Hemophilia refers to a group of inherited disorders that cause abnormal bleeding. The bleeding occurs because part of the blood -- called plasma -- has too little of a protein that helps blood clot.
Symptoms of hemophilia range from increased bleeding after trauma, injury, or surgery to sudden bleeding with no apparent cause. There are two types of hemophilia:
Hemophilia A -- also called classic hemophilia -- is most common and occurs in about 80% of people with hemophilia.
About 12,000 Americans develop different types of myelodysplastic syndrome each year. The risks of MDS increase with age. Factors that raise your risk of these problems include:
Cancer therapy. The use of certain chemotherapy drugs for cancer plays a role in many cases of later myelodysplastic syndrome. MDS may be more likely to occur after treatment for acute lymphocytic leukemia in childhood, Hodgkin's disease, or non-Hodgkin's lymphoma.
Cancer drugs linked to myelodysplastic syndrome include:
Some inherited conditions raise people's risk of having myelodysplastic syndrome. These include:
Fanconi anemia. In this condition, the bone marrow fails to make sufficient amounts of all three types of blood cells.
Shwachman-Diamond syndrome. This keeps the bone marrow from making enough white blood cells.
Severe congenital neutropenia. This condition is marked by insufficient neutrophils, which are a type of white blood cell.
Exposure to chemicals. You may be more likely to develop myelodysplastic syndrome if you're exposed to certain industrial chemicals over a long period of time. Smoking also raises people's risk of MDS.
Types of Myelodysplastic Syndrome
Several conditions are considered to be types of myelodysplastic syndrome. Factors that determine which type of MDS a person has include:
How many types of blood cells are affected. In some types of myelodysplastic syndrome, only one kind of blood cell is abnormal or low in number, such as red blood cells. In other kinds of MDS, more than one type of blood cell is involved.
The number of "blasts" in the bone marrow and blood. Blasts are blood cells that didn't mature fully and can't work like they should.
Whether the genetic material in the bone marrow is normal. In one type of MDS, the bone marrow is missing a portion of a chromosome.