By: Gary Taubes
Date: August 28, 2018
- Study and analysis of the distribution, patterns and determinants of health and disease conditions in defined populations.
- How often diseases occur in different groups of people and why.
- Can’t always answer fundamental questions, especially related to chronic diseases.
- Because: correlation is not causation.
- Hard to determine which correlations are causal and which are not
- Mendelian randomization.
- Uses innate genetic differences between people to investigate the causal relations between potentially modifiable risk factors and health outcomes in observational data.
- Naturally occurring randomized controlled trials.
- Genotypes are passed down randomly from parents to their offspring.
- Risk of pleiotropy:
- Potential that gene variants have more than one specific phenotypic effect.
- Therefore, important that the gene variant influences only trait of interest.
- If multiple traits are influenced => risk of confounding.
- Epidemiology: high HDL is associated with lower risk of heart disease.
- MR: however, those of us born with genes that raise our HDL do not have fewer heart attacks.
- Conclusion: HDL may be correlated with heart disease, but HDL likely does not play a causal role.
- Additional source:
- Database and analytical platform for Mendelian randomization: