How Is Fanconi Anemia Diagnosed?

People who have Fanconi anemia (FA) are born with the disorder. 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 who have the disorder 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 and family histories 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 traits are passed from parents to children through genes.

Geneticists do genetic testing for FA. They also 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. An obstetrician is a doctor who specializes in providing care for pregnant women.

After your child is born, a pediatrician also can help find out whether your child has FA. A pediatrician is a doctor who specializes in treating children and teens.

A hematologist (blood disease specialist) also may help diagnose FA.

Family and Medical Histories

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 FA carriers, may not be aware of a family history of FA. Many parents may not know that FA can be passed from parents to children.

Knowing your family medical history can help your doctor diagnose whether you or your child has FA or another condition with similar symptoms.

If your doctor thinks 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
  • Any surgeries you’ve had related to the digestive system
  • Any personal or family history of immune disorders
  • Your appetite, eating habits, and any 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 recommend further testing.

Diagnostic Tests and Procedures

The signs and symptoms of 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 (labs). It shows whether your chromosomes (long chains of genes) break more easily than normal.

Skin cells sometimes are used for the test. Usually, though, a small amount of blood is taken from a vein in your arm using a needle. A technician combines some of the blood cells 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 lab. This test examines 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 the 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 during the test. This doesn't happen in the cells of people who don't have FA.

Mutation Screening

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

Diagnosing Different Age Groups

Before Birth (Prenatal)

If your family has a history of FA and you get pregnant, your doctor may want to test you or your fetus for FA.

Two tests can be used to diagnose FA in a developing fetus: amniocentesis (AM-ne-o-sen-TE-sis) and chorionic villus (ko-re-ON-ik VIL-us) sampling (CVS). Both tests are done in a doctor's office or hospital.

Amniocentesis 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 faulty genes associated with FA.

CVS 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 fetus to the mother).

The doctor removes a tissue sample from the placenta using gentle suction. The tissue sample is sent to a lab to be tested for genetic defects associated with FA.

At Birth

Three out of four 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.

For more information about these defects, go to “What Are the Signs and Symptoms of Fanconi Anemia?”

Childhood and Later

Some people who have FA are not born with birth defects. Doctors may not diagnose them with the disorder until signs of bone marrow failure or cancer occur. This usually happens within the first 10 years of life.

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

If your bone marrow is failing, you may have signs of aplastic anemia. FA is one type of aplastic anemia.

In aplastic anemia, your bone marrow stops making or doesn't make enough of all three types of blood cells: red blood cells, white blood cells, and platelets.

Aplastic anemia can be inherited or acquired after birth through exposure to chemicals, radiation, or medicines.

Doctors diagnose aplastic anemia using:

  • Family and medical histories and a physical exam.
  • complete blood count (CBC) to check the number, size, and condition of your red blood cells. The CBC also checks numbers of white blood cells and platelets.
  • A reticulocyte (re-TIK-u-lo-site) count. This test counts the number of new red blood cells in your blood to see whether your bone marrow is making red blood cells at the proper rate.
  • Bone marrow tests. For a bone marrow aspiration, a small amount of liquid bone marrow is removed and tested to see whether it's making enough blood cells. For a bone marrow biopsy, a small amount of bone marrow tissue is removed and tested to see whether it's making enough blood cells.

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



Source: National Heart, Lung, and Blood Institute, National Institutes of Health.