Sune F. Nielsen

Rare variant in scavenger receptor BI raises HDL cholesterol and increases risk of coronary heart disease

A scavenger that protects the heart Coronary heart disease is a tale of two forms of plasma cholesterol. In contrast to the well-established effects of “bad” cholesterol (LDL-C), the role of “good” cholesterol (HDL-C) is mysterious. Elevated HDL-C correlates with a lower risk of heart disease, yet drugs that raise HDL-C levels do not reduce risk. Zanoni et al. found that some people with exceptionally high levels of HDL-C carry a rare sequence variant in the gene encoding the major HDL-C receptor, scavenger receptor BI. This variant destroys the receptors ability to take up HDL-C. Interestingly, people with this variant have a higher risk of heart disease despite having high levels of HDL-C. Science, this issue p. 1166 A human genetics study sheds light on how HDL (good) cholesterol protects against cardiovascular disease. Scavenger receptor BI (SR-BI) is the major receptor for high-density lipoprotein (HDL) cholesterol (HDL-C). In humans, high amounts of HDL-C in plasma are associated with a lower risk of coronary heart disease (CHD). Mice that have depleted Scarb1 (SR-BI knockout mice) have markedly elevated HDL-C levels but, paradoxically, increased atherosclerosis. The impact of SR-BI on HDL metabolism and CHD risk in humans remains unclear. Through targeted sequencing of coding regions of lipid-modifying genes in 328 individuals with extremely high plasma HDL-C levels, we identified a homozygote for a loss-of-function variant, in which leucine replaces proline 376 (P376L), in SCARB1, the gene encoding SR-BI. The P376L variant impairs posttranslational processing of SR-BI and abrogates selective HDL cholesterol uptake in transfected cells, in hepatocyte-like cells derived from induced pluripotent stem cells from the homozygous subject, and in mice. Large population-based studies revealed that subjects who are heterozygous carriers of the P376L variant have significantly increased levels of plasma HDL-C. P376L carriers have a profound HDL-related phenotype and an increased risk of CHD (odds ratio = 1.79, which is statistically significant).

Antihypertensive treatment and risk of atrial fibrillation: a nationwide study

AIMSnTo examine the associations between antihypertensive treatment with angiotensin-converting enzyme inhibitors (ACEis) or angiotensin receptor blockers (ARBs), β-blockers, diuretics, or calcium-antagonists, and risk of atrial fibrillation. We examined these associations using the entire Danish population from 1995 through 2010.nnnMETHODS AND RESULTSnExcluding medication used in atrial fibrillation, we matched individuals on ACEi monotherapy 1:1 with individuals on β-blocker (n = 48 658), diuretic (n = 69 630), calcium-antagonist (n = 57 646), and ARB monotherapy (n = 20 158). Likewise, individuals on ARB monotherapy were matched 1:1 with individuals on β-blocker (n = 20 566), diuretic (n = 20 832), calcium-antagonist (n = 20 232), and ACEi monotherapy (n = 20 158). All were free of atrial fibrillation and of predisposing diseases like heart failure, ischaemic heart disease, diabetes mellitus, and hyperthyroidism at baseline and none received any other antihypertensive medication. We studied risk of atrial fibrillation, and used risk of stroke, influenced by lowering blood pressure rather than renin-angiotensin system blockade per se, as an indicator of the importance of blood pressure lowering per se. Hazard ratios of atrial fibrillation for ACEi and ARB monotherapy were 0.12 (95% CI: 0.10-0.15) and 0.10 (0.07-0.14) compared with β-blocker, 0.51 (0.44-0.59) and 0.43 (0.32-0.58) compared with diuretic, and 0.97 (0.81-1.16) and 0.78 (0.56-1.08) compared with calcium-antagonist monotherapy. Risk of stroke did not differ among the five antihypertensive medications.nnnCONCLUSIONnUse of ACEis and ARBs compared with β-blockers and diuretics associates with a reduced risk of atrial fibrillation, but not stroke, within the limitations of a retrospective study reporting associations. This suggests that controlling activation of the renin-angiotensin system in addition to controlling blood pressure is associated with a reduced risk of atrial fibrillation.

Statin use before diabetes diagnosis and risk of microvascular disease: a nationwide nested matched study

BACKGROUNDnThe role of statins in the development of microvascular disease in patients with diabetes is unknown. We tested the hypothesis that statin use increases the risk of diabetic retinopathy, diabetic neuropathy, diabetic nephropathy, and gangrene of the foot in individuals with diabetes.nnnMETHODSnWe identified all patients living in Denmark who were aged 40 years or older and were diagnosed with incident diabetes between Jan 1, 1996, and Dec 31, 2009. We obtained patients data from the Danish Patient Registry and information on drug use from the Danish Registry of Medicinal Product Statistics. We randomly selected 15,679 individuals from the database who had used statins regularly until their diagnosis of diabetes (statin users) and matched them in a 1:3 ratio with 47,037 individuals who had never used statins before diagnosis (non-statin users). Our primary outcome was to compare the cumulative incidence of diabetic retinopathy, diabetic neuropathy, diabetic nephropathy, or gangrene of the foot in statin users versus non-statin users. We analysed data with Cox regression models, adjusted for covariates including sex, age at diabetes diagnosis, and method of diabetes diagnosis. To address potential biases between statin users and non-statin users, we made adjustments to our analysis with a propensity score and with other factors. Median follow-up was 2·7 years (range 0-13).nnnFINDINGSnDuring 215,725 person-years of follow-up, 2866 patients developed diabetic retinopathy, 1406 developed diabetic neuropathy, 1248 developed diabetic nephropathy, and 2392 developed gangrene of the foot. Compared with non-statin users, statin users had a lower cumulative incidence of diabetic retinopathy (hazard ratio 0·60, 95% CI 0·54-0·66; p<0·0001), diabetic neuropathy (0·66, 0·57-0·75; p<0·0001), and gangrene of the foot (0·88, 0·80-0·97; p=0·010), but not diabetic nephropathy (0·97, 0·85-1·10; p=0·62). These results were similar after adjusting for the competing risk of death, after matching for a propensity score, after adjusting for visits to a family doctor, and by stratification on covariates. The corresponding multivariable adjusted hazard ratio for risk of diabetes in the total population was 1·17 (95% CI 1·14-1·21; p<0·0001).nnnINTERPRETATIONnUse of statins before diagnosis of incident diabetes was not associated with an increased risk of microvascular disease. Whether statins are protective against some forms of microvascular disease-a possibility raised by these data-will need to be addressed in other studies similar to ours, in mendelian randomisation studies, and preferably in randomised controlled trials.nnnFUNDINGnHerlev Hospital, Copenhagen University Hospital.

Skin cancer as a marker of sun exposure associates with myocardial infarction, hip fracture and death from any cause

BACKGROUNDnSun exposure is the single most important risk factor for skin cancer, but sun exposure may also have beneficial effects on health. We tested the hypothesis that individuals with skin cancer (non-melanoma skin cancer and cutaneous malignant melanoma) have less myocardial infarction, hip fracture and death from any cause, compared with general population controls.nnnMETHODSnWe examined the entire Danish population above age 40 years from 1980 through 2006, comprising 4.4 million individuals. Diagnoses of non-melanoma skin cancer (n=129,206), cutaneous malignant melanoma (n=22,107), myocardial infarction (n=327,856), hip fracture (n=129,419), and deaths from any cause (n=1,629,519) were drawn from national registries.nnnRESULTSnIn individuals with vs without non-melanoma skin cancer, multifactorially adjusted odds ratios were 0.96 (95% confidence interval: 0.94-0.98) for myocardial infarction and 1.15 (1.12-1.18) for hip fracture, and the multifactorially adjusted hazard ratio was 0.52 (0.52-0.53) for death from any cause. Risk of hip fracture was reduced (odds ratios were below 1.0) in individuals below age 90 years. In individuals with vs without cutaneous malignant melanoma, corresponding odds ratios were 0.79 (0.74-0.84) for myocardial infarction and 0.84 (0.76-0.93) for hip fracture, and the corresponding hazard ratio for death from any cause was 0.89 (0.87-0.91); however, cutaneous malignant melanoma was associated positively with death from any cause in some individuals.nnnCONCLUSIONSnIn this nationwide study, having a diagnosis of skin cancer was associated with less myocardial infarction, less hip fracture in those below age 90 years and less death from any cause. Causal conclusions cannot be made from our data. A beneficial effect of sun exposure per se needs to be examined in other studies.

GUESS-ing polygenic associations with multiple phenotypes using a GPU-based evolutionary stochastic search algorithm

Genome-wide association studies (GWAS) yielded significant advances in defining the genetic architecture of complex traits and disease. Still, a major hurdle of GWAS is narrowing down multiple genetic associations to a few causal variants for functional studies. This becomes critical in multi-phenotype GWAS where detection and interpretability of complex SNP(s)-trait(s) associations are complicated by complex Linkage Disequilibrium patterns between SNPs and correlation between traits. Here we propose a computationally efficient algorithm (GUESS) to explore complex genetic-association models and maximize genetic variant detection. We integrated our algorithm with a new Bayesian strategy for multi-phenotype analysis to identify the specific contribution of each SNP to different trait combinations and study genetic regulation of lipid metabolism in the Gutenberg Health Study (GHS). Despite the relatively small size of GHS (nu200a=u200a3,175), when compared with the largest published meta-GWAS (n>100,000), GUESS recovered most of the major associations and was better at refining multi-trait associations than alternative methods. Amongst the new findings provided by GUESS, we revealed a strong association of SORT1 with TG-APOB and LIPC with TG-HDL phenotypic groups, which were overlooked in the larger meta-GWAS and not revealed by competing approaches, associations that we replicated in two independent cohorts. Moreover, we demonstrated the increased power of GUESS over alternative multi-phenotype approaches, both Bayesian and non-Bayesian, in a simulation study that mimics real-case scenarios. We showed that our parallel implementation based on Graphics Processing Units outperforms alternative multi-phenotype methods. Beyond multivariate modelling of multi-phenotypes, our Bayesian model employs a flexible hierarchical prior structure for genetic effects that adapts to any correlation structure of the predictors and increases the power to identify associated variants. This provides a powerful tool for the analysis of diverse genomic features, for instance including gene expression and exome sequencing data, where complex dependencies are present in the predictor space.

Investigation of gene‐environment interactions between 47 newly identified breast cancer susceptibility loci and environmental risk factors

A large genotyping project within the Breast Cancer Association Consortium (BCAC) recently identified 41 associations between single nucleotide polymorphisms (SNPs) and overall breast cancer (BC) risk. We investigated whether the effects of these 41 SNPs, as well as six SNPs associated with estrogen receptor (ER) negative BC risk are modified by 13 environmental risk factors for BC. Data from 22 studies participating in BCAC were pooled, comprising up to 26,633 cases and 30,119 controls. Interactions between SNPs and environmental factors were evaluated using an empirical Bayes‐type shrinkage estimator. Six SNPs showed interactions with associated p‐values (pint) <1.1 × 10−3. None of the observed interactions was significant after accounting for multiple testing. The Bayesian False Discovery Probability was used to rank the findings, which indicated three interactions as being noteworthy at 1% prior probability of interaction. SNP rs6828523 was associated with increased ER‐negative BC risk in women ≥170 cm (OR = 1.22, p = 0.017), but inversely associated with ER‐negative BC risk in women <160 cm (OR = 0.83, p = 0.039, pint = 1.9 × 10−4). The inverse association between rs4808801 and overall BC risk was stronger for women who had had four or more pregnancies (OR = 0.85, p = 2.0 × 10−4), and absent in women who had had just one (OR = 0.96, p = 0.19, pint = 6.1 × 10−4). SNP rs11242675 was inversely associated with overall BC risk in never/former smokers (OR = 0.93, p = 2.8 × 10−5), but no association was observed in current smokers (OR = 1.07, p = 0.14, pint = 3.4 × 10−4). In conclusion, recently identified BC susceptibility loci are not strongly modified by established risk factors and the observed potential interactions require confirmation in independent studies.

Susceptibility to chronic mucus hypersecretion, a genome wide association study.

Background Chronic mucus hypersecretion (CMH) is associated with an increased frequency of respiratory infections, excess lung function decline, and increased hospitalisation and mortality rates in the general population. It is associated with smoking, but it is unknown why only a minority of smokers develops CMH. A plausible explanation for this phenomenon is a predisposing genetic constitution. Therefore, we performed a genome wide association (GWA) study of CMH in Caucasian populations. Methods GWA analysis was performed in the NELSON-study using the Illumina 610 array, followed by replication and meta-analysis in 11 additional cohorts. In total 2,704 subjects with, and 7,624 subjects without CMH were included, all current or former heavy smokers (≥20 pack-years). Additional studies were performed to test the functional relevance of the most significant single nucleotide polymorphism (SNP). Results A strong association with CMH, consistent across all cohorts, was observed with rs6577641 (pu200a=u200a4.25×10−6, ORu200a=u200a1.17), located in intron 9 of the special AT-rich sequence-binding protein 1 locus (SATB1) on chromosome 3. The risk allele (G) was associated with higher mRNA expression of SATB1 (4.3×10−9) in lung tissue. Presence of CMH was associated with increased SATB1 mRNA expression in bronchial biopsies from COPD patients. SATB1 expression was induced during differentiation of primary human bronchial epithelial cells in culture. Conclusions Our findings, that SNP rs6577641 is associated with CMH in multiple cohorts and is a cis-eQTL for SATB1, together with our additional observation that SATB1 expression increases during epithelial differentiation provide suggestive evidence that SATB1 is a gene that affects CMH.

Statin Use Is Associated with Reduced Mortality in Patients with Interstitial Lung Disease

Introduction We hypothesized that statin use begun before the diagnosis of interstitial lung disease is associated with reduced mortality. Methods We studied all patients diagnosed with interstitial lung disease in the entire Danish population from 1995 through 2009, comparing statin use versus no statin use in a nested 1:2 matched study. Results The cumulative survival as a function of follow-up time from the date of diagnosis of interstitial lung disease (n = 1,786+3,572) and idiopathic lung fibrosis (n = 261+522) was higher for statin users versus never users (log-rank: P = 7·10−9 and P = 0.05). The median survival time in patients with interstitial lung disease was 3.3 years in statin users and 2.1 years in never users. Corresponding values in patients with idiopathic lung fibrosis were 3.4 versus 2.4 years. After multivariable adjustment, the hazard ratio for all-cause mortality for statin users versus never users was 0.73 (95% confidence interval, 0.68 to 0.79) in patients with interstitial lung disease and 0.76 (0.62 to 0.93) in patients with idiopathic lung fibrosis. Results were robust in all sensitivity analyses. Conclusion Among patients with interstitial lung disease statin use was associated with reduced all-cause mortality.

Increased Rheumatoid Factor and Deep Venous Thrombosis: 2 Cohort Studies of 54628 Individuals from the General Population

BACKGROUNDnThe risk of deep venous thrombosis is increased in patients with rheumatoid arthritis. We tested the hypothesis that increased concentrations of rheumatoid factor are associated with increased risk of deep venous thrombosis in individuals without autoimmune rheumatic disease in the general population.nnnMETHODSnWe included 54628 participants from the Copenhagen City Heart Study (1981-83) and the Copenhagen General Population Study (2004-12), all with a measured concentration of IgM rheumatoid factor and without autoimmune rheumatic disease or venous thromboembolism. The main outcome was incident deep venous thrombosis. There were no losses to follow-up.nnnRESULTSnDuring 368381 person-years, 670 individuals developed deep venous thrombosis. A rheumatoid factor concentration ≥ vs <110 IU/mL showed the strongest association with deep venous thrombosis, with multivariable adjusted hazard ratios of 9.0 (95% CI 3.1-26) for 1-year follow-up, 4.3 (2.2-8.5) for 5-year follow-up, and 3.1 (1.7-5.6) for up to 32 years of follow-up. Compared with rheumatoid factor concentrations <15 IU/mL, the multivariable adjusted hazard ratios for deep venous thrombosis during maximum follow-up were 1.3 (1.0-1.5) for 15-29 IU/mL, 1.7 (1.0-2.8) for 30-59 IU/mL, 2.4 (1.3-4.3) for 60-119 IU/mL, and 3.0 (1.6-5.6) for ≥120 IU/mL (trend P = 6 × 10(-7)). Results were similar in the 2 studies separately. Obese men and women age >60 years with rheumatoid factor concentrations ≥120 IU/mL had 10% and 8% 5-year risk of deep venous thrombosis.nnnCONCLUSIONSnIncreased rheumatoid factor in the general population was associated with up to 3-fold increased long-term risk and up to 9-fold increased 1-year risk of deep venous thrombosis.

Genetic variants affecting cross-sectional lung function in adults show little or no effect on longitudinal lung function decline

Background Genome-wide association studies have identified numerous genetic regions that influence cross-sectional lung function. Longitudinal decline in lung function also includes a heritable component but the genetic determinants have yet to be defined. Objectives We aimed to determine whether regions associated with cross-sectional lung function were also associated with longitudinal decline and to seek novel variants which influence decline. Methods We analysed genome-wide data from 4167 individuals from the Busselton Health Study cohort, who had undergone spirometry (12u2005695 observations across eight time points). A mixed model was fitted and weighted risk scores were calculated for the joint effect of 26 known regions on baseline and longitudinal changes in FEV1 and FEV1/FVC. Potential additional regions of interest were identified and followed up in two independent cohorts. Results The 26 regions previously associated with cross-sectional lung function jointly showed a strong effect on baseline lung function (p=4.44×10−16 for FEV1/FVC) but no effect on longitudinal decline (p=0.160 for FEV1/FVC). This was replicated in an independent cohort. 39 additional regions of interest (48 variants) were identified; these associations were not replicated in two further cohorts. Conclusions Previously identified genetic variants jointly have a strong effect on cross-sectional lung function in adults but little or no effect on the rate of decline of lung function. It is possible that they influence COPD risk through lung development. Although no genetic variants have yet been associated with lung function decline at stringent genome-wide significance, longitudinal change in lung function is heritable suggesting that there is scope for future discoveries.