How is Fanconi Anaemia Diagnosed?
Fanconi anaemia (FA) is an inherited disease and therefore people who have FA are born with the disorder. They may or may not show signs or symptoms of FA 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.
Tests used to diagnose FA depend on the age of the person and symptoms. In all cases, medical and family histories are a significant part for the diagnosis of FA. However, because FA has many of the same signs and symptoms as other diseases, only genetic testing can confirm its diagnosis.
A haematologist (studies the nature, function and diseases of blood and of blood-forming organs) will diagnose FA. The haematologist must be the main doctor for the FA patient and all other specialists should report to him or her.
A geneticist is a doctor or scientist who studies how genes work in the body and how diseases and traits are passed from parents to children through genes.
Geneticists do genetic testing for FA. They also can provide counselling about how FA is inherited and the types of prenatal (before birth) testing used to diagnose it.
An obstetrician can detect birth defects prior to the child being born and can therefore determine whether the defect is linked to FA. An obstetrician is a doctor who specializes in providing care for pregnant women.
After your child is born, a paediatrician can also assist in finding out whether your child has FA. A paediatrician is a doctor who specializes in treating children and teens.
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 as this has never been a concern to them and the family. 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 anaemia,
- any surgeries you’ve had related to the digestive system,
- any personal or family history of immune disorders, and
- your appetite, eating habits, and any medicines you take.
If you know that your family has a history of FA, or if your answers to your doctor’s questions suggest a possible diagnosis of FA, your doctor should then recommend further testing.
Diagnostic Tests and Procedures
The signs and symptoms of FA aren’t unique to the disease. They are also linked to many other diseases and conditions, such as aplastic anaemia. For this reason, genetic testing is required to confirm a diagnosis of FA. Genetic tests for FA include the following.
Chromosome Breakage Test
A chromosome breakage test is the most common test for confirming FA in a patient. It is available only in special laboratories. It confirms more easy breakage of chromosomes (long chains of genes) than normal than that of a patient not having FA.
This test is done by taking a small blood sample from the potential FA patient and combining part of the blood’s white cells with a chemical, either mitomycin C or diepoxybutane. Breakage of chromosomes will be visible in a FA patient whereas the chromosomes will be more stable in a patient not having FA.
Cytometric Flow Analysis
Cytometric flow analysis, or CFA, is done in a laboratory. 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. You have FA if your cells are 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.
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 laboratory processes, they can look for gene mutations that are linked to FA.
Diagnosing different age groups
Before Birth (Prenatal)
If you are pregnant; it is strongly advised that your doctor test you and your fetus for FA if your family has a history of FA.
Amniocentesis and chorionic villus sampling (CVS) are two tests that can be preformed to diagnose FA in a developing fetus. 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. Chromosomes (chains of genes) are tested 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.
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 “Birth defects”
Childhood and Later
One out of four 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 often happens within the first 10 years of life.
Signs of bone marrow failure are most often set in motion between the ages of 3 and 12 years, with 7 to 8 years as the most common ages. However, 10 % of children who have FA are not diagnosed until after the age of 16 years..
If your bone marrow is failing, you have signs of aplastic anaemia. FA is one type of aplastic anaemia.
In aplastic anaemia, your bone marrow stops making or does not make enough of all three types of blood cells i.e. red blood cells, white blood cells, and platelets.
Aplastic anaemia can be inherited or obtained after birth through exposure to chemicals, radiation, or medicines.
Doctors diagnose aplastic anaemia using:
- Family and medical histories and a physical examination.
- A 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 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 anaemia, your doctor will want to find the cause. If your doctor suspects you have FA, he or she may recommend genetic testing.