rs41309764, also known as R1108X, is a SNP in the NOTCH1 gene. The common allele is rs41309764(C), while the rare rs41309764(T) allele encodes the variant.
A normal human heart contains three valves. Carriers of one rs41309764(T) allele, such as Arnold Schwarzenegger, will develop an early developmental defect in the aortic valve leading to a bicuspid aortic valve, and without treatment, they are prone to progressive aortic valve disease in their later life due to calcification.[PMID 16025100]