Rs5918

The 'A2' allele of the platelet specific alloantigen system is encoded by rs5918(C), and it has been implicated as increasing the risk of myocardial infarctions, heart disease, and resistance to blood-thinning benefits of aspirin.

On its own, the A2 allele is implicated especially in early onset heart disease ; in combination with the 4G allele of the PAI1 gene, rs1799889, the increased risk of myocardial infarction in a Finnish study population was 4 fold higher (odds ratio = 4.5, p=0.001), particularly in males (odds ratio = 6.4, p=0.0005). Olympic skater Sergei Grinkov, who had this risk factor, died of a heart attack at age 28. 

A2 allele carriers also appear to be relatively resistant to the anti-thrombotic (i.e. anti-clotting) actions normally associated with aspirin use.

A protective effect of rs5918 has also been observed for the development of Non-Hodgkin Lymphoma, both for the SNP (which is also known as L59P) and for its gene, ITGB3. The odds ratio is 0.66 (CI: 0.52-0.85).

rs5918 is not associated with breast cancer risk for either BRCA1 or BRCA2 mutation carriers, based on a multi-center study including ~10,000 patients from 34 studies.