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What

Aplastic Anemia (AA) is a rare blood disorder characterized by failure of the bone marrow to produce adequate amounts of red blood cells, white blood cells, and platelets. Decreased amount of red blood cells (RBC) results in anemia and decreased ability of the blood to carry oxygen to the body. A low white blood cell count (WBC) makes the child susceptible to infection. Low levels of platelets cause decreased clot formation and bleeding. AA was first described in 1888.

Who

AA occurs in less than 10 people per million or approximately 1,000 people per year in United States. AA is more common in Asia, especially in Bangkok, Thailand and Japan. This may be due to increased exposure to toxic chemicals rather than genetic factors. Boys and girls are affected equally. AA can occur in children, but most commonly strikes people during their 20s and 60s. It is not contagious.

Signs and Symptoms

In contrast to leukemia, symptoms of AA develop gradually. Children develop pale complexion, rapid heart rate, shortness of breath, headache, dizziness, fatigue, possible leg swelling, gum bleeding, easy bruising, blood in the stool and urine, and red rash due to minor bleeding in the skin. In advanced disease, frequent and severe infections occur. Infections are commonly bacterial and fungal, i.e., pneumonia, oral thrush (a yeast infection of the mouth). Bacterial and fungal infections can also occur in the blood and urine of patients with severe AA, therefore, fever in these individuals is taken very seriously. The lymph nodes and liver are not enlarged, in contrast to leukemia. Children with congenital/inherited AA associated with syndromes may have abnormal facial features and skeletal abnormalities.

Possible Causes

The cause of AA is unknown. In 20% of cases it is thought to be congenital (present at birth) or inherited. It can be associated with syndromes such as Fanconi’s, Pearson, TAR, Shwachman-Diamond, and Diamond-Blackfan. In 80% of patients, AA develops later in life. The late form of AA may be autoimmune in nature, where the body’s immune system attacks the bone marrow. It is possible that some people are more susceptible to certain triggers, such as infections, drugs, and exposure to chemicals or radiation, so that in these people, exposure gives rise to AA. Possible infectious triggers include hepatitis viruses, Ebstein-Barr virus, HIV, Parvovirus, and tuberculosis. Drugs associated with AA include chloramphenicol, phenylbutazone, sulfa drugs, phenytoin, and gold. Exposure to heavy metals, benzene and occasionally pregnancy can also trigger AA. An important disease to distinguish from AA is leukemia. leukemia also causes decreased RBC, WBC and platelet levels. However leukemia differs from AA in that in leukemia the bone marrow cannot make blood cells because it is filled with cancer cells, while in AA, there are no cancer cells present.

Diagnosis

A complete blood count will reveal reduced numbers of blood cells. Other blood tests include testing for viruses and autoimmune diseases. A bone marrow biopsy is the most important test for diagnosing AA and excluding leukemia. This procedure involves inserting a needle into the pelvis bone to sample the bone marrow. The area is anesthetized to minimize pain prior to the procedure and younger children may need medicine to help them sleep so they remain still during the procedure. In AA, the bone marrow biopsy will show few cells and no evidence of cancer.

Treatment

Transfusions of RBC and platelets are often required when levels of these cells are very low. Drugs to increase WBC and RBC production called GCSF and EPO, respectively, may offer some benefit. Infections are treated with antibiotics and antifungal medication. If the child develops fever and the WBC is low, hospitalization will be required to test the blood for infection and start immediate intravenous antibiotics. bone marrow transplantation can be curative. During this procedure, stem cells (precursor blood cells) from the bone marrow of another individual are harvested and transfused into the AA patient, where they multiply and replace the patient’s deficient marrow. The patient’s bone marrow must match the donor’s bone marrow so that rejection does not occur. Siblings and other family members will be tested at the time of diagnosis to find a match. One third of patients find a relative who is a match. While, it is best to find a related donor, if a related donor is not found, unrelated donors can be tested for a match. To minimize the risk of rejection, excessive blood transfusions and transfusions from family members should be avoided prior to transplantation. In preparation for bone marrow transplantation, immunosuppressive medications are given. After bone marrow transplantation, immunosuppressive drugs are continued to prevent the transplanted cells from attacking the patient’s body (graft versus host disease). If a bone marrow match is not found, immunosuppressive medications can be used long-term. Patients can become transfusion independent, but the response is usually slow, requiring several months. A central venous catheter, a large intravenous line placed surgically, is often required to administer the medications. A hematologist (blood doctor) will be involved in the patient’s care. Patients should avoid activities with risk of trauma, as they are prone to bleeding. Meticulous hand washing, avoiding construction sites which may be a source of fungi, and avoiding exposure to sick people is recommended to minimize infections.

Prognosis

The major cause of illness and death in AA are infections and bleeding. Twenty percent of patients will have spontaneous recovery of the bone marrow. With immunosuppressive medication, close to 70% of patients respond well, however, they may relapse in the future and are at an increased risk of leukemia. bone marrow transplantation improves the 5 year survival rate to greater than 90%.

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

Aplastic Anemia and MDS International Foundation
Resources for patient assistance, advocacy, and support.

National Heart, Lung, Blood Institute
Contains information regarding clinical trials and new research.

National Marrow Donor Program
Nonprofit organization providing family support and advocacy. Manages the world's largest registry of volunteer stem cell donors and cord blood units.

Google Search for Aplastic Anemia

References and Sources

www.emedicine.com/med/topic162.htm www.umm.edu/blood/aneaplas.htm