F8 and atrial fibrillation: Another aspect of the genes for which the top genetic variant of Cluster 3 is an eQTL is cardiovascular issues: for instance, mutant CLIC2 leads to atrial fibrillation, cardiomegaly and congestive heart failure20, F8 encodes a large plasma glycoprotein that functions as a blood coagulation factor, whereas mutations in BRCC3 are linked to moyamoya syndrome, a rare blood vessel disorder in which certain arteries in the brain are blocked or constricted, and that is accompanied by other symptoms including hypertension, dilated cardiomyopathy and premature coronary heart disease21.