that mitochondrial genetic landscape changes during cancer pathogenesis and positive selection of mtDNA heteroplasmic mutations in breast cancer. Most importantly, the mitochondrial mutations identified in biopsies can be traced back in matched plasma samples and could potentially be used as early breast cancer diagnostic biomarkers.

BACKGROUND:The significant role of long non-coding 7S RNA in controlling mitochondrial transcription highlights its importance in mitochondrial function. Considering the suggested connection between mitochondrial dysfunction and the onset of mental disorders, this study aimed to explore the potential involvement of 7S RNA in the context of depression/anxiety. RESULTS:A total of 181 patients in primary health care (age 20-64 years) with depression/anxiety and 59 healthy controls were included in the study. 7S RNA was measured using quantitative real-time PCR in plasma samples collected before (baseline) and after 8 weeks of treatment (mindfulness or cognitive-based behavioral therapy). Upon adjustment for age and sex, the baseline plasma levels of 7S RNA were significantly higher in patients than in healthy controls (p < 0.001). Notably, post-treatment, there was a significant reduction in 7S RNA levels (p = 0.03). These changes in 7S RNA were related to the treatment response, as indicated by HADS-D (Hospital Anxiety and Depression Scale) scores (ß = -0.04, p = 0.04), even after accounting for baseline scores and other cofounders. CONCLUSION:The findings of this study indicate an association between plasma 7S RNA levels and depression/anxiety, as well as treatment response. While further confirmatory analyses are necessary, plasma 7S RNA holds promise as a potential predictive biomarker for both depression/anxiety and the treatment response within these disorders.

Background Abdominal aortic aneurysm (AAA) is a vascular disease with a mortality rate of >80% if ruptured. Mitochondrial dysfunction has been previously implicated in AAA pathogenesis. In this study, we aimed to characterize the mitochondrial genetic landscape in AAA. Methods and Results Whole mitochondrial genome sequencing and bioinformatics analysis were performed in comorbidity matched 48 cases without AAA and 48 cases with AAA, objectively diagnosed, and selected from a cohort of 65‐year‐old men recruited for a screening program. We identified differential mutational landscapes in men with and without AAA, with errors in mitochondrial DNA replication or repair as potential sources. Heteroplasmic insertions and overall heteroplasmy of structural rearrangements were significantly elevated in AAA cases. Three heteroplasmic variants were associated with risk factors of AAA: leukocyte concentration, plasma glucose, and cholesterol levels, respectively. Interestingly, mutations were more prevalent in regulatory part of the mitochondria, the displacement loop region, in AAA as compared with controls (P value <0.05), especially in the conserved and critical mitochondrial extended termination‐associated sequence region. Moreover, we report a novel 24 bp mitochondrial DNA duplication present exclusively in cases with AAA (4%) and 75% of the unmatched AAA biopsies. Finally, the haplogroup cluster JTU was overrepresented in AAA and significantly associated with a positive family history of AAA (odds ratio, 2.9 [95% CI, 1.1–8.1]). Conclusions This is the first study investigating the mitochondrial genome in AAA, where important genetic alterations and haplogroups associated with AAA and clinical risk factors were identified. Our findings have the potential to fill in gaps in the missing genetic information on AAA.

Background Mitochondrial dysfunction is a hallmark of cancer. However, it is unclear whether it is a cause of cancer. This two-sample Mendelian randomization (MR) analyses, uses genetic instruments to proxy the exposure of mitochondrial dysfunction and cancer summary statistics as outcomes, allowing for causal inferences.Methods Summary statistics from 18 common cancers (2107-491,974 participants), gene expression, DNA methylation and protein expression quantitative trait loci (eQTL, mQTL and pQTL, respectively, 1000-31,684 participants) on individuals of European ancestry, were included. Genetic variants located within or close to the 1136 mitochondrial-related genes (in cis) and robustly associated with the mitochondrial molecular alterations were used as instrumental variables, and their causal associations with cancers were examined using summary-data-based MR (SMR) analyses. An additional five MR methods were used as sensitivity analyses to confirm the casual associations. A Bayesian test for colocalization between mitochondrial molecular QTLs and cancer risk loci was performed to provide insights into the potential regulatory mechanisms of risk variants on cancers.Findings We identified potential causal relationships between mitochondrial-related genes and breast, prostate, gastric, lung cancer and melanoma by primary SMR analyses. The sensitivity and the colocalization analyses further refined four genes that have causal effects on three types of cancer. We found strong evidence of positive association of FDPS expression level with breast cancer risk (OR per SD, 0.66; 95% CI, 0.49-0.83; P = 9.77 x 10(-7)), NSUN4 expression level with both breast cancer risk (OR per SD, 1.05; 95% CI, 1.03-1.07; P = 5.24 x 10(-6)) and prostate cancer risk (OR per SD, 1.06; 95% CI, 1.03-1.09; P = 1.01 x 10(-5)), NSUN4 methylation level with both breast and prostate cancer risk, and VARS2 methylation level with lung cancer risk.Interpretations This data-driven MR study demonstrated the causal role of mitochondrial dysfunction in multiple cancers. Furthermore, this study identified candidate genes that can be the targets of potential pharmacological agents for cancer prevention.

The aims of the study were 1). to investigate the association between the potential risk factors including socio-demographic, lifestyle and DNA methylation and mental disorders in middle-aged women from a large population-based follow-up study, and 2). to estimate the risk score by combining the potential risk factors to examine the mental disorder's incidence. A total of 6461 women, aged 50-65 years, were included in the study. After a median follow-up of 17 years, 2026 (31%) women were diagnosed with mental disorders. The association between these factors and the risk of mental disorders was analyzed using Cox regression models. Harrell's concordance index (C-index) was used to quantify models' predictive performance for future mental disorders. Blood-based global DNA methylation was assessed by an enzyme-linked immunosorbent assay. We found that smoking (HR = 1.38, 95% CI: 1.24-1.54), less physical activity (HR = 1.33, 95% CI: 1.10-1.60), being single (HR = 1.16, 95% CI: 1.04-1.29) and unemployment (HR = 1.50, 95% CI: 1.33-1.70) were independently associated with an increased risk of overall mental disorders. Risk score models combining all these observed factors showed an increased risk, but the prediction ability was low, except for the risk of alcohol use disorders (AUD) and drug use disorders (DUD) (C-index = 0.8). Finally, women who developed MDD/anxiety during follow-up had significantly higher global DNA methylation at baseline than women who did not develop MDD/anxiety (p = 0.005). In conclusion, our results indicate that the studied risk factors were associated with mental disorders in a type-specific manner. The predictive model showed that smoking, alcohol consumption, education and physical activity may predict future AUD/DUD. Global DNA methylation may be a potential risk factor for MDD/anxiety incidence.

Background and aims: Mitochondrial DNA copy number (mtDNA-CN) is a surrogate biomarker of mitochondrial dysfunction and is associated with type 2 diabetes (T2D) and cardiovascular disease (CVD). However, despite being associated with both CVD and T2D, it is not known what role mtDNA-CN has in the association between T2D and CVD. Our aims were to investigate whether, (1) baseline mtDNA-CN is associated with CVD incidence and (2) mtDNA-CN has a role as a mediator between T2D and CVD. Method: We quantified absolute mtDNA-CN by droplet digital PCR method in a population-based follow-up study of middle aged (52-65 years) women (n = 3062). The median follow-up period was 17 years. Results: Our results show that low baseline levels of mtDNA-CN (< 111 copies/mu L) were associated with an increased risk of CVD (HR = 1.32, 95% CI = 1.08; 1.63) as well as with specific CVDs: coronary heart disease (HR = 1.28, 95% CI = 0.99; 1.66), stroke (HR = 1.26, 95% CI = 0.87; 1.84) and abdominal aortic aneurysm (HR = 2.61, 95% CI = 1.03; 6.62). The associations decreased but persisted even after adjustment for potential confounders. Furthermore, our results show that the total effect of T2D on future risk of CVD was reduced after controlling for mtDNA-CN and the proportion mediated by mtDNA-CN was estimated to be 4.9%. Conclusions: Lower baseline mtDNA-CN is associated with incident CVD and may have a mediating effect on the association between T2D and CVD; however, this novel observation needs to be confirmed in future studies.

Heart failure (HF) is a leading cause of death in both men and women. However, risk factors seem to differ for men and women and significant gaps in sex-specific knowledge exist. Mitochondria are critical for cardiomyocytes and in this study, we investigated the role of baseline mitochondrial DNA copy number (mtDNA-CN) in HF incidence in middle-aged women and its possible role in the association between myocardial infarction (MI) and HF. Finally, we also investigated whether baseline mtDNA-CN was associated with overall and HF mortality. Baseline levels of mtDNA-CN were quantified by droplet digital PCR in a population-based follow-up study of middle-aged (50–59 years) Swedish women ( n = 2,508). The median follow-up period was 17 years. Levels of mtDNA-CN were associated with age, BMI, alcohol, smoking, education, physical activity and lipid biomarkers. Multivariable Cox regression analysis adjusted for potential confounders showed that each standard deviation decrease of baseline mtDNA-CN was associated with higher incidence of HF (HR = 1.34; 95% CI=1.11–1.63). Similar results were obtained when mtDNA-CN levels were categorized into quartiles with lowest vs. highest quartile showing the highest risk of HF incidence (HR = 2.04 95% CI=1.14; 3.63). We could not detect any role of mtDNA-CN in the association between MI and HF incidence. Lower baseline mtDNA-CN levels were associated with both overall (HR = 1.27; 95% CI=1.10–1.46) and HF mortality (HR = 1.93; 95% CI=1.04–3.60); however, in multivariable analysis adjusted for potential confounders, the higher risks of HF mortality were no longer significant (HR=1.57; 95% CI=0.85–2.90). In conclusion, low baseline mtDNA-CN is an easily quantifiable molecular risk factor for HF incidence and may be a risk factor for overall and HF-related mortality.