What Is Aplastic Anemia
Aplastic anemia is a disorder in which the bone marrow fails to make blood cells. The bone marrow is the soft, inner part of bones where the 3 types of blood cells are made:
- red blood cells, which carry oxygen to the tissues from the lungs
- white blood cells, which fight infection
- platelets, which seal damaged blood vessels to prevent bleeding
These cells are made by blood-forming stem cells in the bone marrow. In aplastic anemia, the stem cells are damaged and there are very few of them. As a result, too few blood cells are produced. Rarely, just one of the cell lines, such as red cells, white cells, or platelets, is abnormal.
Aplastic anemia is not a type of cancer but may be associated with certain cancers (especially those affecting the bone marrow, such as leukemias) or cancer treatments. A small number of patients with aplastic anemia may develop leukemia.
There are 2 kinds of aplastic anemia, inherited and acquired. Acquired aplastic anemia is much more common than the inherited type.
Inherited Aplastic Anemia
The most common type of inherited aplastic anemia is called Fanconi Anemia.This is usually diagnosed in people when they are children or young adults. About half of patients with Fanconi anemia have other congenital problems such as growth retardation, small head size, absent thumbs, dark spots on the skin, and absence of 1 of the 2 bones in the forearm. There are several different gene abnormalities that can be inherited to cause Fanconi anemia. Some of these are linked to an increased risk for cancer. People with Fanconi anemia have a 50 times higher risk for other cancers, especially in the mouth and throat, esophagus, and leukemia.
The other kinds of inherited forms of aplastic anemia are much less common. One is called dyskeratosis congenita. People with this problem have abnormal skin pigmentation, abnormal finger nails, and white patches in their mouth (leukoplakia). This is very rare — only a few hundred patients are known worldwide. People with this problem also have a higher risk of developing cancers.
Another inherited cause of anemia is called the Diamond-Blackfan syndrome. In this situation, only red blood cell production is affected. A fourth disorder is the Shwachman-Diamond syndrome. Here, the major problem is poor production of white blood cells, although the other cell lines can occasionally be abnormal. In both of these, patients will often have other problems such as short stature and other bone abnormalities.
Acquired Aplastic Anemia
This usually occurs in adults, although children may also be affected. Most have no other abnormalities. But scientists have found that a few people with acquired aplastic anemia have an abnormality of genes responsible for keeping cell DNA intact. In most cases, the aplastic anemia is thought to be caused by a person’s reaction to some drug, chemical, or virus they were exposed to.