FANCONI’S ANEMIA
What is Fanconi’s anemia?
Fanconi anemia is an inherited anemia that leads to bone marrow failure (Aplastic anemia). The bone marrow is the fluid within the bones that produces the cells in the blood. With failure of bone marrow production, the various cells in the blood are not formed and patients suffer from infections, spontaneous bleeds and low hemoglobin.
What is aplastic anemia?
Aplastic anemia is a condition that leads to bone marrow failure. Aplastic anemia can occur due to various causes such as drugs, infections, radiation, toxic chemicals and due to genetic disorders such as Fanconi anemia. Why patients with Fanconi anemia develop bone marrow failure is still not known.
What is Fanconi syndrome?
Fanconi syndrome is different from Fanconi Anemia. Fanconi syndrome leads to kidney problems and problems of acidification known as Renal Tubular Acidosis (RTA). Fanconi anemia is a blood disorder.
What are signs and symptoms of Fanconi’s anemia?
Patients with Fanconi’s anemia may have noticeable defects at birth and can be diagnosed early. Some patients are free from visible defects and are diagnosed when the bone marrow ultimately fails.
Common birth defects seen with Fanconi anemia are short stature, thumb and arms abnormality (missing, misshapen or extra thumb, incompletely developed or missing forearm bone). These conditions in medical terminology are described as absent, hypoplastic or bifid thumb and hypoplastic or absent radii respectively. In addition, parents may have skeletal abnormalities such as congenital hip abnormalities, spine abnormalities, scoliosis and rib defects.
Kidney defects in form of missing kidney, rotated or misshapen kidneys or fused kidneys can be seen.
Other abnormalities seen are skin pigmentation (café au lait spot), small head (microcephaly), small eyes (microphthalmia), learning disabilities, failure to gain weight, small reproductive organs (hypogonadism) in males and heart defects.
Most of the children present with anemia or spontaneous bleeding and blood tests reveal low red cells, white cells or platelets which may be due to bone marrow failure.
What is the diagnosis of Fanconi anemia?
A bone marrow examination reveals aplastic anemia. The most definitive test for Fanconi’s anemia is chromosome breakage test where the patient’s blood is collected and lymphocytes (type of white cells) from the blood are combined with chemical agents such as diepoxybutane. In the laboratory, the chromosomes within the Fanconi anemia cells break and rearrange whereas chromosomes in normal cells are stable at same dose.
What are the complications of Fanconi anemia?
Fanconi anemia patients have a higher incidence of cancer especially blood cancer (leukemia) than the general population. With onset of bone marrow failure, patients may succumb to infection (due to decrease in white cells), may have spontaneous bleeds (due to decrease in platelets) and have anemia (leading to decrease in oxygen supply to tissues).
If a child is diagnosed as Fanconi anemia, can his brothers and sisters also be affected??
Fanconi anemia is an inherited anemia. Both parents must be carriers of the Fanconi anemia gene for their child to be born with this disorder. If both parents carry the gene the chances are one in four (25%) that other children will also inherit the disease. This pattern of inheritance is known as “autosomal recessive” in medical terminology.
Thus, once a child is diagnosed as Fanconi anemia, other siblings in the family should also undergo the chromosomal breakage test even though they are normal otherwise.
Fanconi anemia can also be diagnosed before a child is born. The diagnosis can be done by performing a procedure called as chorionic villus sampling (CVS) at 10th – 12th week of pregnancy or by amniocentesis at 15th to 17th week of pregnancy and testing for chromosomal breakage.
At what age does aplastic anemia occur in Fanconi anemia?
No one can predict when marrow failure may occur. However most often it occurs in first decade of life though it has been reported to occur for first time even after the age of 40 years.
What is the treatment for Fanconi anemia?
The treatment for Fanconi anemia consists of :
- Bone marrow transplant
- Androgen therapy
- Synthetic growth factors (Hematopoietic growth factors)
- Gene therapy
Bone marrow transplant corrects problems related to bone marrow (anemia, low white count, low platelet count, leukemia). However patients may still suffer from problems related to other systems of the body.
Androgens are artificial male hormones that stimulate production of one or more types of blood cells for extended period of time. Androgens prolong the life of many Fanconi anemia patients but are not cure. Androgens can cause serious side effects such as liver disease and can have masculinizing effects which diminish or disappear with dose adjustments.
Hematopoietic growth factors such as GM-CSF, G-CSF increase the white cell count in patients with Fanconi anemia.
One of the Fanconi anemia genes has been isolated with the help of gene therapy; the corrected gene is introduced in the body with help of injection which supplies the missing protein needed in the Fanconi anemia patient’s body and blood system. However, gene therapy is still in the research phase.
Last updated on 01-12-2005
