Lymphedema-distichiasis syndrome


Lymphedema-distichiasis syndrome

Description, Causes and Risk Factors:

Abbreviation: LDS.

Lymphedema-distichiasis syndrome is a rare primary lymphedema inherited as an autosomal dominant disorder. The characteristic features consist of late onset-lymphedema and distichiasis together with other occasionally seen features including varicose vein, cleft palate, ptosis, and congenital heart diseases.

Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.

Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated "p" and a long arm designated "q". Chromosomes are further sub-divided into many bands that are numbered.

Researchers have determined that lymphedema-distichiasis syndrome occurs due to changers or disruptions (mutations) in the forkhead family transcription factor (FOXC2) gene located on the long arm (q) of chromosome 16 (16q24.3).

By FISH, researchers determined that the translocation breakpoint was within this critical region and further narrowed the breakpoint to a 20-kb interval. Because the translocation did not appear to interrupt a gene, we considered candidate genes in the immediate region that might be inactivated by position effect. In two additional unrelated families with LDS, researchers identified inactivating mutations nonsense mutation and a frameshift mutations in the FOXC2 (MFH-1) gene. FOXC2 is a member of the forkhead/winged-helix family of transcription factors, whose members are involved in diverse developmental pathways. FOXC2 knockout mice display cardiovascular, craniofacial, and vertebral abnormalities similar to those seen in LDS syndrome. Our findings show that FOXC2 haploinsufficiency results in LDS. FOXC2 represents the second known gene to result in hereditary lymphedema, and LDS is only the second hereditary disorder known to be caused by a mutation in a forkhead-family gene.

Lymphedema-distichiasis affects males and females in equal numbers. Lymphedema develops in males at an earlier age than females. The prevalence of this disorder in the general population is unknown. Lymphedema-distichiasis syndrome may go undiagnosed making it difficult to determine its true frequency in the general population.

Symptoms:

Swelling of the legs below the knees is usually seen first, sometimes as early as the first decade of life. It occurs earlier and is more likely associated with other abnormalities in males. The edema is usually confined to the legs and is often asymmetrical. Sores and infections such as cellulitis and athletes' foot are a risk due to the poor circulation. Cardiac defects, cleft palate, cysts of the spinal cord, type II diabetes and kidney disease may be associated with swelling of the arms and legs in some patients.

The eyelashes often grow in duplicated rows but in an abnormal direction that sometimes allows them to rub against the cornea (windshield of the eye). When the later occurs, it causes severe discomfort due to the scratching. Tearing, blurred vision, and light sensitivity often result.

Diagnosis:

The swelling of the arms and legs is due to inadequate drainage of the lymph and can be diagnosed by a physician. The abnormal lashes, though, are difficult to see without a microscopic examination by an ophthalmologist.

A variety of specialized tests may be performed to determine the extent of the disorder. Such tests include lymphoscintigraphy or an echocardiogram. During lymphoscintigraphy, a substance known as a contrast medium is injected into a lymphatic vessel (usually in a hand or foot). A series of x-rays are taken that show the medium as it moves through the lymphatic vessels giving physicians a picture of the health and structure of the lymphatic vessels. During an echocardiogram, reflected sounds waves are used to create an image of the heart, which can reveal congenital heart defects potentially associated with lymphedema-distichiasis syndrome.

Genetic counseling may be of benefit for affected individuals and their families.

Treatment:

Treatment is symptomatic and supportive. The treatment of lymphedema-distichiasis syndrome is directed toward the specific symptoms that are apparent in each individual. Treatment is aimed at reducing swelling and preventing infection. CDT (complete decongestive therapy) is a form of treatment in which specialized massage techniques are coupled with therapeutic bandaging, meticulous skin care, exercise, and the use of well-fitted compression garments such as fitted stockings. Antibiotics may be used to treat recurrent infections such as cellulitis or as a preventive (prophylactic) measure in individuals with recurrent infections.

Distichiasis may be managed with lubrication or plucking (epilation). More definitive treatments for distichiasis include cryotherapy, electrolysis, or lid splitting. Cryotherapy is the application of extreme cold to destroy diseased tissue. Electrolysis uses a short-wave radio frequency to destroy the extra eyelashes. Lip splitting is a surgical procedure in which the eyelid is split open to expose the root (follicle) of the eyelashes. Each extra eyelash is then removed (excised). In some cases, cryotherapy or electrolysis is used in conjunction with lid splitting.

In some cases, surgery may be performed to treat other abnormalities such as ptosis or cleft palate. Individuals with heart abnormalities may be monitored regularly.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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