There are two types of rare blood disorders.

Myeloproliferative disorders originate when the bone marrow starts making too many red blood cells, platelets, or certain white blood cells. Together these disorders are referred to as myeloproliferative neoplasms (MPNs).

These diseases tend to worsen as the extra cells build up in the blood or bone marrow and over time, may cause bleeding, anemia, infection or fatigue. MPNs include

Lymphoproliferative disorders originate when the body produces too many lymphocytes (white blood cells) or when these cells behave abnormally. Lymphocytes are found in the lymphatic tissue in the lymph nodes, spleen, and thymus. These disorders are referred to as lymphoproliferative neoplasms (LPNs) and are usually diagnosed in people with compromised immune systems. LPNs include: