Turner Syndrome (TS) is a rare cytogenetic disorder caused by the partial or complete loss of a second sex chromosome, which occurs in about 1 in 2,000 female live births. The most common cause of early mortality in TS is due to congenital heart defects. Bicuspid Aortic Valve (BAV) is the most common congenital heart defect in the general population with a prevalence of 0.5-2%. TS patients have the highest burden of BAV with a prevalence around 30% with near complete penetrance of aortic disease. Little is known about why there is such a large increase of BAV in TS. TS is associated with genome wide hypomethylation when compared to karyotypically normal female and male controls. Epigenetic alterations in BAV have been found with changes identified in circulating miRNAs and in DNA methylation profiles of primary aortic tissue. We hypothesize that BAV is associated with DNA methylation alterations in TS.