Acetylsalicylic acid is better known as Aspirin. Aspirin is not only a medicinal product against pain, inflammation and fever; in low doses, usually around 100 mg, it prevents blood clotting. This property of Aspirin is exploited to prevent the formation of vessel-occluding blood clots; an occluded vessel may lead to a stroke or a heart attack (i.e. myocardial infarction). The ITGB3 gene governs Aspirin's efficacy in preventing blood clotting.
If a blood clot blocks a vessel that provides nourishment to the heart muscle, a heart attack develops; if the clot occludes a brain-nourishing vessel, however, a stroke follows. Research has shown that the likelihood of a repeat stroke or heart attack can be reduced by 25% when taking Aspirin. Unfortunately, however, Aspirin does not act to prevent the appearance of blood clots in all people; some people suffer another heart attack or stroke sooner and more frequently despite taking Aspirin. Various research studies have indicated that as many as 8%-45% of the people are resistant to the effects of the acetylsalicylic acid. This is called Aspirin resistance and it has many causes. It basically means that Aspirin is unable to suppress the formating of blood clotting factors. Even carriers of merely a tiny change in the ITGB3 gene do not respond to Aspirin. This gene encodes glycoprotein IIIa which is located on the surface of platelets that are essential for blood clotting. Aspirin inefficacy in preventing blood clotting is found in people with the rs5918 (C;C) and rs5918 (C;T) genotypes, and these genotypes can be determined with our analysis.
These individuals also have an increased risk of developing a heart attack. There is a famous case of the two-time Olympic Champion in ice skating, Sergei Grinkov, who suddenly collapsed while training in Lake Placid. Autopsy results showed a severe coronary artery disease and a heart attack, although the athlete did not suffer from hypertension, diabetes mellitus or increased serum lipids. Genetic testing has shown that he was a carrier of the rs5918 (C;T) genotype.