28. Molecular epidemiology
- Molecular epidemiology focuses on the contribution and interaction of genetic and environmental risk factors, identified at the molecular level, to disease
- Uses techniques of molecular biology, like PCR, next generation sequencing (NGS), ELISA, western blot, etc.
- Aims to identify:
- Biomarkers of genetic susceptibility
- Biomarkers of exposure
- Biomarkers of effect
- Biomarkers of disease
- Genetic susceptibility
- Some genotypes are protective against a risk factor, meaning that exposure causes less risk for disease than the general population
- Some genotypes are susceptible against a risk factor, meaning that exposure causes more risk for disease than the general population
- Example study 1: “Associations between XRCC1 and ERCC2 polymorphisms and DNA damage in peripheral blood lymphocyte among coke oven workers” (Leng et al, 2004)
- Showed that certain differences (polymorphisms) in the genes XRCC1 and ERCC2 were associated with decreased DNA-repair capacity toward PAH-induced DNA damage
- Example study 2: “Urinary 1-hydroxypyrene concentrations in Chinese coke oven workers relative to job category, respirator usage, and cigarette smoking” (Chen et al, 2007)
- Showed that smoking oven workers had higher urinary concentration of 1-hydroxypyrene than non-smokers
- 1-hydroxypyrene is a marker of air pollution exposure
- NAT2 is a gene involved in biotransformation of drugs (more here)
- Some people have a slow version of the gene (slow acetylators)
- Some people have a rapid version of the gene (rapid acetylators)
- Studies have shown that slow acetylators have higher risk of CRC
- Polymorphisms in p53, mEH and XRCC1 are also associated with CRC
- Polymorphisms in GSTM and NAT2 influence the amount of DNA damage accumulated based on diet
- Rapid acetylators sustain more DNA damage during a meat-containing diet than slow acetylators
- GSTM1 negative people sustain more DNA damage during a meat-containing diet than GSTM1 positive people