The Epidemiology of Genetic Epidemiology

1992 ◽  
Vol 41 (4) ◽  
pp. 261-273 ◽  
Author(s):  
J.L. Hopper
Keyword(s):  
Genetic Epidemiology ◽  
Familial Aggregation ◽  
Familial Risk ◽  
Twin Studies ◽  
Statistical Modelling ◽  
Twin Design ◽  
The Past ◽  
Increased Risk ◽  
Familial Risk Factors ◽  
Related Individuals

AbstractFamilial aggregation for disease is important; strong familial risk factors must exist even if the increased risk to a relative of an affected individual is modest. It is in practice difficult, however, to conduct studies in genetic epidemiology which conform to strict epidemiological principles. For twin studies there are two major questions: Are twins ‘no different’ from the population on which inference is to be made? Are study twins ‘no different’ to twins in the population? The importance of each question of bias depends on the scientific question, the trait(s) studied, and sampling issues. The strength of the twin design is its ability to refute the null hypothesis that genetic factors do not explain variation in a trait. Following the Popperian paradigm, alternate hypotheses should be considered in depth (both theoretically and empirically), with a design and sample size sufficient to exclude not just naive explanations. More sophisticated statistical techniques are now being applied, so the philosophy, assumptions, and limitations of statistical modelling must be appreciated. The concept of ‘heritability’ has, in the past, been misunderstood and misused. New advances in DNA technology promise to revolutionise epidemiological thinking, and so case-control-pedigree designs may well become standard tools. The strengths and limitations of studies based on related individuals as the sampling unit are discussed.

scholarly journals The Evolving Field of Genetic Epidemiology: From Familial Aggregation to Genomic Sequencing

2019 ◽  
Vol 188 (12) ◽  
pp. 2069-2077
Author(s):  
Priya Duggal ◽  
Christine Ladd-Acosta ◽  
Debashree Ray ◽  
Terri H Beaty
Keyword(s):  
Genetic Epidemiology ◽  
Disease Risk ◽  
Familial Aggregation ◽  
Rna Expression ◽  
Entire Genome ◽  
The Past ◽  
Future Challenges ◽  
The Individual ◽  
Study Designs ◽  
Health Applications

Abstract The field of genetic epidemiology is relatively young and brings together genetics, epidemiology, and biostatistics to identify and implement the best study designs and statistical analyses for identifying genes controlling risk for complex and heterogeneous diseases (i.e., those where genes and environmental risk factors both contribute to etiology). The field has moved quickly over the past 40 years partly because the technology of genotyping and sequencing has forced it to adapt while adhering to the fundamental principles of genetics. In the last two decades, the available tools for genetic epidemiology have expanded from a genetic focus (considering 1 gene at a time) to a genomic focus (considering the entire genome), and now they must further expand to integrate information from other “-omics” (e.g., epigenomics, transcriptomics as measured by RNA expression) at both the individual and the population levels. Additionally, we can now also evaluate gene and environment interactions across populations to better understand exposure and the heterogeneity in disease risk. The future challenges facing genetic epidemiology are considerable both in scale and techniques, but the importance of the field will not diminish because by design it ties scientific goals with public health applications.

scholarly journals Genomics of ageing in twins

2014 ◽  
Vol 73 (4) ◽  
pp. 526-531 ◽  
Author(s):  
Massimo Mangino
Keyword(s):  
Molecular Mechanisms ◽  
Twin Studies ◽  
Later Life ◽  
Twin Design ◽  
The Past ◽  
Human Ageing ◽  
Classical Twin Design ◽  
Environmental Component ◽  
Early Life Events ◽  
Generation Sequencing

Ageing is a complex multifactorial process, reflecting the progression of all degenerative pathways within an organism. Due to the increase of life expectancy, in recent years, there is a pressing need to identify early-life events and risk factors that determine health outcomes in later life. So far, genetic variation only explains ~20–25 % of the variability of human survival to age 80+. This clearly implies that other factors (environmental, epigenetic and lifestyle) contribute to lifespan and the rate of healthy ageing within an individual. Twin studies in the past two decades proved to be a very powerful tool to discriminate the genetic from the environmental component. The aim of this review is to describe the basic concepts of the twin study design and to report some of the latest studies in which high-throughput technologies (e.g. genome/epigenome-wide assay, next generation sequencing, MS metabolic profiling) combined with the classical twin design have been applied to the analysis of novel ‘omics’ to further understand the molecular mechanisms of human ageing.

Familial risk factors and the familial aggregation of psychiatric disorders

1990 ◽  
Vol 20 (2) ◽  
pp. 311-319 ◽  
Author(s):  
Kenneth S. Kendler
Keyword(s):  
Risk Factors ◽  
Risk Factor ◽  
Psychiatric Disorders ◽  
Genetic Factors ◽  
Familial Aggregation ◽  
Familial Risk ◽  
Significant Proportion ◽  
Potential Importance ◽  
Obstetric Injury ◽  
Familial Risk Factors

SynopsisAll major psychiatric disorders aggregate in families. For most disorders, both genes and environmental factors play an important role in this aggregation. While recent work has tended to concentrate on the importance of genetic factors, this report focuses on the potential importance of environmental risk factors which themselves aggregate in families. In particular, this article examines how much of the familial aggregation of a psychiatric disorder may result from the familial aggregation of a risk factor. The model is illustrated and then applied to putative familial risk factors for schizophrenia and depression. The results of the model suggest that if parental loss and exposure to pathogenic rearing practices are true risk factors for depression, then they could account for a significant proportion of the familial aggregation of depression. By contrast, the model predicts that even if obstetric injury and low social class are true risk factors for schizophrenia, they together would account for only a very small proportion of the tendency for schizophrenia to aggregate in families.

Co-morbidity and familial aggregation of alcoholism and anxiety disorders

1998 ◽  
Vol 28 (4) ◽  
pp. 773-788 ◽  
Author(s):  
K. R. MERIKANGAS ◽  
D. E. STEVENS ◽  
B. FENTON ◽  
M. STOLAR ◽  
S. O'MALLEY ◽  
...  
Keyword(s):  
Anxiety Disorders ◽  
Alcohol Dependence ◽  
Social Phobia ◽  
Familial Aggregation ◽  
Familial Risk ◽  
Family History Information ◽  
Self Medication ◽  
Co Morbidity ◽  
History Information ◽  
Familial Risk Factors

Background. This study examined the patterns of familial aggregation and co-morbidity of alcoholism and anxiety disorders in the relatives of 165 probands selected for alcoholism and/or anxiety disorders compared to those of 61 unaffected controls.Methods. Probands were either selected from treatment settings or at random from the community. DSM-III-R diagnoses were obtained for all probands and their 1053 first-degree relatives, based on direct interview or family history information.Results. The findings indicate that: (1) alcoholism was associated with anxiety disorders in the relatives, particularly among females; (2) both alcoholism and anxiety disorders were highly familial; (3) the familial aggregation of alcoholism was attributable to alcohol dependence rather than to alcohol abuse, particularly among male relatives; and (4) the pattern of co-aggregation of alcohol dependence and anxiety disorders in families differed according to the subtype of anxiety disorder; there was evidence of a partly shared diathesis underlying panic and alcoholism, whereas social phobia and alcoholism tended to aggregate independently.Conclusions. The finding that the onset of social phobia tended to precede that of alcoholism, when taken together with the independence of familial aggregation of social phobia and alcoholism support a self-medication hypothesis as the explanation for the co-occurrence of social phobia and alcoholism. In contrast, the lack of a systematic pattern in the order of onset of panic and alcoholism among subjects with both disorders as well as evidence for shared underlying familial risk factors suggests that co-morbidity between panic disorder and alcoholism is not a consequence of self-medication of panic symptoms. The results of this study emphasize the importance of examining co-morbid disorders and subtypes thereof in identifying sources of heterogeneity in the pathogenesis of alcoholism.

Suicidal Behavior in Surviving Co-Twins

2006 ◽  
Vol 9 (5) ◽  
pp. 642-645 ◽  
Author(s):  
Maurizio Pompili ◽  
Piera Maria Galeandro ◽  
David Lester ◽  
Roberto Tatarelli
Keyword(s):  
Suicidal Behavior ◽  
Genetic Factors ◽  
Familial Risk ◽  
Strong Support ◽  
Twin Studies ◽  
Close Relative ◽  
Sudden Loss ◽  
Increased Risk ◽  
Suicidal Attempts ◽  
Mz Twins

AbstractRecent research has provided strong support for the existence of a familial risk for suicide, and efforts have been made to separate genetic from enviromental risk factors. Twin studies have played a major role in the identification of genetic factors, and the results indicate that the concordance rate for suicide is higher in identical than in fraternal twins (Baldessarini & Hennen, 2004). Moreover, Segal and Roy (1995) reported a significantly higher frequency of nonfatal suicidal attempts by monozygotic (MZ) than by dyzygotic (DZ) twins whose co-twins had committed suicide. However, doubts remain as to whether the increased risk of suicide in MZ twins is a response to the intense grief over the loss of a close relative, or whether a common genotype is associated with suicidal behavior. Sudden loss, which may carry a stigma in the case of a suicide, has been linked to increased persistent emotional stress and physiological changes (Epstein, 1993; Martin & Dean, 1993). A number of researchers have reported greater suicidal ideation among bereaved MZ twins as compared to DZ twins, suggesting that a loss due to suicide may increase the risk of suicidal behavior in the surviving co-twin (Segal & Bouchard, 1993; Segal & Roy, 1995; Segal et al., 1995). The aim of the present article is to address the issue of the intense grief experienced by twins after the co-twin suicide.

Violent crime runs in families: a total population study of 12.5 million individuals

2010 ◽  
Vol 41 (1) ◽  
pp. 97-105 ◽  
Author(s):  
T. Frisell ◽  
P. Lichtenstein ◽  
N. Långström
Keyword(s):  
Violent Crime ◽  
Interpersonal Violence ◽  
Familial Aggregation ◽  
Violent Behavior ◽  
Familial Risk ◽  
Violence Risk ◽  
Specific Effects ◽  
Familial Risk Factors ◽  
Risk Assessment And Prevention ◽  
Nested Case Control

BackgroundEtiological theory and prior research with small or selected samples suggest that interpersonal violence clusters in families. However, the strength and pattern of this aggregation remains mostly unknown.MethodWe investigated all convictions for violent crime in Sweden 1973–2004 among more than 12.5 million individuals in the nationwide Multi-Generation Register, and compared rates of violent convictions among relatives of violent individuals with relatives of matched, non-violent controls, using a nested case–control design.ResultsWe found strong familial aggregation of interpersonal violence among first-degree relatives [e.g. odds ratio (OR)sibling 4.3, 95% confidence interval (CI) 4.2–4.3], lower for more distant relatives (e.g. ORcousin 1.9, 95% CI 1.9–1.9). Risk patterns across biological and adoptive relations provided evidence for both genetic and environmental influences on the development of violent behavior. Familial risks were stronger among women, in higher socio-economic strata, and for early onset interpersonal violence. There were crime-specific effects (e.g. ORsibling for arson 22.4, 95% CI 12.2–41.2), suggesting both general and subtype-specific familial risk factors for violent behavior.ConclusionsThe observed familiality should be accounted for in criminological research, applied violence risk assessment, and prevention efforts.

Vitamin A: dietologist’s position

2020 ◽  
pp. 49-57
Author(s):  
S. V. Orlova ◽  
E. A. Nikitina ◽  
L. I. Karushina ◽  
Yu. A. Pigaryova ◽  
O. E. Pronina
Keyword(s):  
Immune Response ◽  
Urinary Tract ◽  
Gastrointestinal Tract ◽  
Vitamin A ◽  
Developed Countries ◽  
Therapeutic Practice ◽  
The Past ◽  
Increased Risk ◽  
Mucous Membranes

Vitamin A (retinol) is one of the key elements for regulating the immune response and controls the division and differentiation of epithelial cells of the mucous membranes of the bronchopulmonary system, gastrointestinal tract, urinary tract, eyes, etc. Its significance in the context of the COVID‑19 pandemic is difficult to overestimate. However, a number of studies conducted in the past have associated the additional intake of vitamin A with an increased risk of developing cancer, as a result of which vitamin A was practically excluded from therapeutic practice in developed countries. Our review highlights the role of vitamin A in maintaining human health and the latest data on its effect on the development mechanisms of somatic pathology.

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