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Background: Plasma amyloid-β (Aβ) levels are increasingly studied as a potential, accessible marker of cognitive impairment and dementia. The most common plasma Aβ isoforms, i.e., Aβ1-40 and Aβ1-42 have been linked with risk of Alzheimer's disease. However, it remains under-explored whether plasma Aβ levels including novel Aβ1-38 relate to vascular brain disease and cognition in a preclinical-phase of dementiaObjective:To examine the association of plasma Aβ levels (i.e., Aβ1-38, Aβ1-40, and Aβ1-42) with markers of cerebral small vessel disease (SVD) and cognition in a large population-based setting.Methods: We analyzed plasma Aβ1 levels in 1201 subjects from two independent cohorts of the Rotterdam Study. Markers of SVD [lacunes, white matter hyperintensity (WMH) volume] were assessed on brain MRI (1.5T). Cognition was assessed by a detailed neuropsychological battery. In each cohort, the association of Aβ levels with SVD and cognition was performed using regression models. Estimates were then pooled across cohorts using inverse variance meta-analysis with fixed effects.Results: Higher levels of plasma Aβ1-38, Aβ1-40, Aβ1-42, and Aβ1-40/ Aβ1-42 ratio were associated with increasing lacunar and microbleeds counts. Moreover, higher levels of Aβ1-40 and Aβ1-40/ Aβ1-42 were significantly associated with larger WMH volumes. With regard to cognition, a higher level of Aβ1-38 Aβ1-40 and Aβ1-40/ Aβ1-42 was related to worse performance on cognitive test specifically in memory domain.Conclusion: Higher plasma levels of Aβ levels are associated with subclinical markers of vascular disease and poorer memory. Plasma Aβ levels thus mark the presence of vascular brain pathology. [ABSTRACT FROM AUTHOR]

Although genome-wide association studies (GWAS) have identified many common variants associated with complex traits, low-frequency and rare variants have not been interrogated in a comprehensive manner. Imputation from dense reference panels, such as the 1000 Genomes Project (1000G), enables testing of ungenotyped variants for association. Here we present the results of imputation using a large, new population-specific panel: the Genome of The Netherlands (GoNL). We benchmarked the performance of the 1000G and GoNL reference sets by comparing imputation genotypes with 'true' genotypes typed on ImmunoChip in three European populations (Dutch, British, and Italian). GoNL showed significant improvement in the imputation quality for rare variants (MAF 0.05-0.5%) compared with 1000G. In Dutch samples, the mean observed Pearson correlation, r2, increased from 0.61 to 0.71. We also saw improved imputation accuracy for other European populations (in the British samples, r2 improved from 0.58 to 0.65, and in the Italians from 0.43 to 0.47). A combined reference set comprising 1000G and GoNL improved the imputation of rare variants even further. The Italian samples benefitted the most from this combined reference (the mean r2 increased from 0.47 to 0.50). We conclude that the creation of a large population-specific reference is advantageous for imputing rare variants and that a combined reference panel across multiple populations yields the best imputation results. [ABSTRACT FROM AUTHOR]

Background: The enzyme CYP1A2 (cytochrome 1A2) is involved in the metabolism of certain drugs and caffeine, and its activity can be influenced by factors such as sex, age, and smoking. The single nucleotide polymorphism (SNP) rs762551A>C, which has also been studied for its modifying effect on cardiovascular disease, has been reported to alter enzyme activity. Objective: The objective was to study the effect of CYP1A2, sex, age, and smoking on coffee intake. Design: Within the Rotterdam Study, a population-based cohort, all coffee drinkers for whom genome-wide association data were available were selected. Because SNP rs762551 was not on the Illumina 550 platform, SNP rs2472299 was used as a proxy, with the A alíele of rs762551 linked to the G alíele of rs2472299. Linear regression analyses were used to determine the effect and interaction of rs2472299, sex, age, and smoking on coffee intake. Adjusted geometric means of coffee intake were calculated per genotype for the different smoking and sex strata by using multivariable general linear models. A combined analysis, with the use of a "risk score," was performed to determine the contribution of each separate factor. Results: rs2472299G>A, female sex, and nonsmoking were significantly inversely related to coffee intake. Coffee intake was lowest in nonsmoking women homozygous for rs2472299G>A (3.49 cups/d; ∼436 mL). All factors contributed almost linearly to the intake of coffee, with the highest coffee intake in smoking men without the A alíele (5.32 cups/d; ∼665 mL). Conclusion: rs2472299G>A, linked to rs762551A>C, sex, age, and smoking significantly contribute to coffee intake. Am J Clin Nutr 2012;96:182-7. [ABSTRACT FROM AUTHOR]

OBJECTIVE--SIRT1 has pleiotropic metabolic functions. We investigated whether SIRT1 genetic variation is associated with obesity. RESEARCH DESIGN AND METHODS--In 6,251 elderly subjects from the prospective, population-based Rotterdam Study, three single nucleotide polymorphisms (SNPs) in the SIRT1 gene were studied in relation to BMI and risk of obesity (BMI ≥30 kg/m²) and prospectively with BMI change after 6.4 years of follow-up. We used cross-sectional data from 2,347 participants from the Erasmus Rucphen Family (ERF) study for replication. RESULTS--Minor alleles of rs7895833 (G = 20.2%) and rs1467568 (A = 36.8%) were associated with lower BMI in the Rotterdam Study (P = 0.02 and 0.04) and in the replication cohort ERF study (P = 0.03 and 0.008) and in both studies combined (P = 0.002 for both SNPs), with a 0.2-0.4 kg/m² decrease in BMI per allele copy. Carriers of these alleles had 13-18% decreased risk of obesity (for rs7895833 in the Rotterdam Study: odds ratio 0.79 [95% CI 0.67-0.94], P = 0.007; in the ERF study: 0.93 [0.73-1.19], P = 0.37; and in the studies combined 0.87 [0.77-0.97], P = 0.02; for rs1467568 in the Rotterdam Study: 0.80 [0.68-0.94], P = 0.007; in the ERF study: 0.85 [0.72-0.99], P = 0.04; and in the studies combined: 0.82 [0.73-0.92], P = 0.0009). In the Rotterdam Study, the two variants were also associated with a lower BMI increase during 6.4 years of follow-up (P = 0.01 and 0.08). CONCLUSIONS--Two common variants in SIRT1 are associated with lower BMI in two independent Dutch populations. Carriers of these variants have 13-18% decreased risk of obesity and gain less weight over time. The availability of SIRT1 stimulators makes these findings relevant in light of the growing obesity epidemic. Diabetes 58:2828-2834, 2009 [ABSTRACT FROM AUTHOR]

Attention deficit/hyperactivity disorder (ADHD) is a common, highly heritable, neuropsychiatric disorder among children. Linkage studies in isolated populations have proved powerful to detect variants for complex diseases, such as ADHD. We performed a genome-wide linkage scan for ADHD in nine patients from a genetically isolated population in the Netherlands, who were linked to each other within 10 generations through multiple lines of descent. The genome-wide scan was performed with a set of 400 microsatellite markers with an average spacing of ±10–12 cM. We performed multipoint parametric linkage analyses using both recessive and dominant models. Our genome scan pointed to several chromosomal regions that may harbour ADHD susceptibility genes. None exceeded the empirical genome-wide significance threshold, but the Log of odds (LOD) scores were >1.5 for regions 6p22 (Heterogenetic log of odds (HLOD)=1.67) and 18q21–22 (HLOD=2.13) under a recessive model. We followed up these two regions in a larger sample of ADHD patients (n=21, 9 initial and 12 extra patients). The LOD scores did not increase after increasing the sample size (6p22 (HLOD=1.51), 18q21–22 (HLOD=1.83)). However, the LOD score on 6p22 increased to 2 when a separate analysis was performed for the inattentive type ADHD children. The linkage region on chromosome 18q overlaps with the findings of association of rs2311120 (P=10−5) and rs4149601 (P=10−4) in the genome-wide association analysis for ADHD performed by the Genetic Association Information Network consortium. Furthermore, there was an excess of regions harbouring serotonin receptors (HTR1B, HTR1E, HTR4, HTR1D, and HTR6) that showed a LOD score >1 in our genome-wide scan.European Journal of Human Genetics (2009) 17, 958–966; doi:10.1038/ejhg.2008.260; published online 21 January 2009 [ABSTRACT FROM AUTHOR]

Objective: To explore the association between polymorphisms in the complement component 3 (C3) gene and age-related macular degeneration (AMD), and to investigate the modifying effect of complement factor H (CFH) Y402H, LOC387715 A69S and smoking. Design: Pooled data from the prospective, population-based Rotterdam Study (enrolment between 1990 and 1993, and 3 follow-up examinations between September 1, 1993, and December 31, 2004) and an independent case-control study from the Netherlands. Participants: The Rotterdam Study comprised a total of 6418 persons aged ≥55 years who had gradable fundus photographs. The case-control study consisted of 357 unrelated AMD patients and 173 control individuals aged ≥55 years. Methods: The variants R102G and P314L of the C3 gene, CFH Y402H and LOC387715 A69S, were genotyped in all study participants. Information on cigarette smoking was obtained by interview at baseline. Main Outcome Measures: Early and late stages of prevalent and incident AMD, graded according to the international classification and grading system for AMD. Results: We found a population frequency of 0.217 for R102G and 0.211 for P314L in the Rotterdam Study. Both alleles significantly increased the risk of early AMD and all subtypes of late AMD, and this risk seemed to be independent of CFH Y402H, LOC387715 A69S, and smoking. Detailed analysis showed that the haplotype carrying both alleles had the highest frequency difference between cases and controls (P = 0.006). We estimated a total population-attributable risk of 14.6%. A meta-analysis of all currently available data yielded a pooled odds ratio (OR) of 1.61 (95% confidence interval [CI], 1.46–1.78) for the R102G allele, and an OR of 1.50 (95% CI, 1.31–1.71) for the P314L allele. Conclusions: Our study showed a significant association between variants in the C3 gene and AMD and further highlights the crucial role of the complement pathway in the etiology of AMD. Financial Disclosure(s): The authors have no proprietary or commercial interest in any materials discussed in this article. [Copyright &y& Elsevier]

OBJECTIVE--Prediction of type 2 diabetes based on genetic testing might improve identification of high-risk subjects. Genome-wide association (GWA) studies identified multiple new genetic variants that associate with type 2 diabetes. The predictive value of genetic testing for prediction of type 2 diabetes in the general population is unclear. RESEARCH DESIGN AND METHODS--We investigated 18 polymorphisms from recent GWA studies on type 2 diabetes in the Rotterdam Study, a prospective, population-based study among homogeneous Caucasian individuals of 55 years and older (genotyped subjects, n = 6,544; prevalent cases, n = 686; incident cases during follow-up, n = 601; mean follow-up 10.6 years). The predictive value of these polymorphisms was examined alone and in addition to clinical characteristics using logistic and Cox regression analyses. The discriminative accuracy of the prediction models was assessed by the area under the receiver operating characteristic curves (AUCs). RESULTS--Of the 18 polymorphisms, the ADAMTS9, CDKAL1, CDKN2A/B-rs1412829, FTO, IGF2BP2, JAZF1, SLC30A8, TCFTL2, and WFS1 variants were associated with type 2 diabetes risk in our population. The AUC was 0.60 (95% CI 0.57-0.63) for prediction based on the genetic polymorphisms; 0.66 (0.63-0.68) for age, sex, and BMI; and 0.68 (0.66-0.71) for the genetic polymorphisms and clinical characteristics combined. CONCLUSIONS--We showed that 9 of 18 well-established genetic risk variants were associated with type 2 diabetes in a population-based study. Combining genetic variants has low predictive value for future type 2 diabetes at a population-based level. The genetic polymorphisms only marginally improved the prediction of type 2 diabetes beyond clinical characteristics. Diabetes 57:3122-3128, 2008 [ABSTRACT FROM AUTHOR]

We studied patients with idiopathic Parkinson’s disease (PD) from an isolated population in the Netherlands aiming to map gene(s) involved in PD susceptibility. A total of 109 parkinsonism patients were independently ascertained, of whom 62 presented late-onset, idiopathic PD. Genealogical research showed that 45 index cases with idiopathic PD were linked to a common ancestor, indicating familiar clustering among the patients. This strong familial clustering was highly significant ( P=0.005) when compared to random controls from the same population. We performed a genome wide scan using 382 polymorphic markers in 44 distantly related PD patients plus 112 unaffected first-degree relatives and spouses. Our genome wide association analysis (DISLAMB) revealed evidence of association at a nominal P-value<0.01 for markers D2S2333, D4S405, D9S158, D13S153. Other regions on chromosomes 3p, 4q, 14q, 17p and 17q were found at a significance level of P<0.05. In a follow-up study, we investigated all the positive regions using a denser marker set and a larger sample (total of 630 individuals including all late-onset PD patients). The strongest evidence for association remained for the 9q and 14q region. A significant association was found for marker D9S1838 (OR=2.0, 95% CI 1.1–3.5, P=0.014) and D14S65 (OR=3.2, 95% CI 1.7–6.1, P<0.001). Moreover, a common haplotype with excess of sharing among late-onset PD cases was observed on both regions. Our results suggest the existence of two loci influencing PD susceptibility on chromosome 9q and 14q. [ABSTRACT FROM AUTHOR]

The genetic make-up of genetically isolated populations may differ from a general population as a result of genetic drift and founder effects. We assessed the extent of this deviation in a recently isolated population located in the southwest of the Netherlands and studied as part of the Genetic Research in Isolated Population (GRIP) program. A gene-dropping experiment was performed in a large pedigree from this isolate, assuming different initial frequencies in the population founders came from. Allelic frequencies in the last generations of this pedigree were estimated. Simulation analysis showed large fluctuations, as measured by variation coefficient and sufficient loss probability, when initial frequencies were lower than or equal to 1%. For initial frequencies larger than 1% the fluctuations were small. We also analyzed mean heterozygosity and allele diversity of 592 markers in a random sample from the GRIP population. The results were compared with a general population (CEPH sample), old large isolate (Icelandic sample) and the small-sized population of Talana (Sardinia). GRIP mean heterozygosity and mean number of alleles were significantly lower as compared with CEPH and Iceland, but much higher when compared with the Talana population. We also concluded that the findings from the GRIP population for common variants (>1%) are likely to be extendable to other young isolates inEuropeas well as to outbred populations. [ABSTRACT FROM AUTHOR]

IGFs are important regulators of pancreatic beta-cell development, growth, and maintenance. Mutations in the IGF genes have been found to be associated with type 2 diabetes, myocardial infarction, birth weight, and obesity. These associations could result from changes in insulin secretion. We have analyzed glucose-stimulated insulin secretion using hyperglycemic clamps in carriers of a CA repeat in the IGF-I promoter and an ApaI polymorphism in the IGF-II gene. Normal and impaired glucose-tolerant subjects (n = 237) were independently recruited from three different populations in the Netherlands and Germany to allow independent replication of associations. Both first- and second-phase insulin secretion were not significantly different between the various IGF-I or IGF-II genotypes. Remarkably, noncarriers of the IGF-I CA repeat allele had both a reduced insulin sensitivity index (ISI) and disposition index (DI), suggesting an altered balance between insulin secretion and insulin action. Other diabetes-related parameters were not significantly different for both the IGF-I and IGF-II gene variant. We conclude that gene variants in the IGF-I and IGF-II genes are not associated with detectable variations in glucose-stimulated insulin secretion in these three independent populations. Further studies are needed to examine the exact contributions of the IGF-I CA repeat alleles to variations in ISI and DI. [ABSTRACT FROM AUTHOR]

Multiple genes, interacting with the environment, contribute to the susceptibility to type 2 diabetes. We performed a genome-wide search to localize type 2 diabetes susceptibility genes in a recently genetically isolated population in the Netherlands. We identified 79 nuclear families with type 2 diabetes who were related within 13 generations and performed a 770-marker genome-wide scan search for shared founder alleles. Twenty-six markers yielded a logarithm of odds (LOD) score >0.59 (nominal P < 0.05), of which 7 reached LOD scores >1.17 (nominal P < 0.01). The strongest evidence for a type 2 diabetes locus was at marker D18S63 on chromosome 18p (LOD 2.3, P = 0.0006). This region was investigated further using additional markers. For one of these markers (D18S1105), we found a significant association with type 2 diabetes (odds ratio 6.7 [95% CI 1.5-30.7], P = 0.005 for the 97-bp allele, assuming a dominant model), which increased when limiting the analysis to patients with high BMI (12.25 [2.1-71], P = 0.003). A locus on chromosome 18p in patients with high BMI was suggested earlier by Parker et al. Our study is the first to confirm this locus. [ABSTRACT FROM AUTHOR]

Type 1 diabetes has a substantial genetic component, with consistent evidence for a susceptibility locus in the HLA-DR/DQ region (chromosome 6p) and the insulin gene region (chromosome 11p). Genome scans have identified >18 other genomic regions that may harbor putative type 1 diabetes genes. However, evidence for most regions varies in different data sets. Given the genetic heterogeneity of type 1 diabetes, studies in homogeneous genetically isolated populations may be more successful in mapping susceptibility loci than in complex outbred populations. We describe a genome-wide search in a recently Dutch isolated population. We identified 43 patients that could be traced back to a common ancestor within 15 generations and performed a genome-wide scan using a combined linkage- and association-based approach. In addition to the HLA locus, evidence for type 1 diabetes loci was observed on chromosome 8q24 (marker D8S1128) and on chromosome 17q24 (marker D17S2059). Both the 8q and 17q localization are supported by allele-sharing at adjacent markers in affected individuals. Statistical evidence for a conserved ancestral haplotype was found for chromosome 8q24. [ABSTRACT FROM AUTHOR]

Creutzfeldt-Jakob disease (CJD) can be transmitted through human growth hormone or gonadotrophin administration, dura mater or cornea transplantation, depth EEG monitoring and the use of contaminated neurosurgical instruments. We describe the first two dura mater associated CJD cases in the Netherlands. Ten and fourteen years before the onset of symptoms both patients received a Lyodura implantation. Findings are discussed in light of the growing epidemic of CJD among dura mater recipients. [ABSTRACT FROM AUTHOR]

Summary: The Rotterdam Study is a prospective cohort study that has been ongoing since 1990 in the city of Rotterdam, the Netherlands, among 7983 people aged 55 years or older. One part of the study targets neurological diseases, others deal with cardiovascular, ophthalmological, and endocrine diseases. The findings of the Rotterdam Study have been presented in some 500 research articles and reports. Here we give the reasons for the study and its design, and present a summary of what has been learned about the frequencies and causes of neurological diseases. Perhaps the most important message from the Rotterdam Study is the great potential for prevention or postponement of neurological diseases in elderly people. The time for preventive nihilism is over. [Copyright &y& Elsevier]

Background: Alzheimer's disease is one of the most heritable diseases in elderly people and the most common type of dementia. In addition to the major genetic determinant of Alzheimer's disease, the APOE gene, 23 genetic variants have been associated with the disease. We assessed the effects of these variants and APOE on cumulative risk and age at onset of Alzheimer's disease and all-cause dementia.Methods: We studied incident dementia in cognitively healthy participants (aged >45 years) from the community-based Rotterdam Study, an ongoing prospective cohort study based in Rotterdam, the Netherlands, focusing on neurological, cardiovascular, endocrine, and ophthalmological disorders, and other diseases in elderly people. The Rotterdam Study comprises participants in three baseline cohorts (initiated in 1990, 2000, and 2006), who are re-invited to the research centre every 3-4 years, and continuously monitored by records from general practitioners and medical specialists. Cumulative incidence curves up to age 100 years were calculated for Alzheimer's disease and dementia, taking into account mortality as a competing event. These risk curves were stratified by APOE genotypes, tertiles of a weighted genetic risk score (GRS) of 23 Alzheimer's disease-associated genetic variants, and parental history of dementia.Findings: 12 255 of 14 926 participants (58·5% women) from the Rotterdam Study were included in this study. During a median follow-up of 11·0 years (IQR 4·9-15·9; 133 123 person years), 1609 participants developed dementia, of whom 1262 (78%) were classified as having Alzheimer's disease; 3310 people died of causes other than dementia. Both APOE and the GRS significantly modified the risks of Alzheimer's disease and dementia. There was evidence for a significant interaction between APOE genotypes and the GRS for the association with Alzheimer's disease (p=0·03) and dementia (p=0·04); the risk for carriers homozygous for APOE ε4 was modified most by the GRS. In carriers homozygous for APOE ε4, the difference between the high-risk tertile and the low-risk tertile by age 85 years was 27·0% for Alzheimer's disease (p=8·5 × 10-3) and 37·2% for dementia (p=2·2 × 10-4), which translates to a 7-10 year difference in age at onset. Comparing the risk extremes, which were carriers homozygous for APOE ε2 or heterozygous with one copy each of the ε2 and ε3 alleles in the low-risk tertile of the GRS versus carriers homozygous for APOE ε4 in the high-risk tertile of the GRS, the difference in risk by age 85 years was 58·6% (4·1% vs 62·7%; p=6·2 × 10-13) for Alzheimer's disease, and 70·3% (7·2% vs 77·5%; p=3·0 × 10-23) for dementia. These risk differences translate into an 18-29 years difference in age at onset for Alzheimer's disease and an 18-23 year difference in age at onset dementia. This difference becomes more pronounced when parental history of dementia is considered (difference in risk 83·8%; p=1·1 × 10-20).Interpretation: Common variants with small individual effects jointly modify the risk and age at onset of Alzheimer's disease and dementia, particularly in APOE ε4 carriers. These findings highlight the potential of common variants in determining Alzheimer's disease risk.Funding: None. [ABSTRACT FROM AUTHOR]

Introduction: We investigated whether a risk score based on genetic risk variants for Parkinson's disease (PD) is associated with the risk and improves prediction of incident PD, and whether the risk score is associated with basic activities of daily living (BADL) in healthy individuals.Methods: Within the population-based Rotterdam Study, we genotyped 26 independent risk variants for PD and constructed a genetic risk score in 7167 participants who were free of parkinsonism and dementia at baseline (1990 or 2000). Participants were followed for a maximum of twenty years for the onset of parkinsonism, dementia or death until January 1, 2011 (median follow-up 12.1 years). We studied the relationship between the genetic risk score and incident PD with adjustment for age, sex, smoking and parental history. In an independent sample of 2997 persons free of parkinsonism and dementia, we studied whether the PD risk score was associated with impaired BADL.Results: During follow-up (median 12.1 years), 99 persons were diagnosed with incident PD. The genetic risk score was associated with incident PD (hazard ratio per standard deviation risk 1.25 [95% confidence interval = 1.02; 1.55]), but did not substantially improve prediction (change in C-statistic 0.687 [0.628; 0.745] to 0.698 [0.635; 0.760], ΔC = 0.011 [-0.011; 0.033]). The genetic risk score was associated with a higher probability of any impairment in BADL (odds ratio = 1.11 [1.00; 1.23]).Conclusion: Genetic variants for PD are associated with the risk of incident PD in the general population and with impairment in daily functioning in individuals without clinical parkinsonism, but do not improve the clinical prediction of PD. However, we were probably underpowered to detect a small improvement in PD prediction. [ABSTRACT FROM AUTHOR]

We obtained conclusive linkage of Alzheimer disease (AD) with a candidate region of 19.7 cM at 7q36 in an extended multiplex family, family 1270, ascertained in a population-based study of early-onset AD in the northern Netherlands. Single-nucleotide polymorphism and haplotype association analyses of a Dutch patient-control sample further supported the linkage at 7q36. In addition, we identified a shared haplotype at 7q36 between family 1270 and three of six multiplex AD-affected families from the same geographical region, which is indicative of a founder effect and defines a priority region of 9.3 cM. Mutation analysis of coding exons of 29 candidate genes identified one linked synonymous mutation, g.38030G→C in exon 10, that affected codon 626 of the PAX transactivation domain interacting protein gene (PAXIP1). It remains to be determined whether PAXIP1 has a functional role in the expression of AD in family 1270 or whether another mutation at this locus explains the observed linkage and sharing. Together, our linkage data from the informative family 1270 and the association data in the population- based early-onset AD patient-control sample strongly support the identification of a novel AD locus at 7q36 and re-emphasize the genetic heterogeneity of AD. [ABSTRACT FROM AUTHOR]

Prion diseases are being monitored in The Netherlands since 29 years, the national registry is coordinated by Erasmus Medical Center. Since 2010, yearly on average 31 new patients are diagnosed with prion disease. There is a slight increase in incidence of prion diseases, probably due to better recognition and improved diagnostics. The most recent development in the diagnostic is the real-time quaking-induced conversion (RT-QuIC) test, which can detect prion proteins in cerebrospinal fluid with high sensitivity and specificity. The polymorphism of codon 129 of the prion gene (PRNP) determines the susceptibility for the different subtypes of Creutzfeldt-Jakob disease (CJD) and influences the clinical course. Awareness for atypical presentations of CJD and for CJD mimics is important, such as autoimmune encephalitis, which is often treatable and can resemble CJD.

Background: Brain-derived neurotropic factor (BDNF) plays a vital role in neuronal survival and plasticity and facilitates long-term potentiation, essential for memory. Alterations in BDNF signaling have been associated with cognitive impairment, dementia, and Alzheimer's disease. Although peripheral BDNF levels are reduced in dementia patients, it is unclear whether changes in BDNF levels precede or follow dementia onset., Objective: In the present study, we examined the association between BDNF plasma levels and dementia risk over a follow-up period of up to 16 years., Methods: Plasma BDNF levels were assessed in 758 participants of the Rotterdam Study. Dementia was assessed from baseline (1997-1999) to follow-up until January 2016. Associations of plasma BDNF and incident dementia were assessed with Cox proportional hazards models, adjusted for age and sex. Associations between plasma BDNF and lifestyle and metabolic factors are investigated using linear regression., Results: During a follow up of 3,286 person-years, 131 participants developed dementia, of whom 104 had Alzheimer's disease. We did not find an association between plasma BDNF and risk of dementia (adjusted hazard ratio 0.99; 95%CI 0.84-1.16). BDNF levels were positively associated with age (B = 0.003, SD = 0.001, p = 0.002), smoking (B = 0.08, SE = 0.01, p = < 0.001), and female sex (B = 0.03, SE = 0.01, p = 0.03), but not with physical activity level (B = -0.01, SE = 0.01, p = 0.06)., Conclusion: The findings suggest that peripheral BDNF levels are not associated with an increased risk of dementia.

Background: The blood metabolome incorporates cues from the environment and the host's genetic background, potentially offering a holistic view of an individual's health status., Methods: We have compiled a vast resource of proton nuclear magnetic resonance metabolomics and phenotypic data encompassing over 25 000 samples derived from 26 community and hospital-based cohorts., Results: Using this resource, we constructed a metabolomics-based age predictor (metaboAge) to calculate an individual's biological age. Exploration in independent cohorts demonstrates that being judged older by one's metabolome, as compared with one's chronological age, confers an increased risk on future cardiovascular disease, mortality, and functionality in older individuals. A web-based tool for calculating metaboAge (metaboage.researchlumc.nl) allows easy incorporation in other epidemiological studies. Access to data can be requested at bbmri.nl/samples-images-data., Conclusions: In summary, we present a vast resource of metabolomics data and illustrate its merit by constructing a metabolomics-based score for biological age that captures aspects of current and future cardiometabolic health.

Background: Chronic obstructive pulmonary disease (COPD) is a common lung disorder characterized by persistent and progressive airflow limitation as well as systemic changes. Metabolic changes in blood may help detect COPD in an earlier stage and predict prognosis., Methods: We conducted a comprehensive study of circulating metabolites, measured by proton Nuclear Magnetic Resonance Spectroscopy, in relation with COPD and lung function. The discovery sample consisted of 5557 individuals from two large population-based studies in the Netherlands, the Rotterdam Study and the Erasmus Rucphen Family study. Significant findings were replicated in 12,205 individuals from the Lifelines-DEEP study, FINRISK and the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) studies. For replicated metabolites further investigation of causality was performed, utilizing genetics in the Mendelian randomization approach., Results: There were 602 cases of COPD and 4955 controls used in the discovery meta-analysis. Our logistic regression results showed that higher levels of plasma Glycoprotein acetyls (GlycA) are significantly associated with COPD (OR = 1.16, P = 5.6 × 10 - 4 in the discovery and OR = 1.30, P = 1.8 × 10 - 6 in the replication sample). A bi-directional two-sample Mendelian randomization analysis suggested that circulating blood GlycA is not causally related to COPD, but that COPD causally increases GlycA levels. Using the prospective data of the same sample of Rotterdam Study in Cox-regression, we show that the circulating GlycA level is a predictive biomarker of COPD incidence (HR = 1.99, 95%CI 1.52-2.60, comparing those in the highest and lowest quartile of GlycA) but is not significantly associated with mortality in COPD patients (HR = 1.07, 95%CI 0.94-1.20)., Conclusions: Our study shows that circulating blood GlycA is a biomarker of early COPD pathology.

Gut microbiota has been implicated in major diseases affecting the human population and has also been linked to triglycerides and high-density lipoprotein levels in the circulation. Recent development in metabolomics allows classifying the lipoprotein particles into more details. Here, we examine the impact of gut microbiota on circulating metabolites measured by Nuclear Magnetic Resonance technology in 2309 individuals from the Rotterdam Study and the LifeLines-DEEP cohort. We assess the relationship between gut microbiota and metabolites by linear regression analysis while adjusting for age, sex, body-mass index, technical covariates, medication use, and multiple testing. We report an association of 32 microbial families and genera with very-low-density and high-density subfractions, serum lipid measures, glycolysis-related metabolites, ketone bodies, amino acids, and acute-phase reaction markers. These observations provide insights into the role of microbiota in host metabolism and support the potential of gut microbiota as a target for therapeutic and preventive interventions.

Background: Multiple sclerosis (MS) is a complex disease resulting from the joint effect of many genes. It has been speculated that rare variants might explain part of the missing heritability of MS., Objective: To identify rare coding genetic variants by analyzing a large MS pedigree with 11 affected individuals in several generations., Methods: Genome-wide linkage screen and whole exome sequencing (WES) were performed to identify novel coding variants in the shared region(s) and in the known 110 MS risk loci. The candidate variants were then assessed in 591 MS patients and 3169 controls., Results: Suggestive evidence for linkage was obtained to 7q11.22-q11.23. In WES data, a rare missense variant p.R183C in FKBP6 was identified that segregated with the disease in this family. The minor allele frequency was higher in an independent cohort of MS patients than in healthy controls (1.27% vs 0.95%), but not significant (odds ratio (OR) = 1.33 (95% confidence interval (CI): 0.8-2.4), p = 0.31)., Conclusion: The rare missense variant in FKBP6 was identified in a large Dutch MS family segregating with the disease. This association to MS was not found in an independent MS cohort. Overall, genome-wide studies in larger cohorts are needed to adequately investigate the role of rare variants in MS risk.

Genome-wide association studies (GWAS) of quantitative electrocardiographic (ECG) traits in large consortia have identified more than 130 loci associated with QT interval, QRS duration, PR interval, and heart rate (RR interval). In the current study, we meta-analyzed genome-wide association results from 30,000 mostly Dutch samples on four ECG traits: PR interval, QRS duration, QT interval, and RR interval. SNP genotype data was imputed using the Genome of the Netherlands reference panel encompassing 19 million SNPs, including millions of rare SNPs (minor allele frequency < 5%). In addition to many known loci, we identified seven novel locus-trait associations: KCND3, NR3C1, and PLN for PR interval, KCNE1, SGIP1, and NFKB1 for QT interval, and ATP2A2 for QRS duration, of which six were successfully replicated. At these seven loci, we performed conditional analyses and annotated significant SNPs (in exons and regulatory regions), demonstrating involvement of cardiac-related pathways and regulation of nearby genes.

Next-generation sequencing has contributed to our understanding of the genetics of Alzheimer's disease (AD) and has explained a substantial part of the missing heritability of familial AD. We sequenced 19 exomes from 8 Dutch families with a high AD burden and identified EIF2AK3, encoding for protein kinase RNA-like endoplasmic reticulum kinase (PERK), as a candidate gene. Gene-based burden analysis in a Dutch AD exome cohort containing 547 cases and 1070 controls showed a significant association of EIF2AK3 with AD (OR 1.84 [95% CI 1.07-3.17], p-value 0.03), mainly driven by the variant p.R240H. Genotyping of this variant in an additional cohort from the Rotterdam Study showed a trend toward association with AD (p-value 0.1). Immunohistochemical staining with pPERK and peIF2α of 3 EIF2AK3 AD carriers showed an increase in hippocampal neuronal cells expressing these proteins compared with nondemented controls, but no difference was observed in AD noncarriers. This study suggests that rare variants in EIF2AK3 may be associated with disease risk in AD., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Exploring the role of Alzheimer's disease (AD) implicated pathways in the predementia phase may provide new insight for preventive and clinical trials targeting disease specific pathways., Methods: We constructed weighted Genetic risk scores, first based on 20 genome-wide significant AD risk variants and second clustering these variants within pathways. Risk scores were investigated for their association with AD, mild cognitive impairment, and brain magnetic resonance imaging phenotypes including white matter lesions, hippocampal volume, and brain volume., Results: The risk score capturing endocytosis pathway was significantly associated with mild cognitive impairment (P = 1.44 × 10 -4 ). Immune response (P = .016) and clathrin/AP2 adaptor complex pathway (P = 3.55 × 10 -3 ) excluding apolipoprotein E also showed modest association with white matter lesions but did not sustain Bonferroni correction (P = 9.09 × 10 -4 )., Discussion: Our study suggests that the clinical spectrum of early AD pathology is explained by different biological pathways, in particular, the endocytosis, clathrin/AP2 adaptor complex, and immune response pathways, that are independent of apolipoprotein E (APOE)., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: Occupational pesticide exposure is associated with a wide range of diseases, including lung diseases, but it is largely unknown how pesticides influence airway disease pathogenesis. A potential mechanism might be through epigenetic mechanisms, like DNA methylation. Therefore, we assessed associations between occupational exposure to pesticides and genome-wide DNA methylation sites., Methods: 1561 subjects of LifeLines were included with either no (n=1392), low (n=108) or high (n=61) exposure to any type of pesticides (estimated based on current or last held job). Blood DNA methylation levels were measured using Illumina 450K arrays. Associations between pesticide exposure and 420 938 methylation sites (CpGs) were assessed using robust linear regression adjusted for appropriate confounders. In addition, we performed genome-wide stratified and interaction analyses by gender, smoking and airway obstruction status, and assessed associations between gene expression and methylation for genome-wide significant CpGs (n=2802)., Results: In total for all analyses, high pesticide exposure was genome-wide significantly (false discovery rate P<0.05) associated with differential DNA methylation of 31 CpGs annotated to 29 genes. Twenty of these CpGs were found in subjects with airway obstruction. Several of the identified genes, for example, RYR1 , ALLC , PTPRN2 , LRRC3B , PAX2 and VTRNA2-1 , are genes previously linked to either pesticide exposure or lung-related diseases. Seven out of 31 CpGs were associated with gene expression levels., Conclusions: We show for the first time that occupational exposure to pesticides is genome-wide associated with differential DNA methylation. Further research should reveal whether this differential methylation plays a role in the airway disease pathogenesis induced by pesticides., Competing Interests: Competing interests: DSP reports: The University of Groningen has received money for Professor Postma regarding a grant for research from Astra Zeneca, Chiesi, Genentec, GSK and Roche. Fees for consultancies were given to the University of Groningen by Astra Zeneca, Boehringer Ingelheim, Chiesi, GSK, Takeda and TEVA. All other authors declare they have no actual or potential competing financial interest., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Valosin-containing protein (VCP) is involved in multiple cellular activities. Mutations in VCP lead to heterogeneous clinical presentations including inclusion body myopathy with Paget's disease of the bone, frontotemporal dementia and amyotrophic lateral sclerosis, even in patients carrying the same mutation. We screened a cohort of 48 patients with familial frontotemporal dementia (FTD) negative for MAPT, GRN, and C9orf72 mutations for other known FTD genes by using whole exome sequencing. In addition, we carried out targeted sequencing of a cohort of 37 patients with frontotemporal lobar degeneration with Transactive response DNA-binding protein 43 (TDP-43) subtype from the Netherlands Brain bank. Two novel (p.Thr262Ser and p.Arg159Ser) and one reported (p.Met158Val) VCP mutations in three patients with a clinical diagnosis of FTD were identified, and were absence in population-match controls. All three patients presented with behavioral changes, with additional semantic deficits in one. No signs of Paget or muscle disease were observed. Pathological examination of the patient with VCP p.Arg159Ser mutation showed numerous TDP-43 immunoreactive (IR) neuronal intranuclear inclusions (NII) and dystrophic neurites (DN), while a lower number of NII and DN were observed in the patient with the VCP p.Thr262Ser mutation. Pathological findings of both patients were consistent with FTLD-TDP subtype D. Furthermore, only rare VCP-IR NII was observed in both cases. Our study expands the clinical heterogeneity of VCP mutations carriers, and indicates that other additional factors, such as genetic modifiers, may determine the clinical phenotype.

Background: Despite high heritability, little success was achieved in mapping genetic determinants of depression-related traits by means of genome-wide association studies., Methods: To identify genes associated with depressive symptomology, we performed a gene-based association analysis of nonsynonymous variation captured using exome-sequencing and exome-chip genotyping in a genetically isolated population from the Netherlands (n = 1999). Finally, we reproduced our significant findings in an independent population-based cohort (n = 1604)., Results: We detected significant association of depressive symptoms with a gene NKPD1 (p = 3.7 × 10 -08 ). Nonsynonymous variants in the gene explained 0.9% of sex- and age-adjusted variance of depressive symptoms in the discovery study, which is translated into 3.8% of the total estimated heritability (h 2 = 0.24). Significant association of depressive symptoms with NKPD1 was also observed (n = 1604; p = 1.5 × 10 -03 ) in the independent replication sample despite little overlap with the discovery cohort in the set of nonsynonymous genetic variants observed in the NKPD1 gene. Meta-analysis of the discovery and replication studies improved the association signal (p = 1.0 × 10 -09 )., Conclusions: Our study suggests that nonsynonymous variation in the gene NKPD1 affects depressive symptoms in the general population. NKPD1 is predicted to be involved in the de novo synthesis of sphingolipids, which have been implicated in the pathogenesis of depression., (Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Although previous studies have documented a bottleneck in the transmission of mtDNA genomes from mothers to offspring, several aspects remain unclear, including the size and nature of the bottleneck. Here, we analyze the dynamics of mtDNA heteroplasmy transmission in the Genomes of the Netherlands (GoNL) data, which consists of complete mtDNA genome sequences from 228 trios, eight dizygotic (DZ) twin quartets, and 10 monozygotic (MZ) twin quartets. Using a minor allele frequency (MAF) threshold of 2%, we identified 189 heteroplasmies in the trio mothers, of which 59% were transmitted to offspring, and 159 heteroplasmies in the trio offspring, of which 70% were inherited from the mothers. MZ twin pairs exhibited greater similarity in MAF at heteroplasmic sites than DZ twin pairs, suggesting that the heteroplasmy MAF in the oocyte is the major determinant of the heteroplasmy MAF in the offspring. We used a likelihood method to estimate the effective number of mtDNA genomes transmitted to offspring under different bottleneck models; a variable bottleneck size model provided the best fit to the data, with an estimated mean of nine individual mtDNA genomes transmitted. We also found evidence for negative selection during transmission against novel heteroplasmies (in which the minor allele has never been observed in polymorphism data). These novel heteroplasmies are enhanced for tRNA and rRNA genes, and mutations associated with mtDNA diseases frequently occur in these genes. Our results thus suggest that the female germ line is able to recognize and select against deleterious heteroplasmies., (© 2016 Li et al.; Published by Cold Spring Harbor Laboratory Press.)

Background and Purpose: Genome-wide association studies have identified single-nucleotide polymorphisms (SNPs) for intracranial aneurysms in clinical samples. In addition, SNPs have been discovered for blood pressure, one of the strongest risk factors for intracranial aneurysms. We studied the role of these genetic variants on occurrence and size of unruptured intracranial aneurysms, discovered incidentally in a general community-dwelling population., Methods: In 4890 asymptomatic participants from the Rotterdam Study, 120 intracranial aneurysms were identified on brain imaging and segmented for maximum diameter and volume. Genetic risk scores (GRS) were calculated for intracranial aneurysms (10 SNPs), systolic blood pressure (33 SNPs), and diastolic blood pressure (41 SNPs)., Results: The GRS for intracranial aneurysms was not statistically significantly associated with presence of aneurysms in this population (OR, 1.16; 95% CI, 0.96-1.40; P=0.119), but showed a significant association with both maximum diameter (difference in log-transformed mm per SD increase of GRS, 0.10; 95% CI, 0.02-0.19; P=0.018) and volume (difference in log-transformed µL per SD increase of GRS, 0.21; 95% CI, 0.01-0.41; P=0.040) of aneurysms. GRSs for blood pressures were associated with neither presence nor size of aneurysms., Conclusions: Genetic variants previously identified for intracranial aneurysms in clinical studies relate to the size rather than the presence of incidentally discovered, unruptured intracranial aneurysms in the general population., (© 2015 American Heart Association, Inc.)

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, otolaryngological, locomotor, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over 1200 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

Background: Recent evidence suggests that the type I 3β-hydroxysteroid dehydrogenase, a steroidogenic enzyme encoded by the HSD3B1 gene, could be involved in aldosterone production and that genetic variation in HSD3B1 is associated with blood pressure. These findings challenge the long-standing hypothesis that all adrenocortical steroidogenesis is executed by the type II iso-enzyme, encoded by HSD3B2., Methods: To verify these findings, the adrenal presence of HSD3B1 and its effect on aldosterone synthesis and blood pressure were studied in expression and genetic association analyses, respectively. Expression of HSD3B1 and HSD3B2 was investigated in various adrenocortical tissues (n = 15) and in primary adrenal cell cultures (n = 5) after stimulation with adrenocorticotropin and angiotensin II. Six tagging single nucleotide polymorphisms within the HSD3B1 gene were studied for association with blood pressure and hypertension in a meta-analysis of 4 Dutch cohorts (n = 11,192)., Results: HSD3B1 expression was minimal or absent in adrenocortical tissues, including 6 aldosterone-producing adenomas. In contrast with the ubiquitously expressed HSD3B2 mRNA, HSD3B1 levels were not stimulated by adrenocorticotropin or angiotensin II. No variants in the HSD3B1 gene were associated with blood pressure or the occurrence of hypertension., Conclusions: We found no evidence to support confirmation that HSD3B1 is involved in aldosterone synthesis in the human adrenal cortex or that genetic variation in HSD3B1 affects blood pressure or hypertension, favoring the hypothesis that all adrenocortical steroidogenesis is primarily dependent on the type II 3β-hydroxysteroid dehydrogenase., (© American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Purpose: Genetic testing may be the next step in clinical medicine for a more personalized approach in determining risk of disease. Direct-to-consumer (DTC) personal genome tests may fulfill this role. We explored the practicability and predictive value of DTC tests from four companies (23andMe, deCODEme, Easy DNA, Genetic Testing Laboratories) for AMD., Methods: Body specimens of three individuals were collected and sent to four companies for DNA genotyping and disease risk estimation. In addition, DNA was also genotyped using Illumina HumanOmniExpress 12v1 array in the Rotterdam Study laboratory, and risk estimates of AMD were calculated using the validated prediction model from the population-based Three Continent AMD Consortium., Results: Genotyped results of the four DTC tests matched genotyping performed by the Rotterdam Study laboratory. The estimated risks provided by the companies varied considerably in the tested individuals, from a 1.6-fold difference for overall relative risk to an up to 12-fold difference for lifetime risk. The lifetime risks for the individuals ranged from 1.4% to 16.1% in the DTC tests, while they varied from 0.5% to 4.2% in the validated prediction model. Most important reasons for the differences in risks were the testing of only a limited set of genetic markers, the choice of the reference population, and the methodology applied for risk calculation., Conclusions: Direct-to-consumer personal genome tests are not suitable for clinical application as yet. More comprehensive genetic testing and inclusion of environmental risk factors may improve risk prediction of AMD., (Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.)

Background: Metabolomics, defined as the comprehensive identification and quantification of low-molecular-weight metabolites to be found in a biological sample, has been put forward as a potential tool for classifying individuals according to their risk of coronary heart disease (CHD). Here, we investigated whether a single-point blood measurement of the metabolome is associated with and predictive for the risk of CHD., Methods and Results: We obtained proton nuclear magnetic resonance spectra in 79 cases who developed CHD during follow-up (median 8.1 years) and in 565 randomly selected individuals. In these spectra, 100 signals representing 36 metabolites were identified. Applying least absolute shrinkage and selection operator regression, we defined a weighted metabolite score consisting of 13 proton nuclear magnetic resonance signals that optimally predicted CHD. This metabolite score, including signals representing a lipid fraction, glucose, valine, ornithine, glutamate, creatinine, glycoproteins, citrate, and 1.5-anhydrosorbitol, was associated with the incidence of CHD independent of traditional risk factors (TRFs) (hazard ratio 1.50, 95% CI 1.12-2.01). Predictive performance of this metabolite score on its own was moderate (C-index 0.75, 95% CI 0.70-0.80), but after adding age and sex, the C-index was only modestly lower than that of TRFs (C-index 0.81, 95% CI 0.77-0.85 and C-index 0.82, 95% CI 0.78-0.87, respectively). The metabolite score was also associated with prevalent CHD independent of TRFs (odds ratio 1.59, 95% CI 1.19-2.13)., Conclusion: A metabolite score derived from a single-point metabolome measurement is associated with CHD, and metabolomics may be a promising tool for refining and improving the prediction of CHD., (Copyright © 2014 Mosby, Inc. All rights reserved.)

Objective: To examine effect modification between genetic susceptibility to age-related macular degeneration (AMD) and dietary antioxidant or fish consumption on AMD risk., Design: Pooled data analysis of population-based cohorts., Participants: Participants from the Blue Mountains Eye Study (BMES) and Rotterdam Study (RS)., Methods: Dietary intakes of antioxidants (lutein/zeaxanthin [LZ], β-carotene, and vitamin C), long-chain omega-3 polyunsaturated fatty acids, and zinc were estimated from food frequency questionnaires. The AMD genetic risk was classified according to the number of risk alleles of CFH (rs1061170) or ARMS2 (rs10490924) as low (no or 1 risk allele) or high (≥ 2 risk alleles). Interactions between dietary intake and genetic risk levels were assessed. Associations between dietary intake and AMD risk were assessed comparing the highest with the 2 lower intake tertiles by genetic risk subgroups using discrete logistic regression, conducted in each study separately and then using pooled data. Participants without AMD lesions at any visit were controls. We adjusted for age and sex in analyses of each cohort sample and for smoking status and study site in pooled-data analyses., Main Outcome Measures: All 15-year incident late AMD cases were confirmed by chief investigators of the Beaver Dam Eye Study, BMES, and RS. Intergrader reproducibility was assessed in an early AMD subsample, with 86.4% agreement between BMES and RS graders, allowing for a 1-step difference on a 5-step AMD severity scale., Results: In pooled data analyses, we found significant interaction between AMD genetic risk status and LZ intake (P=0.0009) but nonsignificant interactions between genetic risk status and weekly fish consumption (P=0.05) for risk of any AMD. Among participants with high genetic risk, the highest intake tertile of LZ was associated with a >20% reduced risk of early AMD, and weekly consumption of fish was associated with a 40% reduced risk of late AMD. No similar association was evident among participants with low genetic risk. No interaction was detected between β-carotene or vitamin C and genetic risk status., Conclusions: Protection against AMD from greater LZ and fish consumption in persons with high genetic risk based on 2 major AMD genes raises the possibility of personalized preventive interventions., (Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Within the Netherlands a national network of biobanks has been established (Biobanking and Biomolecular Research Infrastructure-Netherlands (BBMRI-NL)) as a national node of the European BBMRI. One of the aims of BBMRI-NL is to enrich biobanks with different types of molecular and phenotype data. Here, we describe the Genome of the Netherlands (GoNL), one of the projects within BBMRI-NL. GoNL is a whole-genome-sequencing project in a representative sample consisting of 250 trio-families from all provinces in the Netherlands, which aims to characterize DNA sequence variation in the Dutch population. The parent-offspring trios include adult individuals ranging in age from 19 to 87 years (mean=53 years; SD=16 years) from birth cohorts 1910-1994. Sequencing was done on blood-derived DNA from uncultured cells and accomplished coverage was 14-15x. The family-based design represents a unique resource to assess the frequency of regional variants, accurately reconstruct haplotypes by family-based phasing, characterize short indels and complex structural variants, and establish the rate of de novo mutational events. GoNL will also serve as a reference panel for imputation in the available genome-wide association studies in Dutch and other cohorts to refine association signals and uncover population-specific variants. GoNL will create a catalog of human genetic variation in this sample that is uniquely characterized with respect to micro-geographic location and a wide range of phenotypes. The resource will be made available to the research and medical community to guide the interpretation of sequencing projects. The present paper summarizes the global characteristics of the project.

Objective: To investigate whether 57 genetic risk loci recently identified in a large-scale genome-wide association study in adult patients with multiple sclerosis (MS) are also associated with a risk for pediatric-onset MS and whether they can predict MS diagnosis in children presenting with acquired demyelinating syndromes (ADS)., Methods: We included 188 children with ADS, of whom 53 were diagnosed with MS, 466 patients with adult-onset MS, and 2,046 adult controls in our cohort study. Weighted genetic risk scores (wGRS) were calculated to evaluate genetic effects., Results: Mean wGRS was significantly higher for patients with pediatric-onset MS (7.32 ± 0.53) as compared with patients with monophasic ADS (7.10 ± 0.47, p = 0.01) and controls (7.11 ± 0.53, p < 0.01). We found no difference in mean wGRS of participants with monophasic ADS (7.10 ± 0.47) and controls (7.11 ± 0.53). The ability of the wGRS for the 57 single nucleotide polymorphisms (SNPs) to discriminate between children with MS and those with monophasic ADS was moderate (area under the curve [AUC] = 0.64), but improved with the addition of sex and HLA-DRB1*15 (AUC = 0.70). The combined effect of 57 SNPs exceeded the effect of HLA-DRB1*15 alone in our risk models for pediatric- and adult-onset MS., Conclusion: The previously reported 57 SNPs for adult-onset MS also confer increased susceptibility to pediatric-onset MS, but not to monophasic ADS.

Purpose: Prediction models for age-related macular degeneration (AMD) based on case-control studies have a tendency to overestimate risks. The aim of this study is to develop a prediction model for late AMD based on data from population-based studies., Design: Three population-based studies: the Rotterdam Study (RS), the Beaver Dam Eye Study (BDES), and the Blue Mountains Eye Study (BMES) from the Three Continent AMD Consortium (3CC)., Participants: People (n = 10,106) with gradable fundus photographs, genotype data, and follow-up data without late AMD at baseline., Methods: Features of AMD were graded on fundus photographs using the 3CC AMD severity scale. Associations with known genetic and environmental AMD risk factors were tested using Cox proportional hazard analysis. In the RS, the prediction of AMD was estimated for multivariate models by area under receiver operating characteristic curves (AUCs). The best model was validated in the BDES and BMES, and associations of variables were re-estimated in the pooled data set. Beta coefficients were used to construct a risk score, and risk of incident late AMD was calculated using Cox proportional hazard analysis. Cumulative incident risks were estimated using Kaplan-Meier product-limit analysis., Main Outcome Measures: Incident late AMD determined per visit during a median follow-up period of 11.1 years with a total of 4 to 5 visits., Results: Overall, 363 participants developed incident late AMD, 3378 participants developed early AMD, and 6365 participants remained free of any AMD. The highest AUC was achieved with a model including age, sex, 26 single nucleotide polymorphisms in AMD risk genes, smoking, body mass index, and baseline AMD phenotype. The AUC of this model was 0.88 in the RS, 0.85 in the BDES and BMES at validation, and 0.87 in the pooled analysis. Individuals with low-risk scores had a hazard ratio (HR) of 0.02 (95% confidence interval [CI], 0.01-0.04) to develop late AMD, and individuals with high-risk scores had an HR of 22.0 (95% CI, 15.2-31.8). Cumulative risk of incident late AMD ranged from virtually 0 to more than 65% for those with the highest risk scores., Conclusions: Our prediction model is robust and distinguishes well between those who will develop late AMD and those who will not. Estimated risks were lower in these population-based studies than in previous case-control studies., (Copyright © 2013. Published by Elsevier Inc.)

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

Objective: Circulating levels of total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol, and triglycerides are recognized risk factors for cardiovascular disease. We tested the hypothesis that the cumulative effects of common genetic variants for lipids are collectively associated with subclinical atherosclerosis and incident coronary heart disease., Approach and Results: Participants were drawn from the Erasmus Rucphen Family Study (n=2269) and the Rotterdam Study (n=8130). Linear regression and Cox proportional hazards models were applied to assess the influence of 4 risk scores derived from common genetic variants for lipids (total cholesterol, LDL-C, high-density lipoprotein cholesterol, and triglycerides) on carotid plaque, intima-media thickness, incident myocardial infarction, and coronary heart disease. Adjusted for age and sex, all 4 risk scores were associated with carotid plaque. This relationship was the strongest for the LDL-C score, which increased plaque score by 0.102 per SD increase in genetic risk score (P=3.2 × 10(-8)). The LDL-C score was also nominally associated with intima-media thickness, which increased 0.006 mm per SD increase in score (P=0.05). Both the total cholesterol and LDL-C scores were associated with incident myocardial infarction and coronary heart disease with hazard ratios between 1.10 and 1.13 per SD increase in score. Inclusion of additional risk factors as covariates minimally affected these results., Conclusions: Common genetic variants with small effects on lipid levels are, in combination, significantly associated with subclinical and clinical cardiovascular outcomes. As knowledge of genetic variation increases, preclinical genetic screening tools might enhance the prediction and prevention of clinical events.

The central nervous system has the second highest concentration of lipids after adipose tissue. Alterations in neural membrane phospho- and sphingolipid composition can influence crucial intra- and intercellular signalling and alter the membrane's properties. Recently, the polyunsaturated fatty acids (PUFA) hypothesis for depression suggests that phospho- and sphingolipid metabolism includes potential pathways for the disease. In 742 people from a Dutch family-based study, we assessed the relationships between 148 different plasma phospho- and sphingolipid species and depression/anxiety symptoms as measured by the Hospital Anxiety and Depression Scales (HADS-A and HADS-D) and the Centre for Epidemiological Studies Depression Scale (CES-D). We observed significant differences in plasma sphingomyelins (SPM), particularly the SPM 23:1/SPM 16:0 ratio, which was inversely correlated with depressive symptom scores. We observed a similar trend for plasma phosphatidylcholines (PC), particularly the molar proportion of PC O 36:4 and its ratio to ceramide CER 20:0. Absolute levels of PC O 36:4 were also associated with depression symptoms in an independent replication. To our knowledge this is the first study on depressive symptoms that focuses on specific phospho- and sphingolipid molecules in plasma rather than total PUFA concentrations. The findings of this lipidomic study suggests that plasma sphingomyelins and ether phospholipids should be further studied for their potential as biomarkers and for a better understanding of the underlying mechanisms of this systemic disease., (Copyright © 2012. Published by Elsevier Ltd.)

Plasma concentrations of Aβ40 and Aβ42 rise with age and are increased in people with mutations that cause early-onset Alzheimer's disease (AD). Amyloid beta (Aβ) plasma levels were successfully used as an (endo)phenotype for gene discovery using a linkage approach in families with dominant forms of disease. Here, we searched for loci involved in Aβ plasma levels in a series of non-demented patients with hypertension in the Erasmus Rucphen Family study. Aβ40 and Aβ42 levels were determined in 125 subjects with severe hypertension. All patients were genotyped with a 6,000 single nucleotide polymorphisms (SNPs) illumina array designed for linkage analysis. We conducted linkage analysis of plasma Aβ levels. None of the linkage analyses yielded genome-wide significant logarithm of odds (LOD) score over 3.3, but there was suggestive evidence for linkage (LOD > 1.9) for two regions: 1q41 (LOD = 2.07) and 11q14.3 (LOD = 2.97), both for Aβ40. These regions were followed up with association analysis in the study subjects and in 320 subjects from a population-based cohort. For the Aβ40 region on chromosome 1, association of several SNPs was observed at the presenilin 2 gene (PSEN2) (p = 2.58 × 10(-4) for rs6703170). On chromosome 11q14-21, we found some association (p = 3.1 × 10(-3) for rs2514299). This linkage study of plasma concentrations of Aβ40 and Aβ42 yielded two suggestive regions, of which one points toward a known locus for familial AD.

Extracellular deposition of amyloid beta peptide (Aβ) has been implicated as a critical step in the pathogenesis of Alzheimer's disease (AD). In Down syndrome (DS), Alzheimer's disease is assumed to be caused by the triplication and overexpression of the gene for amyloid precursor protein (APP), located on chromosome 21. Plasma concentrations of Aβ1-40 and Aβ1-42 were determined in a population based study of 506 persons with DS, who were screened annually for dementia. We used Cox proportional hazards models to determine the risk of dementia. Demented persons with DS have a significantly higher plasma Aβ1-40 concentration than the nondemented (p = 0.05). Those with the highest concentrations of Aβ1-40 and Aβ1-42 have a higher risk to develop dementia. The risk to develop dementia during follow-up (mean 4.7 years) increased to 2.56 (95% confidence interval, 1.39-4.71) for Aβ1-42 and 2.16 (95% confidence interval, 1.14-4.10) for Aβ1-40. High plasma concentration of plasma Aβ1-40 and Aβ1-42 are determinants of the risk of dementia in persons with DS., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The Generation R Study is a population-based prospective cohort study from fetal life until adulthood. The study is designed to identify early environmental and genetic causes and causal pathways leading to normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on six areas of research: (1) maternal health; (2) growth and physical development; (3) behavioural and cognitive development; (4) respiratory health and allergies; (5) diseases in childhood; and (6) health and healthcare for children and their parents. Main exposures of interest include environmental, endocrine, genetic and epigenetic, lifestyle related, nutritional and socio-demographic determinants. In total, n = 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. Response at baseline was 61 %, and general follow-up rates until the age of 6 years exceed 80 %. Data collection in mothers, fathers and children include questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome and epigenome wide association screen is available in the participating children. From the age of 5 years, regular detailed hands-on assessments are performed in a dedicated research center including advanced imaging facilities such as Magnetic Resonance Imaging. Eventually, results forthcoming from the Generation R Study contribute to the development of strategies for optimizing health and healthcare for pregnant women and children.

Hypertension is an important determinant of cardiovascular morbidity and mortality and has a substantial heritability, which is likely of polygenic origin. The aim of this study was to assess to what extent multiple common genetic variants contribute to blood pressure regulation in both adults and children and to assess overlap in variants between different age groups, using genome-wide profiling. Single nucleotide polymorphism sets were defined based on a meta-analysis of genome-wide association studies on systolic blood pressure and diastolic blood pressure performed by the Cohort for Heart and Aging Research in Genome Epidemiology (n=29 136), using different P value thresholds for selecting single nucleotide polymorphisms. Subsequently, genetic risk scores for systolic blood pressure and diastolic blood pressure were calculated in an independent adult population (n=2072) and a child population (n=1034). The explained variance of the genetic risk scores was evaluated using linear regression models, including sex, age, and body mass index. Genetic risk scores, including also many nongenome-wide significant single nucleotide polymorphisms, explained more of the variance than scores based only on very significant single nucleotide polymorphisms in adults and children. Genetic risk scores significantly explained ≤1.2% (P=9.6*10(-8)) of the variance in adult systolic blood pressure and 0.8% (P=0.004) in children. For diastolic blood pressure, the variance explained was similar in adults and children (1.7% [P=8.9*10(-10)] and 1.4% [P=3.3*10(-5)], respectively). These findings suggest the presence of many genetic loci with small effects on blood pressure regulation both in adults and children, indicating also a (partly) common polygenic regulation of blood pressure throughout different periods of life.

Background and Purpose: Most studies investigating the genetics of dementia have focused on Alzheimer disease, but little is known about the genetics of vascular dementia. The aim of our study was to identify new loci associated with vascular dementia., Methods: We performed a genome-wide association study in the Rotterdam Study, a large prospective population-based cohort study in the Netherlands. We sought to replicate genome-wide significant loci in 2 independent replication samples., Results: In the discovery analysis of 5700 dementia-free individuals, 67 patients developed incident vascular dementia over a mean follow-up time of 9.3 ± 3.2 years. We showed genome-wide significance for rs12007229, which is located on the X chromosome near the androgen receptor gene (OR, 3.7; 95% CI, 2.3-5.8, per copy of the minor allele; P=1.3 × 10(-8)). This association was further confirmed in 2 independent populations (probability value of combined replication samples=0.024)., Conclusions: Our study shows a novel genetic locus for vascular dementia on the X chromosome. Further replication of this finding is required.

Prion diseases are rare and fatal neurodegenerative disorders that can be sporadic, inherited or acquired by infection. Based on a national surveillance program in the Netherlands we describe here the clinical, neuropathological, genetic and molecular characteristics of 162 patients with neuropathologically confirmed prion disease over a 12-year period (1998-2009). Since 1998, there has been a relatively stable mortality of Creutzfeldt-Jakob disease (CJD) in the Netherlands, ranging from 0.63 to 1.53 per million inhabitants per annum. Genetic analysis of the codon 129 methionine/valine (M/V) polymorphism in all patients with sporadic CJD (sCJD) showed a trend for under-representation of VV cases (7.0%), compared with sCJD cohorts in other Western countries, whereas the MV genotype was relatively over-represented (22,4%). Combined PrP(Sc) and histopathological typing identified all sCJD subtypes known to date, except for the VV1 subtype. In particular, a "pure" phenotype was demonstrated in 60.1% of patients, whereas a mixed phenotype was detected in 39.9% of all sCJD cases. The relative excess of MV cases was largely accounted for by a relatively high incidence of the MV 2K subtype. Genetic analysis of the prion protein gene (PRNP) was performed in 161 patients and showed a mutation in 9 of them (5.6%), including one FFI and four GSS cases. Iatrogenic CJD was a rare phenomenon (3.1%), mainly associated with dura mater grafts. Three patients were diagnosed with new variant CJD (1.9%) and one with variably protease-sensitive prionopathy (VPSPr). Post-mortem examination revealed an alternative diagnosis in 156 patients, most commonly Alzheimer's disease (21.2%) or vascular causes of dementia (19.9%). The mortality rates of sCJD in the Netherlands are similar to those in other European countries, whereas iatrogenic and genetic cases are relatively rare. The unusual incidence of the VV2 sCJD subtype compared to that reported to date in other Western countries deserves further investigation.

Purpose: Age-related macular degeneration (AMD) is a major cause of blindness in older adults and has a genetically complex background. This study examines the potential association between single nucleotide polymorphisms (SNPs) in the glucose transporter 1 (SLC2A1) gene and AMD. SLC2A1 regulates the bioavailability of glucose in the retinal pigment epithelium (RPE), which might influence oxidative stress-mediated AMD pathology., Methods: Twenty-two SNPs spanning the SLC2A1 gene were genotyped in 375 cases and 199 controls from an initial discovery cohort (the Amsterdam-Rotterdam-Netherlands study). Replication testing was performed in The Rotterdam Study (the Netherlands) and study populations from Würzburg (Germany), the Age Related Eye Disease Study (AREDS; United States), Columbia University (United States), and Iowa University (United States). Subsequently, a meta-analysis of SNP association was performed., Results: In the discovery cohort, significant genotypic association between three SNPs (rs3754219, rs4660687, and rs841853) and AMD was found. Replication in five large independent (Caucasian) cohorts (4,860 cases and 4,004 controls) did not yield consistent association results. The genotype frequencies for these SNPs were significantly different for the controls and/or cases among the six individual populations. Meta-analysis revealed significant heterogeneity of effect between the studies., Conclusions: No overall association between SLC2A1 SNPs and AMD was demonstrated. Since the genotype frequencies for the three SLC2A1 SNPs were significantly different for the controls and/or cases between the six cohorts, this study corroborates previous evidence that population dependent genetic risk heterogeneity in AMD exists.

Objective: We investigated the accuracy of self-reported family history for diabetes, hypertension, and overweight against two reference standards: family history based on physician-assessed health status of relatives and on self-reported personal health status of relatives., Study Design and Setting: Subjects were participants from the Erasmus Rucphen Family study, an extended family study among descendants of 20 couples who lived between 1850 and 1900 in a southwest region of the Netherlands and their relatives (n=1,713). Sensitivity and specificity of self-reported family history were calculated., Results: Sensitivity of self-reported family history was 89.2% for diabetes, 92.2% for hypertension, and 78.4% for overweight when family history based on relatives' self-reported personal health status was used as reference and 70.8% for diabetes, 67.4% for hypertension, and 77.3% for overweight when physician-assessed health status of relatives was used. Sensitivity and specificity of self-reported personal health status were 76.8% and 98.8% for diabetes, 38.9% and 98.0% for hypertension, and 80.9% and 75.7% for overweight, respectively., Conclusion: The accuracy of self-reported family history of diabetes and hypertension is strongly influenced by the accuracy of self-reported personal health status of relatives. Raising awareness of personal health status is crucial to ensure the utility of family history for the assessment of risk and disease prevention., (Copyright © 2012 Elsevier Inc. All rights reserved.)