Aplastic anemia is a rare but serious blood disorder that occurs when the body’s bone marrow cannot produce enough healthy blood cells to function properly.
Aplastic anemia can occur in both children and adults. Most cases of aplastic anemia are idiopathic, meaning the underlying cause is unknown. The blood disorder can have inherited (genetic) causes in a minority of cases.
What causes aplastic anemia?
Researchers believe most cases of idiopathic aplastic anemias result from the immune system mistakenly attacking the bone marrow, interrupting healthy blood cell production.
Other causes of aplastic anemia can include radiation, medications, infections (including hepatitis or HIV), or certain toxins.
In some cases, genetics do play a role, but hereditary aplastic anemia is rare. Children may inherit a disorder that predisposes them to develop aplastic anemia. These include but are not limited to:
- Fanconi Anemia
- Dyskeratosis Congenita / Telomere Biology Disorders
- Shwachman-Diamond syndrome
- GATA2 spectrum disorders
- SAMD9/SAMD9L disorders
Aplastic anemia symptoms occur because of the bone marrow’s failure to produce enough blood cells to support the body’s needs. Bone marrow is the spongey tissue inside of bones that contains hematopoietic stem cells —immature cells that eventually become red blood cells, white blood cells, or platelets. These are also called blood stem cells.
When healthy blood cell production is compromised, as is the case with aplastic anemia, the body experiences bone marrow failure, resulting in the following:
- Anemia, a condition marked by a decrease in hemoglobin — a protein in red blood cells responsible for transporting oxygen throughout the body. Symptoms of anemia include fatigue, shortness of breath, and pallor.
- Low white blood cell counts, which may increase susceptibility to infection.
- Low platelet count, which can lead to easy bleeding (this may include bleeding gums, nosebleeds, and blood in the stool) and bruising from a lack of blood-clotting platelets.
Symptoms may also resemble those of other blood disorders or medical problems.
What are treatment options?
Treatment for aplastic anemia varies depending on classification and other factors. Acquired aplastic anemia can be classified as moderate, severe or very severe, depending on stability of blood cell count and other symptoms.
Those with milder cases may only need to be monitored, but when more treatment is necessary, options may include:
- Immunosuppressive therapy, which uses medicines to suppress the immune system’s attack of bone marrow to allow the bone marrow to start producing blood cells normally again. The drugs used, anti-thymocyte globulin (ATG) and cyclosporine (CsA), may also have other effects that allow the bone marrow to make blood effectively again. It may take several months for the treatment to have an effect. During that time, children need frequent supportive care.
- Bone marrow transplant (stem cell transplant), a procedure which replaces the patient’s bone marrow with a donor’s healthy stem cells to stimulate new bone marrow growth and restore production of healthy blood cells.
- There are two types of stem cell transplants: allogenic and autologous. In an allogeneic transplant, cells are collected from a tissue-matched donor, usually a brother or sister or an unrelated donor, whose human leukocyte antigens (HLA) are a compatible match. An autologous transplant, by contrast, uses a person’s own stem cells. Allogenic transplants are used to treat aplastic anemia.
Before receiving the transplant, patients undergo immunosuppressive conditioning therapy, which includes chemotherapy and/or radiation. The goal of the conditioning therapy is to remove the diseased bone marrow cells to prepare for the new healthy ones. It also suppresses the immune system so that the body doesn’t reject the donor’s foreign stem cells. The transplant stem cells are infused into the blood through an IV.
It takes about four weeks for the new blood cells to grow, during which, the immune system is still weak, and the patient is highly susceptible to viral, bacterial, and fungal infections. Bone marrow failure disorders may create complications for transplants, so patients of all ages benefit from care at a highly experienced center.
Red blood cell and platelet transfusions may be required if a patient’s red blood cell count and platelet counts are very low. Antibiotics may also be used to help fight infections.
It can be necessary to treat underlying illnesses for the rare cases in which aplastic anemia is caused from a previous illness or disorder. Inherited causes of aplastic anemia are also treated differently.
Dana-Farber/Boston Children’s Cancer and Blood Disorders Center is currently collecting volunteered samples of blood and bone marrow from patients with aplastic anemia and other bone marrow failure syndromes to better understand genetic factors related to the diseases as well as patient outcomes.
There are several clinical trials open at Dana-Farber/Boston Children’s . Researchers are working to identify new drugs for treating pediatric patients with aplastic anemia.
- Eltrombopag, a drug that has shown promise in treating adults with the disease, is being studied in a clinical trial to investigate its effectiveness in treating children with aplastic anemia.
- A trial comparing two treatment options (unrelated donor stem cell transplant and immunosuppressive therapy) is currently enrolling patients.