Important role of the angiotensin II pathway in producing matrix metalloproteinase-9 in human thoracic aortic aneurysms.
To the Editor: In their review on thoracic aortic dilatation associated with bicuspid aortic valve, Verma and Siu (May 15 issue)1 do not mention the increased prevalence of bicuspid aortic valve and its strong association with aortic dilatation and dissection in women with Turner’s syndrome.2 This sex-chromosome disorder, which is caused by the loss of all or part of one X chromosome, affects approximately 1 in 2000 live-born females and approximately 80,000 women in the United States. The prevalence of bicuspid aortic valve in Turner’s syndrome (approximately 1 in 3) is much greater than that in the general population and is frequently accompanied by other cardiovascular complications, such as dilatation or coarctation of the thoracic aorta.3 Its presence also increases the risk of aortic dissection and occurs more frequently, at younger ages, and during pregnancy in patients with Turner’s syndrome.4,5 Investigation of bicuspid aortic valve in patients with Turner’s syndrome may provide generalizable insights into the contribution of X chromosome genes to bicuspid aortic valve in men, in whom increased susceptibility to bicuspid aortic valve may be due in part to a reduced dose of X chromosome genes. The unique association among bicuspid aortic valve, aortic disease, and Turner’s syndrome is clearly important. Angela E. Lin, M.D.