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Marfan syndrome

 

Gene Reviews

The FBN1 gene provides instructions for making a large protein called fibrillin-1. This protein is transported out of cells into the extracellular matrix, which is an intricate lattice of proteins and other molecules that forms in the spaces between cells. In this matrix, fibrillin-1 binds to other molecules of fibrillin-1 and other proteins to form threadlike filaments called microfibrils. Microfibrils form elastic fibers, which enable the skin, ligaments, and blood vessels to stretch. Microfibrils also provide support to more rigid tissues such as those that support the nerves, muscles, and lenses of the eyes.

Microfibrils store a protein called transforming growth factor beta (TGF-β), a critical growth factor. TGF-β helps control the growth and division of cells, the process by which cells mature to carry out specific functions, cell movement, and the self-destruction of cells. Microfibrils help regulate the availability of TGF-β, which is turned off when stored in microfibrils and turned on  when released.

Most of the mutations that cause Marfan syndrome change a single protein building block in the fibrillin-1 protein. The remaining FBN1 gene mutations result in an abnormal fibrillin-1 protein that cannot function properly. FBN1 gene mutations that cause Marfan syndrome reduce the amount of fibrillin-1 produced by the cell, alter the structure or stability of fibrillin-1, or impair the transport of fibrillin-1 out of the cell. These mutations lead to a severe reduction in the amount of fibrillin-1 available to form microfibrils. Without enough microfibrils, excess TGF-β growth factors are activated and elasticity in many tissues is decreased, leading to overgrowth and instability of tissues. Researchers have identified more than 1,000 FBN1 gene mutations that cause Marfan syndrome.

Patients with this disorder may be exceptionally tall, with long limbs and long thin fingers. The most serious complication is defects of the aortic valves. It may also affect the lungs, eyes, and dural sac surrounding the spinal cord, skeleton and hard plate.

DNA sequencing of the whole coding FBN1 gene mutation can detect approximately 70-93 % patients fulfilling Marfan syndrome diagnostic criteria.

Methodology: Sequencing of entire coding region

Purpose: Confirmation of Clinical Diagnosis

ICD-10 Code Q87.40

Test Requisition: Sequencing Requisition

CPT Code: 81408 Cost: $1595.00

Turn-around-time: 5-6 weeks

Specimen Requirements

Shipping Information

References

1. Brautbar A, LeMaire SA, Franco LM, Coselli JS, Milewicz DM, Belmont JW. (2010) “FBN1 mutations in patients with descending thoracic aortic dissections”.  Am J Med Genet A. 152A(2):413-6.

2. Collod-Béroud G, Boileau C. (2002) “Marfan syndrome in the third Millennium”.  Eur J Hum Genet. 10(11):673-81. Review.

3. Mizuguchi T, Matsumoto N. (2007) “Recent progress in genetics of Marfan syndrome and Marfan-associated disorders”.  J Hum Genet. 52(1):1-12.

 

 

 

 

 


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Genetics Laboratory
University of Oklahoma Health Sciences Center
1122 NE 13 Street, Suite 1400, Oklahoma City, OK 73104
Phone: (405) 271-3589 |Fax: (405) 271-7117 Email: Dr. Shibo Li

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