Smoking and testicular cancer: A Danish nationwide cohort study.

Background: Testicular cancer (TC) incidence has increased worldwide, but specific exposures of TC still need investigation. In this cohort study, we investigated the association between mothers' smoking and the risk of TC in their sons. TC was divided into the morphological subtype seminoma and non-seminomas.

Pre-diagnosis blood DNA methylation profiling of twin pairs discordant for breast cancer points to the importance of environmental risk factors.

Background: Assessment of breast cancer (BC) risk generally relies on mammography, family history, reproductive history, and genotyping of major mutations. However, assessing the impact of environmental factors, such as lifestyle, health-related behavior, or external exposures, is still challenging. DNA methylation (DNAm), capturing both genetic and environmental effects, presents a promising opportunity.

Is Cancer Associated With Frailty? Results From a Longitudinal Study of Old Danish Twins.

Background: Although age is an important risk factor for both cancer and frailty, it is unclear whether cancer itself increases the risk of frailty. We aimed to assess the association between cancer and frailty in a longitudinal cohort of older Danish twins, taking familial effect into account.

Methods: Using the Danish Cancer Registry, cancer cases were identified among participants aged 70 and over in the Longitudinal Study of Aging Danish Twins (LSADT).

Depressive symptoms, cognitive functions and daily activities: An extended network analysis in monozygotic and dizygotic twins.

Background: The network theory posits that depression emerges as the result of individual symptoms triggering each other. Risk factors for depression can impact these between-symptoms interactions through extended networks. The study aimed to model the extended network of depressive symptoms and known depression risk factors - objective cognitive function, intellectual, physical, and social daily activities, and then, compare the observed networks between monozygotic (MZ) and dizygotic (DZ) co-twins.

Novel epigenetic biomarkers for hematopoietic cancer found in twins.

Background And Purpose: This article aims to identify epigenetic markers and detect early development of hematopoietic malignancies through an epigenome wide association study of DNA methylation data.

Materials And Methods: This register-based study includes 1,085 Danish twins with 31 hematopoietic malignancies and methylation levels from 450,154 5'-C-phospate-G-3' (CpG) sites. Associations between methylation levels and incidence of hematopoietic malignancy is studied through time-to-event regression.

Mosaic loss of Y chromosome and the association to mortality in Danish men aged 56-100 years.

Mosaic loss of the Y chromosome (mLOY) is a common somatic mutation in the blood of elderly men and several studies have found mLOY in blood cells to be associated with an increased risk of various diseases and mortality. However, most of these studies have focused on middle-aged and older adults, meaning that mLOY in extremely old individuals like centenarians is understudied. To explore mLOY across a wider age range compared to earlier studies and to specifically focus on centenarians, mLOY was estimated in 917 Danish men aged 56-100 years.

Socioeconomic differences in discrepancies between expected and experienced discomfort from colonoscopy and colon capsule endoscopy.

Background: Social inequalities in colorectal cancer screening participation are evident. Barriers to screening participation include discomfort from diagnostic modalities. We aimed to describe the discomfort experienced from colonoscopy and colon capsule endoscopy (CCE) and investigate the discrepancy between expected and experienced discomfort stratified by socioeconomic status.

Impact of a nationwide school policy on body mass index in Danish school children: An interrupted time series analysis.

Objectives: A new school policy mandating 45 min physical activity daily during school was introduced in Denmark in 2014. We aimed to evaluate the effect of this policy on BMI in school-aged children. It was hypothesized that the school policy would decrease BMI, especially in the obese fraction of the population (90th percentile BMI).

Association of cancer with functional decline at old age: a longitudinal study in Danish twins.

Introduction: There is evidence that older adults with cancer have a higher risk of functional decline than cancer-free older adults. However, few studies are longitudinal, and none are twin studies. Thus, we aimed to investigate the relationship between cancer and functional decline in older adult (aged 70+ years) twins.

A Mass Spectrometry-Based Proteome Study of Twin Pairs Discordant for Incident Acute Myocardial Infarction within Three Years after Blood Sampling Suggests Novel Biomarkers.

Acute myocardial infarction (AMI) is a major cause of mortality and morbidity worldwide, yet biomarkers for AMI in the short- or medium-term are lacking. We apply the discordant twin pair design, reducing genetic and environmental confounding, by linking nationwide registry data on AMI diagnoses to a survey of 12,349 twins, thereby identifying 39 twin pairs (48-79 years) discordant for their first-ever AMI within three years after blood sampling. Mass spectrometry of blood plasma identified 715 proteins.

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Studies on cancer loci by use of twin data reveal sources of variation in risk. The Nordic twin and cancer registries contain the largest cohort of population representative twins ever studied with more than median 40 years of follow-up. This article considers findings that show influences on familial risk and demonstrates the strengths of the matched case co-twin design for unraveling important risk factors of cancers.

Socioeconomic differences in expected discomfort from colonoscopy and colon capsule endoscopy.

Individual income and educational level are associated with participation rates in colorectal cancer screening. We aimed to investigate the expected discomfort from the endoscopic diagnostic modalities of colonoscopy and colon capsule endoscopy in different socioeconomic groups as a potential barrier for participation. In a randomized clinical trial within the Danish colorectal cancer screening program, we distributed questionnaires to 2031 individuals between August 2020 and December 2022 to investigate the expected procedural and overall discomfort from investigations using visual analogue scales.

A robust and fast two-sample test of equal correlations with an application to differential co-expression.

A robust and fast two-sample test for equal Pearson correlation coefficients (PCCs) is important in solving many biological problems, including, for example, analysis of differential co-expression. However, few existing methods for this test can achieve robustness against deviation from normal distributions, accuracy under small sample sizes, and computational efficiency simultaneously. Here, we propose a new method for testing differential correlation using a saddlepoint approximation of the residual bootstrap (DICOSAR).

Identifying genetic variants regulating MGMT gene expression - A study in monozygotic Danish twins.

Identifying genetic factors affecting the regulation of the O-6-Methylguanine-DNA Methyltransferase (MGMT) gene and estimating the genetic contribution of the MGMT gene through within-pair correlation in monozygotic twin pairs is of particular importance in various types of cancer such as glioblastoma. We used gene expression data in whole blood from 448 monozygotic twins from the Middle Age Danish Twins (MADT) study to investigate genetic regulation of the MGMT gene by performing a genome-wide association study (GWAS) of the variation in MGMT expression. Additionally, we estimated within-pair dependence measures of the expression values looking for the genetic influence of significant identified genes.

Small hard drusen and associated factors in early seniority.

Purpose: The purpose of this study was to examine the ocular and systemic risk profile of the fundus phenotype ≥ 20 small hard (macular) drusen (< 63 μm in diameter).

Methods: This single-center, cross-sectional study of 176 same-sex twin pairs aged 30 to 80 (median 60) years was a component of a framework study of the transition from not having age-related macular degeneration to having early AMD. Drusen categories assessed using fundus photography and optical coherence tomography included small hard drusen (diameter < 63 μm), intermediate soft drusen (63-125 μm), and large soft drusen (> 125 μm), of which the soft drusen are compatible with a diagnosis of AMD.

Circulating microRNAs related to lipid metabolism and solid tissue maintenance and morphology associate with mortality in elderly twins.

The lifespan of humans varies greatly between individuals. Here, we aimed to explore what biological roles miRNAs may have on old age mortality-variation. Circulating miRNAs were measured in plasma from 43 monozygotic twin pairs (73-95 years of age) and mortality analyses were applied using Cox regression survival analyses and linear regression analyses of lifespan.

Heritability and Risk Factors of Incident Small and Large Drusen in the Copenhagen Twin Cohort Eye Study: A 20-Year Follow-Up.

Introduction: The transition from a normal fundus to one with early drusen (≥20 small hard drusen) to age-related macular degeneration (AMD) in the form of drusen ≥63 μm in diameter is of interest, because small hard drusen may be precursors of large drusen. Study of AMD precursor lesions may provide valuable insight into factors that initiate AMD. Here, the progression of drusen was studied over an interval of 20 years in a population-based twin cohort.

Cancer-Related Reductions in Survival: Extent and Duration Evaluated Using a Large Cohort Study of Twins, 1943-2011.

Background: The time during which there is an increased risk of death for cancer survivors was evaluated in a large twin study, which allows for matching on shared components such as age, genes, and socioeconomic factors in childhood.

Methods: By use of data from Danish registers, time to death from initial cancer was studied prospectively in twins in two different settings. The twins were diagnosed with at least one cancer in the period 1943 to 2011.

The heritability of BMI varies across the range of BMI-a heritability curve analysis in a twin cohort.

Background: The heritability of traits such as body mass index (BMI), a measure of obesity, is generally estimated using family and twin studies, and increasingly by molecular genetic approaches. These studies generally assume that genetic effects are uniform across all trait values, yet there is emerging evidence that this may not always be the case.

Method/subjects: This paper analyzes twin data using a recently developed measure of heritability called the heritability curve.

Causal relation between heart irradiation and survival of lung cancer patients after radiotherapy.

Introduction: In a recent study, setup uncertainties in the direction of the heart were shown to impact the overall survival of non-small cell lung cancer (NSCLC) patients after radiotherapy, indicating the causal effect between heart irradiation and survival. The current study aims to externally evaluate this observation within a patient cohort treated using daily IGRT.

Method: NSCLC patients with locally-advanced disease and daily CBCT were included.

Heritability of retinal drusen in the Copenhagen Twin Cohort Eye Study.

Purpose: To study age- and sex-adjusted heritability of small hard drusen and early age-related macular degeneration (AMD) in a population-based twin cohort.

Methods: This was a single-centre, cross-sectional, classical twin study with ophthalmic examination including refraction, biometry, best-corrected visual acuity assessment, colour and autofluorescence fundus photography, and fundus optical coherence tomography. Grading and categorization of drusen was by diameter and location.