28. Molecular epidemiology

From greek.doctor
  • 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