Lecture 11 AI generated Flashcards
Describe a traditional observational study in epidemiology.
In a traditional observational study, researchers aim to establish a link between a specific factor (such as dietary factor X) and a particular disease (such as disease Y) without determining causation or accounting for potential confounders.
What is the purpose of Mendelian randomisation studies in epidemiology?
Mendelian randomisation studies aim to identify genetic variants associated with certain exposures (e.g., food intake) to investigate their causal relationship with disease outcomes.
How are Mendelian randomisation studies similar to randomised controlled trials?
Mendelian randomisation studies are analogous to randomised controlled trials as genes are considered instrumental variables that are randomly allocated, helping to establish causal relationships.
Define instrumental variable in the context of Mendelian randomisation studies.
An instrumental variable in Mendelian randomisation studies is a genetic variant that is causally related to the exposure being studied (e.g., alcohol consumption) and is independent of potential confounders.
Explain the importance of instrumental variables not being related to the outcome through other pathways in Mendelian randomisation studies.
In Mendelian randomisation studies, it is crucial for instrumental variables to be unrelated to the outcome through other pathways to ensure that the observed relationship between the genetic variant and the exposure is not confounded by other factors.
Describe the AL2 variant and its on alcohol consumption.
Having the ALDH2 variant makes individuals more likely to drink alcohol compared to those who have difficulty metabolizing alcohol.
What is Mendelian randomisation and how is it used in research studies?
Mendelian randomisation is a research method that uses genetic as natural experiments to investigate causal relationships between modifiable risk factors and diseases.
Define epigenetics and DNA methylation.
Epigenetics is a mechanism that regulates gene expression without altering the DNA sequence, while DNA methylation is the addition of a methyl group to DNA, often influencing gene activity.
How does DNA methylation impact gene expression?
DNA methylation, particularly hypermethylation in gene promoter regions, can lead to gene silencing by turning off gene expression.
Explain the concept of the epigenome and its role in gene transcription.
The epigenome is a layer on the genome that acts as a marker determining the transcription of genes into mRNA, regulating when genes are turned on or off.
Describe the process of an Epigenome-Wide Association Study (EWAS).
EWAS involves selecting cases and controls, choosing specific tissues, measuring epigenetic marks at a genome-wide level (specifically CpG sites), and comparing epigenetic differences between cases and controls.
What is the importance of tissue selection in an EWAS?
Tissue selection is crucial in an EWAS due to tissue-specific epigenetic changes; for instance, epigenetic variations in blood may not accurately represent other tissues.
How does cell type heterogeneity impact an EWAS?
Cell type heterogeneity in samples can introduce different epigenetic signatures, potentially affecting the results of an EWAS.
Define Mendelian randomization in the context of epigenetics research.
Mendelian randomization involves using genetic variants as instrumental variables to assess causal relationships between exposures and outcomes, often visualized using a Manhattan plot.
Describe the influence of external factors like nutrients on DNA methylation.
External factors such as nutrients, including methyl donor nutrients like Vitamin D, fatty acids, and alcohol, can influence DNA methylation, as seen in studies on the effects of folic acid and vitamin B12 supplements.
