Lymph fluid is continually drained & filtered through the lymph nodes to remove bacteria, toxins & dead cells by lymphatic system. The filtered fluid is drained back to the bloodstream via lymphatic vessels. Lymphedema is the swelling caused when there is impairment of the lymphatic system to drain this fluid from the tissues.
Is Lymphedema Hereditary?
Lymphedema can be classified into two types:
Primary Lymphedema: Primary lymphedema is a hereditary condition in which the lymphatic system is anomalous & does not develop properly prior to birth. The symptoms of primary lymphedema are not always present at the time of birth. In some cases, they can develop as late as in adulthood.
Secondary Lymphedema: Secondary lymphedema condition is mostly caused by damage/blockage of lymphatic system or other environmental factors including surgery, radiation, infection or injury. It is the most common type of lymphedema.
Hereditary Lymphedema Causes, Signs & Symptoms
Hereditary lymphedema is also known as primary lymphedema. It can be subcategorized into congenital hereditary lymphedema (hereditary lymphedema type I, Milroy disease) lymphedema praecox (hereditary lymphedema type II, Meige disease), & lymphedema tarda.
Hereditary lymphedema is inherited as autosomal dominant traits. Milroy’s disease is associated with mutation in the FLT4 gene, which encodes for vascular endothelial growth factor receptor 3 (VEGFR-3) & Meige disease is associated with the mutation of ‘forkhead’ family transcription factor (FOXC2) gene.
There is gathering of lymphatic fluid in the subcutaneous tissue due to malformation, obstruction or underdevelopment of the lymphatic vessels.
The most common associated symptom of hereditary lymphedema is edema (swelling) of various parts of the body, particularly lower extremities & genitalia due to gathering of protein rich lymph fluid in the interstitial tissues. Apart from swelling of the lower extremities and/or genitalia, there also might be swelling of the upper extremities, trunk & face. In lower extremities, usually, both the extremities are affected & the swelling is most noticeable in the foot & ankle, but it is not uncommon to see swollen thighs. This swelling is the cause of discomfort, feeling of tightness & paresthesias (tingling sensation) in the affected region. The affected region shows poor wound healing after a minor trauma (such as a cut or insect bite). The skin of the affected region might become hyperkeratosed with dry, thick & scaly skin that gives the appearance of “woody” texture.
Milroy’s disease (type IA hereditary lymphedema) is characteristic of congenital swelling; however, there have been rare cases in which edema develops later in life. Lower extremities are the most commonly affected site, but genitals might also be affected. Milroy’s disease might also show signs of up-slanting toenails, papillomatosis, prominent leg veins, urethral abnormalities & hydrocele in scrotum.
Meige disease (hereditary lymphedema type 2, lymphedema praecox) usually develops around puberty or early adulthood. Additionally to edema of the legs, genitals, arms, larynx & face might also be affected including development of yellow nails. This is the most common type of hereditary lymphedema accounting for approximately 80% of the cases.
Lymphedema tarda is the hereditary lymphedema that occurs in late adulthood, usually, after 35 years of age.
Diagnosis & Treatment
Currently, there is no gene therapy available for hereditary lymphedema as well as no approved medication for the treatment of lymphedema. The treatment of lymphedema is aimed at reducing swelling & preventing infection. Complete decongestive therapy (CDT) is used to manage lymphedema by manual lymph drainage along with compression bandaging, skin care, conditioning exercise & compression garments. Antibiotics can be used for recurrent infections or prophylactically & antifungals can be used for Athlete’s foot.
Various surgical techniques have also been adopted to treat hereditary lymphedema including microsurgical anastomosis for rechanneling the lymph fluid into the venous system & reducing operations for the removal of excessive fibrotic tissue in severe cases of lymphedema.