The present invention provides compositions and methods based on genetic polymorphisms that are associated with coronary heart disease (particularly myocardial infarction), aneurysm/dissection, and/or response to drug treatment, particularly statin treatment. For example, the present invention relates to nucleic acid molecules containing the polymorphisms, variant proteins encoded by these nucleic acid molecules, reagents for detecting the polymorphic nucleic acid molecules and variant proteins, and methods of using the nucleic acid molecules and proteins as well as methods of using reagents for their detection.