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Molecular and
genetic epidemiology actually represent two separate branches of epidemiology. The terms molecular
and genetic epidemiology are sometimes used interchangeably, however, because one
common application of molecular epidemiology is the use of inherited (vs. acquired)
variation in DNA to classify study subjects. As Friis and Sellers (1999) put it well, the
distinction between the two fields is that “Molecular epidemiology evaluates the
association of variation in known genes with risk of disease, whereas genetic
epidemiology includes the identification of unknown genes that influences risk of
disease.” In addition, molecular epidemiology also uses molecular markers to link
exposures to disease, especially to cancer. Advances in molecular (or genetic) markers
have a great impact on health risk assessment (RA) in that they can be used to flag
preclinical effects of exposure. The advantages of using molecular markers or genetic
factors in RA may be illustrated with the examples provided by Friis and Sellers. For
example, rather than treating all cases of breast cancer as the same disease, an
epidemiologist can use tumor markers to identify potentially more heterogeneous subsets.
Another example is that we can assess serum levels of micronutrients to obtain more
accurate measurements, rather than to rely on the individual’s recall of usual diet to
estimate his or her intake of fruits, vegetables, and the like. |