There are two types of lymphedema. Although the cause is not well understood, primary lymphedema is thought to result from an inherited abnormality of the lymphatic system. Secondary lymphedema is the result of a damaged or blocked lymphatic system caused by traumas such as surgery or injury.
Age of onset tends to be similar within families.
Primary lymphedema seems to be inherited in several different ways. Milroy's and Meige's Disease are two forms of primary lymphedema that tend to show swelling below the waist and are dominantly inherited in some families. When the first signs of swelling appear after age 35, this condition is called lymphedema tarda. A recessive form of lymphedema has also been described, as well as lymphedema in association with other traits. Except for genes on the sex chromosomes, both men and women have two copies of each gene.