Loeys–Dietz syndrome

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Loeys-Dietz syndrome
Classification and external resources
OMIM 609192 610168 608967 610380
DiseasesDB 34032
GeneReviews

Loeys–Dietz syndrome (LDS) is an autosomal dominant genetic connective tissue disorder. The disorder is marked by aneurysms in the aorta, often in children. The aorta may also undergo sudden dissection in the weakened layers of the wall of aorta. Aneurysms and dissections also can occur in arteries other than the aorta. Because anurysms in children tend to rupture early, children are at greater risk for dying if the syndrome is not identified. Surgery to repair aortic aneurysms is essential for treatment.

There are four types of the syndrome, labelled types I through IV, which are distinguished by their genetic cause. Type 1, Type 2, Type 3, and Type 4 are caused by mutations in TGFBR1, TGFBR2, SMAD3, and TGFB2 respectively. These four genes encoding transforming growth factors play a role in cell signaling that promotes growth and development of the body's tissues. Mutations of these genes cause production of proteins without function. Although the disorder has an autosomal pattern of inheritance, this disorder results from a new gene mutation in 75% of cases and occurs in people with no history of the disorder in their family.

It has features similar to Marfan syndrome and Ehlers-Danlos syndrome.[1][2][3]

It was identified and characterized by pediatric geneticists Bart Loeys and Harry Dietz at Johns Hopkins University in 2005.

Types[edit]

Several genetic causes of Loeys–Dietz syndrome have been identified. A de novo mutation in TGFB3, a ligand of the TGF ß pathway, was identified in an individual with a syndrome presenting partially overlapping symptoms with Marfan Syndrome and Loeys-Dietz Syndrome.[4]

Type Gene Locus OMIM Description
1A TGFBR1 9q22 609192 Also known as Furlong disease
1B TGFBR2 3p22 610168
2A TGFBR1 9q22 608967
2B TGFBR2 3p22 610380 Previously known as Marfan syndrome type 2
3 SMAD3 613795 Also known as Aneurysms-osteoarthritis syndrome

Symptoms[edit]

Main clinical symptoms of Loeys–Dietz syndrome arterial tortuosity, widely spaced eyes (hypertelorism), wide or split uvula, and aneurysms at the aortic root. Arterial tortuosity are arteries that twist and wind. Other symptoms include cleft palate the white of the eyes appearing blue or gray. Symptoms at birth include heart defects and club foot. There is considerable variability in the symptoms associated with Loeys-Dietz syndrome. Some people can be severely affected, while others only show mild symptoms.

Many of the physical findings typical in Loeys–Dietz syndrome are also found in Marfan syndrome cases, including increased risk of ascending aortic aneurysm and aortic dissection, abnormally long limbs and fingers, and dural ectasia (a gradual stretching and weakening of the dura mater that can cause abdominal and leg pain). However, it also has some additional traits not typical of Marfan patients, including widely spaced eyes, a split uvula in the back of the throat, and skin findings such as easy bruising or abnormal scars.

Other findings can include:

Diagnosis[edit]

Diagnosis involves consideration of physical features and genetic testing. Because different people express different combinations of symptoms and the syndrome was identified in 2005, many doctors may not be aware of its existence.

Treatment[edit]

As there is no known cure, Loeys–Dietz syndrome is a lifelong condition. Due to the high risk of death from aortic aneurysm rupture, patients should be followed closely to monitor aneurysm formation, which can then be corrected with interventional radiology or vascular surgery.

Previous research in laboratory mice has suggested that the angiotensin II receptor antagonist losartan, which appears to block TGF-beta activity, can slow or halt the formation of aortic aneurysms in Marfan syndrome. A large clinical trial sponsored by the National Institutes of Health is currently underway to explore the use of losartan to prevent aneurysms in Marfan syndrome patients. Both Marfan syndrome and Loeys–Dietz syndrome are associated with increased TGF-beta signaling in the vessel wall. Therefore, losartan also holds promise for the treatment of Loeys–Dietz syndrome.

See also[edit]

References[edit]

  1. ^ Loeys BL, Schwarze U, Holm T et al. (2006). "Aneurysm syndromes caused by mutations in the TGF-beta receptor". N. Engl. J. Med. 355 (8): 788–98. doi:10.1056/NEJMoa055695. PMID 16928994. 
  2. ^ LeMaire SA, Pannu H, Tran-Fadulu V, Carter SA, Coselli JS, Milewicz DM (2007). "Severe aortic and arterial aneurysms associated with a TGFBR2 mutation". Nature clinical practice. Cardiovascular medicine 4 (3): 167–71. doi:10.1038/ncpcardio0797. PMC 2561071. PMID 17330129. 
  3. ^ Loeys BL, Chen J, Neptune ER et al. (March 2005). "A syndrome of altered cardiovascular, craniofacial, neurocognitive and skeletal development caused by mutations in TGFBR1 or TGFBR2". Nat. Genet. 37 (3): 275–81. doi:10.1038/ng1511. PMID 15731757. 
  4. ^ Rienhoff HY, Yeo C-Y, Morissette R, Khrebtukova I, Melnick J, Luo S, Leng N, Kim Y-J, Schroth G, Westwick J, Vogel H, McDonnell N, Hall JG, Whitman M. 2013. A mutation in TGFB3 associated with a syndrome of low muscle mass, growth retardation, distal arthrogryposis, and clinical features overlapping with Marfan and Loeys–Dietz syndrome. Am J Med Genet Part A. 161A:2040–2046.

External links[edit]