What causes Loeys-Dietz syndrome?
The cause of Loeys-Dietz syndrome has been determined recently. TGF-beta is a signaling molecule produced in the body that influences the growth, movement, and activity of cells as well as the death of cells by changing the way many genes within the cells are expressed. TGF-beta brings about the changes within cells by binding to receptors on the surfaces of the cells. . Loeys-Dietz syndrome is known to be a result of mutations in the TGF-beta-receptor I (TGFBR1) or II (TGFBR2) genes. The genetic mutations in Loeys-Dietz causes a change in the receptor that prevents TGF-beta from working on the cells. A test is available that can detect the genetic mutation associated with the syndrome; however, the test is not available in most laboratories.
How is Loeys-Dietz syndrome diagnosed?
The diagnosis of aortic aneurysms, including those seen in the Loeys-Dietz syndrome, usually is made by injecting a dye that is visible by X-ray, computerized tomography (CT), or magnetic resonance imaging (MRI) into the blood vessels. X-rays or scans by CT or MRI then are done that show the arteries and aneurysms (because the aneurysms are filled with dye-containing blood). Although aortic aneurysms are the hallmark of Loeys-Dietz Syndrome and the characteristic facial features may suggest the diagnosis, the definitive diagnosis of Loeys-Dietz Syndrome can only be established by the genetic test (described above).
How is Loeys-Dietz syndrome treated?
The only treatment for Loeys-Dietz syndrome to prolong life expectancy is surgical repair of the aortic aneurysm. Surgical repair of the aneurysms is generally successful. Since the aneurysms tend to rupture early, early and accurate diagnosis is critical to ensure that affected individuals receive prompt surgical treatment. The genetic test can be of value in identifying which individuals with aortic aneurysms have Loeys-Dietz syndrome, and therefore, should have immediate surgery. In contrast to Loeys-Dietz syndrome, in other inherited syndromes associated with aortic aneurysms, surgery carries a poorer prognosis, and the aneurysms can be managed with medications for a longer period of time before surgery becomes necessary. Studies are ongoing to determine whether drug treatment of the Loeys-Dietz syndrome also may be of value.
At the time of diagnosis, imaging studies of the aorta are recommended and should be repeated after 6 months to determine if aortic enlargement is occurring. If the diameter of the aorta is not enlarging, yearly magnetic resonance imaging (MRI) scans from the of the circulation from the barin to the pelvis are recommended, since affected persons commonly develop aneurysms that are treatable surgically.
Medically reviewed by Robert J. Bryg, MD; Board Certified Internal Medicine with subspecialty in Cardiovascular Disease
Hiratzka, LF, Bakris, GL, Beckman, JA, et al. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the Diagnosis and Management of Patients With Thoracic Aortic Disease: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine. Circulation 2010; 121:e266.
Loeys BL et al. New England Journal of Medicine, 2006 Aug 24;355(8):788-98.; National Genetics, 2005 Mar;37(3):275-81.