Catherine E. de Keyser

Pharmacogenetic meta-analysis of genome-wide association studies of LDL cholesterol response to statins

Statins effectively lower LDL cholesterol levels in large studies and the observed interindividual response variability may be partially explained by genetic variation. Here we perform a pharmacogenetic meta-analysis of genome-wide association studies (GWAS) in studies addressing the LDL cholesterol response to statins, including up to 18,596 statin-treated subjects. We validate the most promising signals in a further 22,318 statin recipients and identify two loci, SORT1/CELSR2/PSRC1 and SLCO1B1, not previously identified in GWAS. Moreover, we confirm the previously described associations with APOE and LPA. Our findings advance the understanding of the pharmacogenetic architecture of statin response.

Total dietary antioxidant capacity, individual antioxidant intake and breast cancer risk: the Rotterdam Study.

Some studies suggest a favorable role of antioxidants on breast cancer risk but this is still inconclusive. The aim of this study was to assess whether overall dietary antioxidant capacity, as assessed by dietary ferric reducing antioxidant potential (FRAP), and individual dietary antioxidant intake were associated with breast cancer risk. Data was used from women participating in the Rotterdam Study, a prospective cohort study among subjects aged 55 years and older (N = 3,209). FRAP scores and antioxidant intake (i.e., vitamin A, C, E, selenium, flavonoids and carotenoids) was assessed at baseline by a food frequency questionnaire. Incident cases of breast cancer were confirmed through medical reports. During a median follow‐up of 17 years, 199 cases with breast cancer were identified. High dietary FRAP score was associated with a lower risk of breast cancer [hazard ratio (HR): 0.68; 95% confidence intervals (CI): 0.49, 0.96]. No overall association between individual antioxidant intake and breast cancer risk was found. However, low intake of alpha carotene and beta carotene was associated with a higher risk of breast cancer among smokers (HR: 2.48; 95% CI: 1.21, 5.12 and HR: 2.31; 95% CI: 1.12, 4.76 for alpha and beta carotene, respectively) and low intake of flavonoids was associated with breast cancer risk in women over the age of 70 (HR: 1.80; 95% CI: 1.09, 2.99). These results suggest that high overall dietary antioxidant capacity is associated with a lower risk of breast cancer. Individual effects of dietary carotenoids and dietary flavonoids may be restricted to subgroups such as smokers and elderly.

The SLCO1B1 c.521T>C polymorphism is associated with dose decrease or switching during statin therapy in the Rotterdam Study.

Objective The SLCO1B1 c.521T>C polymorphism is associated with statin plasma levels and simvastatin-induced adverse drug reactions. We studied whether the c.521T>C polymorphism is associated with dose decreases or switches to other cholesterol-lowering drugs during simvastatin and atorvastatin therapy, because these events are indicators of adverse drug reactions. Materials and methods We identified 1939 incident simvastatin and atorvastatin users in the Rotterdam Study, a population-based cohort study. Associations were studied using Cox proportional hazards analysis. Meta-analysis was performed with data from the Utrecht Cardiovascular Pharmacogenetics study. Results Simvastatin users with the c.521 CC genotype had a significantly higher risk of a dose decrease or switch than users with the TT genotype [hazard ratio (HR) 1.74, 95% confidence interval (CI) 1.05–2.88]. Female sex, age below 70 years, and low starting dose were risk factors. In atorvastatin users with starting dose of more than 20 mg, the risk of a dose decrease or switch was higher in users carrying a C allele than in users with the TT genotype (HR 3.26, 95% CI 1.47–7.25). In the meta-analysis the association in simvastatin users remained, with a significantly higher risk of a dose decrease or switch in simvastatin users with two minor alleles (HR 1.69, 95% CI 1.05–2.73). For atorvastatin users no significant association was found. Conclusion In simvastatin users in the Rotterdam Study, we demonstrated an association between the c.521T>C polymorphism and dose decrease or switching, as indicators of adverse drug reactions, and provided risk factors for this association. For atorvastatin, an association was found in users with a starting dose of more than 20 mg.

Detection bias may be the main cause of increased cancer incidence among diabetics: Results from the Rotterdam Study

AIM Type 2 diabetes is associated with an increased cancer risk. Most studies on this topic analyse diabetes as a risk factor without adjusting for diabetes duration before cancer occurrence. This study aimed to investigate the association between diabetes duration and cancer risk in more detail. METHODS In this prospective cohort study, diabetes diagnosis was based on clinical information and use of glucose lowering medication. Details on incident cancers were obtained via general practitioners and linkage to pathology registers. Cox proportional hazards models were used with onset and duration of diabetes as time-varying determinants. RESULTS The study comprised 10,181 individuals. Diabetes was associated with an increased overall risk of incident cancers (hazard ratio (HR) 1.2, 95% confidence interval (CI) 1.07-1.39) and pancreatic cancer (HR 2.9, 95% CI 1.75-4.89). A diagnosis of diabetes less than three months before the diagnosis of cancer was associated with strongly increased risks of all- (HR 3.3, 95% CI 2.50-4.32) and pancreatic cancers (HR 28.7, 95% CI 6.32-130.58). CONCLUSION The magnitude of the association between diabetes and an increased risk of cancer seems to be inflated by detection- or protopathic bias. Future studies investigating this association should adjust for diabetes duration and include a plausible aetiological risk window.

Statin therapy is associated with a reduced risk of non-alcoholic fatty liver in overweight individuals.

BACKGROUND Non-alcoholic fatty liver or hepatic steatosis is considered the hepatic manifestation of the metabolic syndrome. Statins are often used by patients with metabolic syndrome, but their effect in steatosis is not well established. AIMS To study the association between statins and the presence of steatosis. METHODS In the population-based Rotterdam Study, 2578 subjects underwent liver ultrasonography and had prescription data available. In a cross-sectional design, we investigated the effect of current, past, and duration of statin use. Logistic regression analyses were adjusted for age, sex, and other known risk factors. RESULTS The prevalence of steatosis was 35.3%. We identified 631 current and 359 past statin users. In multivariable analyses, current statin use >2 years was associated with a significantly lower steatosis prevalence [OR 0.43, 95% CI 0.19-0.96]. Stratification by mean body mass index showed that this association was stronger in patients with body mass index ≥ 27.5 [OR 0.30, 95% CI 0.11-0.81 for current use >2 years], while in patients with body mass index <27.5 the association was non-significant. CONCLUSION Within the Rotterdam study, in patients with body mass index ≥ 27.5 current use of statins for >2 years was associated with a lower prevalence of steatosis.

Meta-analysis of genome-wide association studies of HDL cholesterol response to statins.

Background In addition to lowering low density lipoprotein cholesterol (LDL-C), statin therapy also raises high density lipoprotein cholesterol (HDL-C) levels. Inter-individual variation in HDL-C response to statins may be partially explained by genetic variation. Methods and results We performed a meta-analysis of genome-wide association studies (GWAS) to identify variants with an effect on statin-induced high density lipoprotein cholesterol (HDL-C) changes. The 123 most promising signals with p<1×10−4 from the 16 769 statin-treated participants in the first analysis stage were followed up in an independent group of 10 951 statin-treated individuals, providing a total sample size of 27 720 individuals. The only associations of genome-wide significance (p<5×10−8) were between minor alleles at the CETP locus and greater HDL-C response to statin treatment. Conclusions Based on results from this study that included a relatively large sample size, we suggest that CETP may be the only detectable locus with common genetic variants that influence HDL-C response to statins substantially in individuals of European descent. Although CETP is known to be associated with HDL-C, we provide evidence that this pharmacogenetic effect is independent of its association with baseline HDL-C levels.

Use of statins is associated with lower serum total and non-sex hormone-binding globulin-bound testosterone levels in male participants of the Rotterdam Study

OBJECTIVE Statins, or HMG-CoA reductase inhibitors, decrease cholesterol production. Because cholesterol is a precursor of the testosterone biosynthesis pathway, there is some concern that statins might lower serum testosterone levels. The objective of the present study was to investigate the association between the use of statins and serum testosterone levels in men. DESIGN Cross-sectional study within the prospective population-based Rotterdam Study. SUBJECTS AND METHODS We included 4166 men with available data on total testosterone, non-sex hormone-binding globulin (SHBG)-bound testosterone, and medication use. Multivariable linear regression analysis was used to compare the differences in serum testosterone levels (nmol/l) between current, past, and never statin users. We considered dose and duration of use. Analyses were adjusted for age, BMI, cardiovascular disease, diabetes mellitus, hypertension, and estradiol levels. RESULTS We identified 577 current (mean age 64.1 years), 148 past (mean age 64.6 years), and 3441 never (mean age 64.6 years) statin users. Adjusted for all covariables, current statin use of 1-≤ 6 months or >6 months was significantly associated with lower total testosterone levels as compared to non-users (β -1.24, 95% CI -2.17, -0.31, and β -1.14, 95% CI -2.07, -0.20 respectively). Current use of 1-≤ 6 months was also associated with significantly lower non-SHBG-bound testosterone levels (β -0.42, 95% CI -0.82, -0.02). There was a trend toward lower testosterone levels at higher statin doses both for total (P(trend) 2.9 × 10(-5)) and non-SHBG-bound (P(trend) 2.0 × 10(-4)) testosterone. No association between past statin use and testosterone levels was found. CONCLUSION We showed that current use of statins was associated with significantly lower serum total and non-SHBG-bound testosterone levels. The clinical relevance of this association should be further investigated.

Dietary Fiber Intake Modifies the Positive Association between n–3 PUFA Intake and Colorectal Cancer Risk in a Caucasian Population

BACKGROUND The association between dietary fat intake and the risk of colorectal cancer (CRC) is still unclear. OBJECTIVES We analyzed whether intakes of dietary polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SFAs) were associated with CRC risk and whether these associations were modified by dietary fiber (DF) intake. METHODS This study was embedded in the Rotterdam Study, a prospective cohort study among subjects aged ≥55 y (n = 4967). At baseline, diet was measured by a food-frequency questionnaire. CRC events were diagnosed on the basis of pathology data and medical records. Multivariable adjusted HRs were calculated using Cox regression models. RESULTS During a mean follow-up period of 14.6 y, we identified 222 incident cases of CRC. There was no association between total PUFA, n-6 (ω-6) PUFA, or SFA intake and CRC risk. n-3 PUFA intake was associated with an increased risk of CRC [tertile 3 vs. tertile 1: HR = 1.44 (95% CI: 1.02, 2.04), P-trend = 0.04]. When data were analyzed by food sources, only n-3 PUFAs from nonmarine sources were associated with an increased risk of CRC. A significant interaction between n-3 PUFA and DF intakes was found (P-interaction = 0.02). After stratification by median DF intake, an increased risk of CRC caused by n-3 PUFA intake was observed in participants with a DF intake less than the median [tertile 3 vs. tertile 1: HR = 1.96 (95% CI: 1.20, 3.19), P-trend = 0.01]. No association was observed in subjects with DF intake equal to or higher than the median. CONCLUSIONS This study suggests that intake of n-3 PUFAs by adults is associated with an increased risk of CRC, which may be driven mainly by sources other than fish. Moreover, a complex interaction with DF intake may be present.

Genetic Variation in the PPARA Gene Is Associated with Simvastatin-Mediated Cholesterol Reduction in the Rotterdam Study

AIM Recently, minor alleles of two strongly linked polymorphisms in the PPARA gene, rs4253728 G>A and rs4823613 A>G, were related to decreased CYP3A4 expression and activity. We studied whether they were associated with the cholesterol-lowering effect of simvastatin. MATERIALS & METHODS We identified 123 incident users with cholesterol measurements before and after starting statin therapy in a prospective population-based cohort study. Associations between PPARA polymorphisms and change in total and low-density lipoprotein (LDL)-cholesterol levels were analyzed using linear regression. RESULTS The minor G allele of the rs4823613 A>G polymorphism was associated with a 0.258 mmol/l (95% CI: -0.470 to -0.046) and a 0.294 mmol/l (95% CI: -0.495 to -0.093) larger reduction in total and LDL-cholesterol, respectively, after starting simvastatin therapy. Results were similar for the rs4253728 G>A polymorphism. CONCLUSION The minor alleles of the PPARA rs4253728 and rs4823613 polymorphisms are associated with a better total and LDL-cholesterol-lowering response to simvastatin, possibly through influence on CYP3A4.

The rs13064411 polymorphism in the WDR52 gene, associated with PCSK9 levels, modifies statin-induced changes in serum total and LDL cholesterol levels

Objective Recently, the minor allele of the rs13064411A>G polymorphism in the WD repeat domain 52 (WDR52) gene was associated with increased statin-induced proprotein convertase subtilisin/kexin type 9 (PCSK9) levels and with LDL cholesterol response to statins. PCSK9 promotes LDL receptor degradation, leading to increased serum LDL cholesterol. We investigated whether the polymorphism was associated with cholesterol response to statins. Methods We identified 1105 current, 322 past, and 4831 never statin users during follow-up in the prospective population-based Rotterdam Study. The mean delta total, LDL, and HDL cholesterol levels between current and no current statin users with the same number of minor alleles were analyzed using random-effect repeated measurements. We adjusted for age, sex, number of cholesterol measurements, and follow-up time. Results Compared with no users with the same genotype, current statin users carrying a minor allele showed a statistically significantly lower delta total and LDL cholesterol compared with reference homozygous major allele carriers [total: &Dgr;=0.551 mmol/l (AG+GG) vs. &Dgr;=0.732 mmol/l (AA), Pinteraction: 5.2×10–7; LDL: &Dgr;=0.566 mmol/l (AG+GG) vs. &Dgr;=0.720 mmol/l (AA), Pinteraction: 1.8×10–5]. The effect was stronger in women (Pinteraction: 2.0×10–5 for LDL cholesterol, 8.0×10–6 for total cholesterol) and in high-dose users (defined daily doses>1.00) (Pinteraction: 7.0×10–5 for LDL cholesterol, Pinteraction: 0.081 for total cholesterol). The polymorphism was not associated with HDL cholesterol in current statin users, or with total, LDL and HDL cholesterol in never statin users. Conclusion The minor G allele of the rs13064411 polymorphism, associated with statin-induced PCSK9-levels, was associated with a decreased LDL-lowering and total cholesterol-lowering response to statins.