FA Fact Sheet
Fanconi anemia (FA), named for Swiss pediatrician, Guido Fanconi, is one of the inherited disorders that can lead to bone marrow failure (aplastic anemia), leukemia, and solid tumors. FA is almost exclusively 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.
While the total number of FA patients is not documented worldwide, scientists estimate that the carrier frequency (carriers are people carrying a defect in one copy of a particular FA gene, whose other copy of that same FA gene is normal) for FA in the U.S. is 1 in 181. The incidence rate, or the likelihood of a child being born with FA, is about 1 in 131,000 in the U.S., with approximately 31 babies born with FA each year.
Scientists have now discovered 16 FA genes [FANCA, -B, -C, -D1 (also known as BRCA2), D2, E, F, G, I, J, L, M, N, O, P and Q]. Mutations in these genes account for more than 95% of reported Fanconi anemia cases. Mutations in FANCA, FANCC and FANCG are the most common and account for approximately 85% of FA patients worldwide. FANCD1, FANCD2, FANCE, FANCF and FANCL account for 10%, while the remaining FA genes, FANCB, FANCI, FANCJ, FANCM, FANCN, FANCO, FANCP, and FANCQ represent less than 5%. Some individuals with FA do not appear to have mutations in these 16 genes, so we anticipate that additional FA genes will be discovered in the future.
FA occurs equally in males and females, except for FANCB patients who are exclusively male. It is found in all ethnic groups. Though considered primarily a blood disease, it may affect all systems of the body. Most patients develop bone marrow failure, necessitating a stem cell transplant. Many patients develop acute myelogenous leukemia (AML) or Myelodysplastic Syndrome (MDS). Patients who live into adulthood are extremely likely to develop head and neck, gynecologic, and/or gastrointestinal cancer which occur at a much earlier age (20s, 30s, and 40s) than the general population. Patients who have had a successful stem cell transplant and, thus, are cured of the blood problems associated with FA still must have regular examinations to watch for signs of cancer. Some patients do not reach adulthood; 80% reach age 18 or more. The current median lifespan is 33 years, with some patients living into their 30s, 40s, and 50s.
Fanconi anemia patients are usually smaller than average and some have developmental defects, including thumb and arm anomalies. FA usually reveals itself before children are 12 years old, but in rare cases no symptoms are present until adulthood. First signs of FA may be extreme fatigue, frequent infections, nosebleeds or easy bruising. Blood tests may reveal a low white, red cell or platelet count or other abnormalities, defined medically as anemia. Sometimes MDS or AML is the first sign of FA. On occasion, FA isn’t diagnosed until cancer (usually the type called squamous cell carcinoma) has been identified.
At least 60% of FA patients are born with at least one physical anomaly. This may include:
- Short stature
- Thumb and arm anomalies: an extra or misshapen or missing thumbs and fingers or an incompletely developed or missing radius (one of the forearm bones)
- Skeletal anomalies of the hips, spine or ribs
- Kidney problems
- Skin discoloration (café-au-lait spots); portions of the body may have a suntanned look
- Small head or eyes
- Mental retardation or learning disabilities
- Low birth weight
- Gastrointestinal difficulties
- Small reproductive organs in males
- Defects in tissues separating chambers of the heart
The definitive test for FA at the present time is a chromosome breakage test. Chromosomes are structures in the body that are made up of DNA. For the test, some of the patient’s blood cells are treated, in a test tube, with a chemical that fuses different strands of DNA together (called crosslinkers). Normal cells are able to correct most of this type of DNA damage by unfusing the DNA strands and are not severely affected whereas FA cells are unable to break apart the strands of DNA and their chromosomes snap or break. There are two chemicals commonly used for this test: 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 are not diagnosed in a timely manner. FA should be suspected and tested for in anyone born with thumb/arm abnormalities and anyone developing aplastic anemia at any age, even if no other defects are present. Any patient who develops cancers of the head and neck, gynecologic system or gastrointestinal system (squamous cell carcinoma or adenocarcinoma) at an early age and without a history of tobacco or alcohol use, should be tested for FA. Many FA patients show no other abnormalities and therefore all siblings of FA patients (even those apparently unaffected) should be tested. It is absolutely essential to test for FA before contemplating stem cell transplantation for aplastic anemia or treatment for cancer, as standard chemotherapy and radiation protocols may prove toxic to FA patients.
**Rosenberg, P. S., Tamary, H. and Alter, B. P. (2011), How high are carrier frequencies of rare recessive syndromes? Contemporary estimates for Fanconi Anemia in the United States and Israel. American Journal of Medical Genetics Part A, 155: 18771883. doi: 10.1002/ajmg.a.34087