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Gene-environment interactions occur when the
risk of disease in the exposed AND susceptible individuals differs (greater
or less than) from that expected based on their individual effects.
Statisticians sometime define individual effects as only multiplicative.
However, epidemiologists generally examine additive effects as well.
Positive effects that are greater than additive or multiplicative are called
synergistic; negative effects less than additive or multiplicative are
referred to as antagonistic. |