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Turner syndrome (TS) is due to haploinsufficiency for genes located on the sex chromosome short arms. There is a high rate of fetal demise in mid-late gestation resulting from aortic arch hypoplasia, and interruption and coarctation of the aorta, often associated with a bicuspid aortic valve (BAV) and left-heart hypoplasia. In fact, TS is the most common known genetic disorder associated with left-heart hypoplasia, coarctation of the aorta, and BAV. Surviving individuals with TS exhibit distinctive aortic arch abnormalities consistent with impaired development of 4th pharyngeal arch arteries. Aortic valve defects, ranging from partial fusion of the right and left coronary leaflets to BAV and unicuspid aortic valves, are common and associated with dilation of the ascending aorta. These abnormalities are associated with a high risk for aneurysms and dissection of both ascending and descending thoracic aortas in young adults with TS. |
