Lymph vessels are small channels, like blood vessels, that carry a clear fluid called lymph. Lymphedema is a swelling caused by a buildup of lymph fluid in tissue that is not normal.  As the fluid builds up, it causes swelling in the arms and legs. This buildup of fluid is due to a faulty lymph system or blockage of the lymph vessels. 

When an infant or child has lymphedema, it is called primary lymphedema.   

The two types of primary lymphedema are idiopathic (unknown cause) and hereditary. Hereditary lymphedema is present at birth and may be a link to other syndromes (anomalies) as well.  The most common form of primary lymphedema is called Milroy’s disease, or lymphedema praecox. This condition can be present at birth, or a child can begin to have symptoms during puberty.

We are closer to finding the genetic basis for these disorders. Some mutations in the vascular endothelial growth factor receptor (VEGFR3) have been found, and others are being looked into.

Lymphedema linked to a trauma, infection or surgical removal of lymph nodes is called secondary lymphedema. 

All patients with lymphedema should meet with a genetic counselor.