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Organizations

• International Federation of Marfan Syndrome Organizations
• National Marfan Foundation
• Canadian Marfan Association
• Marfan Association UK
• Marfan Network Japan
• More National Organizations...

Genetics of the Marfan Syndrome

FBN1 Gene

The disorder is caused by mutations or changes in one of a pair of genes called fibrillin genes.  These are located on one of the 23 pairs of human chromosomes.  The FBN1 gene is a large protein that can cause more than 300 mutations. These mutations can lead to the rare condition known as Marfan Syndrome.

The fibrillin 1 or FBN1 gene produces a protein called fibrillin.  This protein attaches itself to the other proteins and molecules in your body. It also controls the growth and repair of your tissues and internal organs.  Fibrillin is necessary for the formation of elastic fibers in your connective tissue.

A mutation in the FBN1 gene reduces the amount or quality of fibrillin, Without the proper support, the connective tissues can become weak or tear.  The faulty fibrillin weakens the connective tissue and ligaments connecting the heart, eyes, bones and lungs throughout your body.

 

TGFBR2 Gene

Some researchers also believe that Marfan Syndrome is caused by a mutation in the TGFBR2 gene.  Mutations in this particular gene are referred to as “Marfan Syndrome Type II.”

This gene helps your body make a protein that transmits signals from the outside to the inside of a cell. This process affects the division and growth of the cells throughout your body. The TFGFBR2 gene changes the signaling activity of the protein which affects the growth and development of the connective tissue within your body.

 

Autosomal Dominant Pattern

Marfan Syndrome is a condition inherited in what is called an “autosomal dominant pattern.”  Basically, this means the disorder is usually inherited from a parent who already has the disease.  At least one copy of an altered gene is necessary to cause the disorder.

A mother or father who already has Marfan Syndrome, will have a 50% chance of producing a child who is also affected by the disorder.  If both parents have Marfan Syndrome, the odds increase to 75% that their children will be born with the condition.

The disease can also be affected by “double dominance.”  This term refers to a very rare instance where a parent has two copies of a dominant gene rather than just one.  If either the father or mother is double dominant, they usually have a 100% chance of passing Marfan Syndrome on to their offspring.

At least 25 percent of the cases of Marfan Syndrome result from a new or sporadic mutation in the FBN1 gene that was not present in either parent.  This is called a “sporadic genetic disease” and it can occur even if there is no previous family history of the disorder.