▁This ▁G W AS - MP E ▁approach ▁can ▁give ▁not ▁only ▁more ▁precise ▁effect ▁estimates , ▁even ▁larger ▁effects , ▁for ▁specific ▁mole cular ▁sub types ▁of ▁the ▁disease , ▁but ▁also ▁ins ights ▁into ▁path ogen esis ▁by ▁linking ▁gen etic ▁variants ▁to ▁mole cular ▁path olog ic ▁sign atures ▁of ▁disease . ▁Since ▁mole cular ▁di agnostics ▁is ▁becoming ▁routine ▁clin ical ▁practice , ▁mole cular ▁path ology ▁data ▁can ▁aid ▁ep ide mi olog ic ▁research . ▁ ▁History ▁ ▁M PE ▁started ▁as ▁analysis ▁of ▁risk ▁factors ▁( such ▁as ▁sm oking ) ▁and ▁mole cular ▁path olog ic ▁find ings ▁( such ▁as ▁K R AS ▁on c ogene ▁mut ation ▁in ▁lung ▁cancer ). ▁ ▁Studies ▁to ▁examine ▁the ▁relationship ▁between ▁an ▁expos ure ▁and ▁mole cular ▁path olog ic ▁signature ▁of ▁disease ▁( part icular ly , ▁cancer ) ▁became ▁increasing ly ▁common ▁throughout ▁the ▁ 1 9 9 0 s ▁and ▁early ▁ 2 0 0 0 s . ▁ ▁The ▁use ▁of ▁mole cular ▁path ology ▁in ▁ep ide mi ology ▁pos ed ▁lack ed ▁standard ized ▁method ologies ▁and ▁gu idel ines ▁as ▁well ▁as ▁inter dis cipl inary ▁exper ts ▁and ▁training ▁programs . ▁M PE ▁research ▁required ▁a ▁new ▁concept ual ▁framework ▁and ▁method ologies ▁( ep ide mi ological ▁method ) ▁because ▁M PE ▁exam ines ▁heter ogene ity ▁in ▁an ▁outcome ▁variable . ▁ ▁The ▁term ▁" m ole cular ▁path ological ▁ep ide mi ology " ▁was