About Fanconi anemiaFanconi anemia (FA) is one of the inherited anemias that leads to bone marrow failure (aplastic anemia). It is primarily a recessive disorder: if both parents carry a defect (mutation) in the same FA gene, each of their children has a 25% chance of inheriting the defective gene from both parents. When this happens, the child will have FA.
Fanconi anemia usually reveals itself before children are 12 years old, but in rare cases no symptoms are present until adulthood. Fanconi anemia patients are usually smaller than average. They may feel extreme fatigue and have frequent infections. Nosebleeds or easy bruising may be a first sign of the disease. Blood tests may reveal a low white cell, red cell or platelet count or other abnormalities. Sometimes myelodysplasia, AML, or squamous cell carcinoma in a young adult is the first sign of FA.
FA sometimes is evident at birth through a variety of physical defects. These may include any of the following:
Testing for FA:
The definitive test for FA at the present time is a chromosome breakage test: some of the patient's blood cells are treated, in a test tube, with a chemical that crosslinks DNA. Normal cells are able to correct most of the damage and are not severely affected, whereas FA cells show marked chromosome breakage. The two chemicals commonly used for this test are DEB (diepoxybutane) and MMC (mitomycin C). These tests can be performed prenatally on cells from chorionic villi or from the amniotic fluid.
Many cases of FA are not diagnosed at all or not diagnosed in a timely manner. FA should be suspected and tested for in any infant born with the thumb and arm abnormalities described previously. Anyone developing aplastic anemia at any age should be tested for FA, even if no other defects are present. Many FA patients show no other abnormalities. It is absolutely essential to test for FA before contemplating bone marrow transplantation for aplastic anemia. The regimen used to prepare patients for transplant is very different for FA patients as FA patients tolerate radiation and chemotherapy very poorly.
While the total number of FA patients is not documented worldwide, scientists estimate that the carrier frequency (carriers are people carrying the defect in an FA gene, whose matching FA gene is normal) for FA is somewhere between 1 in 600 and 1 in 100. The International Fanconi Anemia Registry managed by Dr. Arleen Auerbach at The Rockefeller University maintains case data on at least 3,000 patients.
Treatment for Fanconi anemai includes the following:
Approximately half of FA patients respond well to androgens (male hormones), which stimulate the production of red blood cells, and often, platelets. Sometimes white cell production is stimulated as well. This treatment may be effective for many years, but most patients eventually fail to respond. It is essential that the use of androgens is considered in the context of an eventual bone marrow transplant, as their use may affect adversely the ultimate success of a transplant.
Hematopoietic (blood-stimulating) growth factors are also used. G-CSF stimulates the production of white blood cells and seems to be effective in FA patients. Other growth factors may be effective in combination.
Bone marrow transplantation:
At the present time, this is the only long-term cure for the blood defects in FA. This treatment has many risks associated with it, and the risks are compounded in FA patients because of their extreme sensitivity to radiation and chemotherapy. The consensus of the physicians who participated in March 2003 in the development of the handbook Fanconi Anemia: Standards for Clinical Care is that, if a transplant center has had experience with fewer than 5 matched sibling donor transplants for FA, strong consideration should be given for referral to a transplant center with significant experience in transplants for FA. FA patients often experience complications which are not routine for other transplants, such as a marked increased risk in organ toxicity and in graft-verus-host disease (GVHD) and development of glucose intolerance, with most FA patients requiring insulin therapy.
Relationship to Cancer:
People with Fanconi anemia often develop leukemia and other cancers. In fact, Fanconi anemia patients have a much greater risk of developing acute myelogenous leukemia (AML) than people without Fanconi anemia.
Leukemia is a malignancy of the blood system in which the bone marrow produces vast quantities of immature white cells called "blasts." The blasts can proliferate rapidly and suppress the development of healthy blood cells needed for effective functioning of the patient's body. If untreated, leukemia results in uncontrollable infections and bleeding, and death. The type of leukemia that FA patients are likely to develop, AML, is a particularly aggressive type, usually found in older people. AML is difficult to treat successfully, especially in FA patients, who are very sensitive to the toxic drugs used to suppress the leukemia.
Fanconi anemia patients have an extremely high risk of developing squamous cell cancers in areas of the body in which cells normally reproduce rapidly, such as the oral cavity, esophagus, the gastrointestinal tract, the anus and vulva. FA patients may develop these cancers at a much earlier age than people without Fanconi anemia. Patients who have had a successful bone marrow transplant and, thus, are cured of the blood problems associated with FA, still must have regular examinations to watch for signs of cancer.