How Is Fanconi Anemia Diagnosed?

People who have Fanconi anemia (FA) are born with the disease. They may or may not show signs or symptoms of it at birth. For this reason, FA isn't always diagnosed when a person is born. In fact, most people with the disease are diagnosed between the ages of 2 and 15 years.

The tests used to diagnose FA depend on a person's age and symptoms. In all cases, medical history and family history are an important part of diagnosing FA. However, because FA has many of the same signs and symptoms as other diseases, only genetic testing can confirm its diagnosis.

Specialists Involved

A geneticist is a doctor or scientist who studies how genes work and how diseases and different traits are passed from parents to children through their genes. Geneticists do genetic testing for FA and can provide counseling about how FA is inherited and the types of prenatal (before birth) testing used to diagnose it.

An obstetrician may detect birth defects linked to FA before your child is born. After your child is born, a pediatrician also can help determine whether your child has FA.

A hematologist—an expert in diagnosing and treating blood conditions—also may help diagnose FA.

Family and Medical History

FA is an inherited disease. Some parents are aware that their family has a medical history of FA, even if they don't have the disease. Other parents, especially if they're carriers, may not be aware that there is any history of FA in their families. Many parents may not know that FA can be passed from parents to children.

Information on your family's medical history is very important to help your doctor diagnose whether you or your child has FA or another type of condition with similar symptoms.

If your doctor suspects that you, your siblings, or your children have FA, he or she may ask you detailed questions about any personal or family history of anemia, surgeries related to your digestive system, or diseases of the immune system. Your doctor also may ask you about your appetite, eating habits, and the medicines you take.

If you know your family has a history of FA, or if your answers to your doctor 's questions suggest a possible diagnosis of FA, your doctor will order further testing.

Diagnostic Tests and Procedures

The signs and symptoms for FA aren't unique to the disease. They're also linked to many other diseases and conditions, such as aplastic anemia. For this reason, genetic testing is needed to confirm a diagnosis of FA. Genetic tests for FA include the following.

Chromosome Breakage Test

This is the most common test for FA. It's available only in special laboratories. It shows whether your chromosomes (long chains of genes) break more easily than normal.

Sometimes, skin cells are used for the test, but usually a small amount of blood is taken from a vein in your arm with a needle. A technician combines some of the blood cells that were taken out with certain chemicals. If you have FA, the chromosomes in your blood sample break and rearrange when mixed with the test chemicals. This doesn't happen in the cells of people who don't have FA.

Cytometric Flow Analysis

Cytometric flow analysis, or CFA, is done in a laboratory to see how chemicals affect your chromosomes as your cells grow and divide. Skin cells are used for this test. A technician mixes the skin cells with chemicals that can cause the chromosomes in those cells to act abnormally. If you have FA, your cells are much more sensitive to these chemicals. The chromosomes in your skin cells will break at a high rate as they go through the cycle in this test. This doesn't happen in the cells of people who don't have FA.

Mutation Screening

A mutation is an abnormality in a gene or genes. Geneticists and other specialists can examine genes in your cells, usually from a sample of your skin cells. With special equipment and laboratory processes, they can look for mutations in your genes that are linked to FA.

Diagnosing Different Age Groups

Before Birth (Prenatal)

If your family has a history of FA and you become pregnant, your doctor may want to test you or the fetus for FA before birth. Two tests can be used to diagnose FA in a developing fetus. They're done in a doctor's office or hospital.

• Amniocentesis. This test is done 15 to 18 weeks after a pregnant woman's last period. A doctor uses a needle to remove a small amount of fluid from the sac around the fetus. A technician tests chromosomes (chains of genes) from the fluid sample to see whether they have defective genes linked to FA.
• Chorionic villous sampling (CVS). This test is done 10 to 12 weeks after a pregnant woman's last period. A doctor inserts a thin tube through the vagina and cervix to the placenta (the temporary organ that connects the mother to the fetus). He or she removes a tissue sample from the placenta using gentle suction. The tissue sample is sent to a lab to be tested for genetic defects linked to FA. This test doesn't require anesthesia.

At Birth

Three out of 4 people who inherit FA are born with birth defects. If your baby is born with certain birth defects, your doctor may recommend genetic testing to confirm a diagnosis of FA.

Birth defects often linked to FA include:

• Missing, oddly shaped, or three or more thumbs
• Poorly developed or missing bones in the arms
• Hips, legs, hands, and toes that aren't fully or normally formed
• Curved spine
• Eyes, eyelids, and ears that aren't fully or normally shaped
• Skin discoloration
• Missing or misshapen kidneys
• Congenital heart defects
• Mental retardation
• Serious problems with the digestive system

Childhood and Later

You or your child may be born with FA, but not have birth defects. You may not be diagnosed with the disease until signs of bone marrow failure or cancer begin to show. This normally happens within the first 10 years of life.

Signs of bone marrow failure begin to show most often between the ages of 3 and 12, with 7 to 8 years as the most common ages. However, 10 percent of children with FA aren't diagnosed until after the age of 16.

If your bone marrow is failing, you may show signs of aplastic anemia. In aplastic anemia, your bone marrow slows down or stops producing all three types of blood cells: red and white blood cells and platelets. Aplastic anemia can be acquired after birth through exposure to chemicals, radiation, or medicines; or, it can be inherited, as with FA.

Doctors diagnose aplastic anemia using:

• A physical exam and family and medical history.
• A complete blood count (CBC) to check the number, size, and condition of your red blood cells. The CBC also checks the number of white blood cells and platelets.
• A reticulocyte count, which counts the number of new red blood cells in your blood to see whether your bone marrow is producing red blood cells at the proper rate.
• A bone marrow aspiration, in which a small amount of liquid bone marrow is removed and tested to see whether it's making enough blood cells.
• A bone marrow biopsy, in which a small amount of bone marrow tissue is removed and tested to see whether it's making enough blood cells.

For more information, see the Diseases and Conditions Index article on Aplastic Anemia.

If you or your child is diagnosed with aplastic anemia, your doctor will have to determine the cause. If your doctor suspects you have FA, he or she may order genetic testing.