Autosomal Dominant: Marfan Syndrome
We inherit genes from our biological parents in specific ways. One way is called autosomal dominant inheritance.
Autosomal dominant inheritance means that the gene in question is located on one of the autosomes. These are numbered pairs of chromosomes, 1 through 22. (These chromosomes do not determine an offspring's gender.) "Dominant" means that only one gene from one parent is necessary to pass down a trait or disorder. When a parent has a dominant trait or disorder, there is a 50 percent chance that any child they have will also inherit the trait:
Click Image to Enlarge
Marfan syndrome occurs in one in 5,000 live births. It is a connective tissue disorder associated with autosomal dominant inheritance. Connective tissue is abundant in the body and is important as a supporting structure. It is especially important for the musculoskeletal system. It also provides support for other body systems as well, including the eyes and heart. The gene for Marfan syndrome is called fibrillin-1. It is localized to chromosome #15 on the long arm (q) at 15q21.1.
Common findings in individuals with Marfan syndrome include those related to connective tissue disorders. These include abnormal enlargement of the aortic root of the heart, dislocated lenses of the eyes, and a tall, lanky body with increased joint mobility, scoliosis, long flat feet, and long fingers. Findings may vary among individuals diagnosed with this condition, even within a family.
If an individual carries an abnormal gene for Marfan syndrome, that individual has a 50 percent risk of passing down the disorder to each future offspring. If a person does not carry the gene abnormality, then the risk for occurrence of the disorder in future offspring is the same as for the general population.
Click here to view the
Online Resources of Medical Genetics