A rare disorder in which the bone marrow does not make enough red blood cells. Signs and symptoms include fatigue, pale skin, breathing problems, dizziness, and headaches. Pure red cell aplasia mainly affects adults and may be caused by infection, kidney failure, an autoimmune disease (such as lupus or rheumatoid arthritis), pregnancy, a thymoma (tumor of the thymus gland), and certain types of cancer, including leukemia. It may also be caused by taking certain medicines. Pure red cell aplasia may also be inherited and seen in the first year of life, but this is very rare. Also called PRCA.