Irritable bowel syndrome

ronmentalinfluences,adjustingforage,werederivedfrom the twin data. Results: Heritability for AD was estimated to be 58% in the full model and 79% in the best-fitting model, with the balance of variation explained by nonshared environmental influences. There were no significant differences between men and women in prevalence or heritability after controlling for age. Within pairs concordant for AD, intrapair difference in age at onset was significantlygreaterindizygoticthaninmonozygoticpairs,suggesting genetic influences on timing of the disease. Conclusions: In the largest twin study to date, we confirmed that heritability for AD is high and that the same genetic factors are influential for both men and women. However, nongenetic risk factors also play an important role and might be the focus for interventions to reduce disease risk or delay disease onset. Arch Gen Psychiatry. 2006;63:168-174

https://jamanetwork.com/journals/jamapsychiatry/articlepdf/209307/YOA40625.pdf

Role of Genes and Environments for Explaining Alzheimer Disease

The saimie paper suggests how susceptible individuals could reduce their total intake of aluminium. In presenting the cpidemiological evidence for a link betveen aluminium and Alzheimcr's, Nart'n suggests that although definite proof is still lacking, there is more than enough positixe evidence to fuel further epidemiological investigation. It states that such investigations might specificallx address the issue of the confounding cffect of silicon and an assessment of exposure to spccific

https://jech.bmj.com/content/jech/47/6/511.4.full.pdf

Methodology for Genetic Studies of Twins and Families

Consistent but indirect evidence has implicated genetic factors in smoking behavior1,2. We report meta-analyses of several smoking phenotypes within cohorts of the Tobacco and Genetics Consortium (n = 74,053). We also partnered with the European Network of Genetic and Genomic Epidemiology (ENGAGE) and Oxford-GlaxoSmithKline (Ox-GSK) consortia to follow up the 15 most significant regions (n > 140,000). We identified three loci associated with number of cigarettes smoked per day. The strongest association was a synonymous 15q25 SNP in the nicotinic receptor gene CHRNA3 (rs1051730[A], b = 1.03, standard error (s.e.) = 0.053, beta = 2.8 x 10(-73)). Two 10q25 SNPs (rs1329650[G], b = 0.367, s. e. = 0.059, beta = 5.7 x 10(-10); and rs1028936[A], b = 0.446, s. e. = 0.074, beta = 1.3 x 10(-9)) and one 9q13 SNP in EGLN2 (rs3733829[G], b = 0.333, s. e. = 0.058, P = 1.0 x 10(-8)) also exceeded genome-wide significance for cigarettes per day. For smoking initiation, eight SNPs exceeded genome-wide significance, with the strongest association at a nonsynonymous SNP in BDNF on chromosome 11 (rs6265[C], odds ratio (OR) = 1.06, 95% confidence interval (Cl) 1.04-1.08, P = 1.8 x 10(-8)). One SNP located near DBH on chromosome 9 (rs3025343[G], OR = 1.12, 95% Cl 1.08-1.18, P = 3.6 x 10(-8)) was significantly associated with smoking cessation.

https://cdr.lib.unc.edu/downloads/sq87bw60k

Genome-wide meta-analyses identify multiple loci associated with smoking behavior

Twin studies have been a valuable source of information about the genetic basis of complex traits. To maximize the potential of twin studies, large, worldwide registers of data on twins and their relatives have been established. Here, we provide an overview of the current resources for twin research. These can be used to obtain insights into the genetic epidemiology of complex traits and diseases, to study the interaction of genotype with sex, age and lifestyle factors, and to study the causes of co-morbidity between traits and diseases. Because of their design, these registers offer unique opportunities for selected sampling for quantitative trait loci linkage and association studies.

/pdf/classical-twin-studies-and-beyond-1pzo429juq.pdf

Classical twin studies and beyond.

. Lichtenstein P, de Faire U, Floderus B, Svartengren M, Svedberg P, Pedersen NL (Karolinska Institutet; Karolinska Hospital; Institute of Environmental Medicine, Karolinska Institutet, National Institute for Working life, Stockholm, Sweden; and University of Southern California, CA, USA) The Swedish Twin Registry: a unique resource for clinical, epidemiological and genetic studies (Review). J Intern Med 2002; 252: 184–205.

The Swedish Twin Registry (STR), which today hasdeveloped into a unique resource, was first established in the late 1950s to study the importance of smoking and alcohol consumption on cancer and cardiovascular diseases whilst controlling for genetic propensity to disease. Since that time, the Registry has been expanded and updated on several occasions, and the focus has similarly broadened to most common complex diseases. In the following, we will summarize the content of the database, describe for the first time recent data collection efforts and review some of the principal findings that have come from the Registry.

https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2796.2002.01032.x

The Swedish Twin Registry: a unique resource for clinical, epidemiological and genetic studies.

Education, income, and occupation are factors known to affect health and disease. In this review we describe the Swedish Longitudinal Integrated Database for Health Insurance and Labour Market Studies (LISA, Longitudinell Integrationsdatabas for Sjukforsakrings- och Arbetsmarknadsstudier). LISA covers the adult Swedish population aged ≥ 16 years registered on December 31 each year since 1990 (since 2010 individuals aged ≥ 15 years). The database was launched in response to rising levels of sick leave in the country. Participation in Swedish government-administered registers such as LISA is compulsory, and hence selection bias is minimized. The LISA database allows researchers to identify individuals who do not work because of injury, disease, or rehabilitation. It contains data on sick leave and disability pension based on calendar year. LISA also includes information on unemployment benefits, disposable income, social welfare payments, civil status, and migration. During 2000–2017, an average of 97,000 individuals immigrated to Sweden each year. This corresponds to about 1% of the Swedish population (10 million people in 2017). Data on occupation have a completeness of 95%. Income data consist primarily of income from employment, capital, and allowances, including parental allowance. In Sweden, work force participation is around 80% (2017: overall: 79.1%; men 80.3% and women 77.9%). Education data are available in > 98% of all individuals aged 25–64 years, with an estimated accuracy for highest attained level of education of 85%. Some information on civil status, income, education, and employment before 1990 can be obtained through the Population and Housing Census data (FoB, Folk- och bostadsrakningen).

/pdf/the-longitudinal-integrated-database-for-health-insurance-18k0hjy9ac.pdf

The longitudinal integrated database for health insurance and labour market studies (LISA) and its use in medical research

The association between dementia and education was studied in 143 twin pairs discordant for dementia, using a matched-pair design, and in 221 dementia cases and 442 unrelated controls from the same twin registry, using a case-control design. Low education was defined as 6 years or less of schooling. Case-control analyses with prevalent cases showed low education to be a risk for Alzheimer's disease but not dementia in general. Low education did not significantly predict incident cases. In the matched-pairs analysis, which controls for genetic and other familial influences, differences in education between demented twins and twin partners were not statistically significant. However, for Alzheimer's disease, odds ratios resulting from matched pairs and case-control analyses were similar. Twins' comparative reports about intellectual involvement earlier in their lives suggest a long-standing difference on this dimension, with less involvement by the twin who became demented.

/pdf/education-and-the-risk-of-alzheimer-s-disease-findings-from-y4nouwzlft.pdf

Education and the Risk of Alzheimer's Disease Findings From the Study of Dementia in Swedish Twins

Since the Swedish Twin Registry was first established in the late 1950s to study the importance of smoking and alcohol consumption on cancer and cardiovascular diseases, it has been expanded and updated on several occasions. The focus has similarly broadened to most common complex diseases. The content of the database is described, ongoing projects based on the registry are summarized, and we review some of the principal findings on aging, cancer and cardiovascular disease that have come from the registry. Ongoing efforts and future plans for the STR are discussed. Among others, we plan blood collection and genotyping to study the genetic bases of complex diseases, a first contact ever with the cohorts born after 1958, and in-depth studies of selected diseases, such as Parkinson's disease and chronic fatigue syndrome.

/pdf/the-swedish-twin-registry-in-the-third-millennium-35o3iebv2h.pdf

The Swedish Twin Registry in the Third Millennium

The aim of this study was to investigate what psychosocial predictors, life-style factors and health behaviors in early adulthood are of importance for self-ratings of health after the age of 45. Like-sexed adult twins born 1926-1950 (n = 16,080) from the Swedish Twin Registry that participated in a questionnaire in 1973 and in a telephone interview conducted between 1998 and 2002 were included. Exposure data was collected in 1973 and information on self-rated health and covariates was collected at the second contact 25 years later. Logistic regression using Generalized Estimating Equations was used to evaluate the associations. Conditional logistic regression was used to control for familial and genetic effects in the sample. Pain, lack of exercise, smoking, obesity, unemployment, perceived stress and personality are associated with future poor self-rated health, after controlling for age, sex, illness, education and socio-economic status. Familial and genetic effects influence the associations between recurrent headache, exercise, obesity, and poor self-rated health. Overall, these findings provide support for long-term effects of health behavior and psychosocial risk factors on poor self-ratings of health, beyond the influence of obvious health consequences such as disorders or illnesses. Genetic and familial factors are of importance only for some of these associations.

Pia Svedberg

Papers

The Swedish Twin Registry: a unique resource for clinical, epidemiological and genetic studies.

The longitudinal integrated database for health insurance and labour market studies (LISA) and its use in medical research

Education and the Risk of Alzheimer's Disease Findings From the Study of Dementia in Swedish Twins

The Swedish Twin Registry in the Third Millennium

A prospective study of health, life-style and psychosocial predictors of self-rated health.