Genetic epidemiology 15/11/22 Flashcards
What is epidemiology?
Epidemiology is the study of the distribution and determinants of health-related states or events (including disease), and the application of this study to the control of diseases and other health problems.
What is epidemiology used for?
It can provide answers about different groups of people and how different lifestyle factors, access to health care, legislation, cultural, and genetics effect a particular group of people.
What is genetic epidemiology?
*Prevalence and incidence of genetic disorders
* Identifying genetic causes of disease
* Gene environment interaction in genetic disorders
* Treatments for genetic disease: Pharmacogenetics
What is prevalence?
Prevalence is the number of cases of a disease or event present in a defined population at any
particular point in time.
What is incidence?
Incidence is the number of new or newly recorded cases of the disease or events occurring within a
specified time period.
What is prevalence increased by?
-Long duration of disease
-Prolongation if life (without cure)
-Increase in new cases
-In-migration of cases
-Out-immigration of healthy people
-Improved diagnostics
What is prevalence decreased by?
-Shorter duration of disease
-High case-fatality rate
-Decrease in new cases
-In-migration of healthy people
-Out-immigration of cases
-improved cure rate of cases
Can epidemiology facts be trusted globally?
No. Different countries have different testing strategies different access to health care and different ways of reporting statistics therefore global statistics can’t always be treated.
What is a linkage study?
Genetic linkage analysis is a powerful tool to detect the chromosomal location of disease genes. It is based on the observation that genes that reside physically close on a chromosome remain linked during meiosis. We can use these to track segments of DNA through different generations and use this to find out where disease causing genetic variations are located and how the genetic variants are inherited, especially if they are disease causing.
What is transmission disequalibrium?
It is a family-based association test for the presence of genetic linkage between a genetic marker and a trait. A specificity of the TDT is that it will detect genetic linkage only in the presence of genetic association. While genetic association can be caused by population structure, genetic linkage will not be affected, which makes the TDT robust to the presence of population structure.
What is cross-sectional study?
Cross-sectional studies are quick to conduct as compared to longitudinal studies.
A cross-sectional study is conducted at a given point in time.
Cross-sectional study if repeated is conducted with different participants.
Cross-sectional studies cannot pin down cause-and-effect relationship.
Cross-sectional study is comparatively cheaper.
What is a longitudinal study?
Longitudinal studies may vary from a few years to even decades.
A longitudinal study requires a researcher to revisit participants of the study at proper intervals.
Longitudinal study is conducted with the same participants over the years.
Longitudinal study can justify cause-and-effect relationship.
Since the study goes on for years longitudinal study tends to get expensive.
What is a cohort study?
It is a type of longitudinal study where they follow people through life to look at health factors and genetics.
What kind of study do you need when researching a rare disease?
Need a large population size to reflect real life.
What are random errors?
This is when random error happens that introduces noise, but it is completely random, and this effects the reliability. It is a chance difference between the observed and true values of something (e.g., a researcher misreading a weighing scale records an incorrect measurement).
What are systemic errors?
It is a consistent or proportional difference between the observed and true values of something (e.g., a miscalibrated scale consistently registers weights as higher than they actually are).
What is internal validity?
Extent to which the results of the study reflect the true situation in the study sample.
What is external validity?
Are the results of the study applicable to other populations than the study population.
What do researchers want studies to have?
Reliability and validity as it makes it precise and accurate, however, validity is more important.
What is confounding?
Confounding is confusion, or mixing, of effects; the effect of the exposure is mixed together with the effect of another variable, leading to bias.
What is admixture?
Genetic admixture occurs when previously diverged or isolated genetic lineages mix. Admixture results in the introduction of new genetic lineages into a population.
What is linkage disequilibrium?
The non-random association of alleles at different loci in a given population. Things that are physically attached will be inherited together. Linkage disequilibrium (LD) is a population-based parameter that describes the degree to which an allele of one genetic variant is inherited or correlated with an allele of a nearby genetic variant within a given population (Bush and Moore, 2012).
What is Mendel’s law of independent assortment?
Mendel’s law of independent assortment states that the alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene.
What is a haplotype?
A combination of closely linked DNA sequences variants on one chromosome that are often
inherited together.
