The primary purpose is to examine the potential interactions of hormone replacement therapy with other procoagulant variants on the risk of cardiovascular events. The main variants of interest are: (la) factor XIIIA Val34Leu; (ib) platelet glycoprotein (PGP) Jib Ile843Ser; (ic) PGP IIIa Leu33Pro; and (id) PGP Ia C807T. The secondary aims include the assessment of other drug-gene, risk-factor-gene or gene-gene interactions on risk: (2a) the interaction between PGP IIb Ser843, PGP lila Leu33Pro and PGP Ia C807T and traditional cardiovascular risk factors such as smoking and obesity on the risk of MI and stroke; (2b) the interaction between three coagulation factor XIII polymorphisms and PAl-1 4G/5G on the risk of stroke in women; and (2c) the interaction between aspirin use and glycoprotein IIIa Leu33Pro on the risk of MI and stroke.