['Peroxisome proliferator-activated receptor alpha (PPARalpha) regulates the expression of genes involved in lipid metabolism and inflammation, making it a candidate gene for atherosclerosis and ischemic heart disease (IHD).', 'We investigated the association between the leucine 162 to valine (L162V) polymorphism and a G to C transversion in intron 7 of the PPARalpha gene and progression of atherosclerosis in the Lopid Coronary Angiography Trial (LOCAT), a trial examining the effect of gemfibrozil treatment on progression of atherosclerosis after bypass surgery and on risk of IHD in the second Northwick Park Heart Study (NPHS2), a prospective study of healthy middle-aged men in the United Kingdom. There was no association with plasma lipid concentrations in either study. Both polymorphisms influenced progression of atherosclerosis and risk of IHD. V162 allele carriers had less progression of diffuse atherosclerosis than did L162 allele homozygotes with a similar trend for focal atherosclerosis. Intron 7 C allele carriers had greater progression of atherosclerosis than did G allele homozygotes. The V162 allele attenuated the proatherosclerotic effect of the intron 7 C allele. Homozygotes for the intron 7 C allele had increased risk of IHD, an effect modulated by the L162V polymorphism'] Do peroxisome proliferator-activated receptor alpha gene variants influence progression of coronary atherosclerosis and risk of coronary artery disease?