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Fanconi Anemia (FA)
Sunday, 27 July 2003
Monday, 04 December 2006

What

Fanconi anemia (FA) is an inherited disorder that leads to progressive bone marrow failure. Bone marrow is the part of bone that produces blood cells and cells that function in the immune system. In FA, the bone marrow becomes unable to produce all of these types of cells. Fanconi anemia may also be associated with physical signs including alterations in skin pigment, short stature, and limb length differences. Signs and symptoms can vary with each person.

Who

Fanconi anemia is a genetic condition which has equal prevalence in both sexes. It affects people of all racial and ethnic backgrounds, with an increased incidence in Ashkenazi Jews and Afrikaners. The median age of diagnosis is 7-8 years, but those having birth defects are diagnosed earlier. Most children begin to show symptoms of bone marrow impairment between 2 and 15 years old but a small number of individuals do not show symptoms until their twenties or thirties.

Signs and Symptoms

Some children with FA have no observable physical signs at birth while others are born with physical differences that may include:

  • Low birth weight.
  • Small patches of darker skin (café-au-lait spots). There may also be patches where pigment is absent and the skin looks white.
  • Short stature.
  • Small head or eyes and differing ear shape or position.
  • Learning disabilities or delays or slowness in learning compared to peers.
  • Absent or malformed kidneys.
  • Heart defects.
  • Decreased reproductive organ size in males.
  • Intestinal problems.
  • Limb differences including extra or absent thumbs and lack of or incompletely formed arm bones.
  • Some children also have lower limb differences and spine or rib alterations. While many children are born without most or all of the above physical signs, more than 90% of children with FA start to develop bone marrow failure by their early teens. Symptoms caused by decreased bone marrow function are listed below:
  • Nosebleeds or easy bruising. (Usually develops first.)
  • Infections or illnesses that occur more often than usual.
  • Excessive fatigue due to anemia or low red blood cell count.

Possible Causes

Defects in at least 11 genes are known to cause FA by rendering the body’s cells unable to repair damaged DNA or unable to rid itself of certain damaging molecules. Every child has two copies of each of these 11 genes—one copy is from the child’s mother and one from the child’s father. In order for a child to be affected by the disease, that child must inherit an altered copy of the same FA gene from both mom and dad. For example if the child’s parents, who are unaffected by the disease, each have one normal copy of an FA gene and one altered copy, they can each give either the normal copy or the altered copy to the child. The determination of which gene is given to the child is totally random. In the general population, between 1 in 100 to 600 people have one altered copy of an FA gene, known as the carrier state. It is unclear exactly how the genetic defects in Fanconi anemia lead to bone marrow failure. As the bone marrow fails, blood cells and components known as platelets, white blood cells, and red blood cells that are produced by the bone marrow decrease in number. Platelets help to prevent bleeding, so when their numbers become low, injury to small blood vessels can cause easy bruising. White blood cells are the component of the body’s immune system that protect against infection. A low white blood cell count makes the body more susceptible to infection. Red blood cells carry oxygen to the body’s tissues, thus decreased red cell numbers cause fatigue. In every person, DNA is naturally damaged over time and cells are often subjected to damaging molecules known as oxygen-free radicals. Since the genetic changes in Fanconi anemia hinder cells’ ability to repair damaged DNA, patients with FA are at increased risk for DNA damage that can lead to cancers such as leukemia.

Diagnosis

The definitive test for FA is a chromosome breakage analysis. Chromosomes are long segments of DNA. In this test, a blood sample is taken from a patient and subjected to chemicals that damage DNA in the cells. Patients with FA have DNA that is more easily damaged so their chromosomes show increased breakage. This test is usually performed if certain physical abnormalities are observed at birth or if a complete blood count (in which different types of blood cells are counted and reported) demonstrates numbers that could indicate bone marrow failure. There are other causes of bone marrow failure in addition to FA, so chromosome breakage analysis is needed to confirm a FA diagnosis. Parents with a family history of FA can have their fetus screened for the disease through chorionic villus sampling (in which a small tissue sample is taken from the sac where the baby grows) or amniocentesis (in which a needle is inserted into the amniotic fluid surrounding the baby).

Treatment

Bone marrow failure may be cured with a bone marrow transplant in which a donor’s bone marrow is transplanted into an FA patient. However, in order to have a bone marrow transplant, a matching donor must be found. The best donor is a sibling whose bone marrow is a match. Bone marrow failure cure rates with transplant are greater than 80% with a matched sibling donor, but are less than 50% without a matched sibling donor. As with any procedure, there are risks with bone marrow transplantation. Those risks are increased in FA patients because they are more susceptible to the DNA damage caused by radiation and chemotherapy that must be given prior to bone marrow transplant. However, if a matching sibling donor is available, bone marrow transplant is the treatment of choice as it has a high probability of curing progressive bone marrow failure. For patients without a bone marrow donor, treatment with androgens, which are male hormones, encourages blood cell production by the bone marrow. This treatment may be beneficial for many years, but not all patients respond to androgen therapy. Unfortunately, over time, androgens stop working for most patients who initially showed a positive response. Growth factors that stimulate blood cell production may also be beneficial. Research is being done in the area of gene therapy with the hope that it will lead to additional treatment or cures. Periodic blood transfusions may also be needed as bone marrow starts to fail. Additionally, as FA patients are susceptible to cancer, frequent cancer screenings are needed. Also, patients born with impairments at birth will likely need additional treatments apart from those used to alleviate bone marrow failure.

Prognosis

The prognosis for children with FA is highly variable, with bone marrow failure being the major cause of death in these patients. Bone marrow failure progresses over months to years and currently, it can only be cured by bone marrow transplant. However, a bone marrow transplant cannot cure other cells in the body of their defects. FA patients who have had a bone marrow transplant are still at increased risks for developing cancers, especially acute myelogenous leukemia, skin, head and neck, liver, and esophageal cancers. Frequent screenings can help detect these cancers early. Despite the severity of their condition, FA patients are living longer with most patients surviving 2 to 25 years. A number of female patients have had children of their own. There is a great deal of variability in survival and each case is different.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

Fanconi Anemia Research Fund, Inc.
Excellent resource which includes an overview of the disease, links to a Fanconi anemia handbook published in English and Spanish, information on getting support from other families affected by the disease, details about ongoing research, and links to other FA websites.

Family Village
A nice website with links to other informative sites.

United Kingdom Fanconi Anaemia Co.
Gives a detailed discussion of FA along with links to support groups, ongoing research and other informational websites. This site also has a 'kids' section dedicated to children with the disorder.

Google Search for Fanconi Anemia (FA)

References and Sources

www.emedicine.com/ped/topic3022.htm www.fanconi.org Freedman MH, Chapter 18—“Inherited Forms of Bone Marrow Failure,” pp. 261-267, Hoffman: Hematology: Basic Principles and Practice, 3rd ed. on-line at home.mdconsult.com/das/book/29255166/view/1053/143.html/top, 2000. Matsui W, “Fanconi’s Anemia,” on-line from MEDLINE plus at www.nlm.nih.gov/medlineplus/ency/article/000334.htm, 2002. Pizzo PA, D’Andrea AD, Chapter 474—“The Constitutional Pancytopenias,” p. 1495-1497, Behrman: Nelson Textbook of Pediatrics, 16th ed., on-line at home.mdconsult.com/das/book/29232709/view/873/1164.html/top, 2000. Robertson KA, Chapter 135—“Clinical Indications,” p. 637, Behrman: Nelson Textbook of Pediatrics, 16th ed., on-line at home.mdconsult.com/das/book/29255166/view/873/666.html/top, 2000.