MedGen

A myelodysplastic/myeloproliferative neoplasm which is characterized by persistent monocytosis, absence of a Philadelphia chromosome and BCR/ABL fusion gene, fewer than 20 percent blasts in the bone marrow and blood, myelodysplasia, and absence of PDGFRA or PDGFRB rearrangement. [from HPO]

A rare subtype of acute myeloid leukemia evolving from primitive megakaryoblasts. [from HPO]

A clonal (malignant) hematopoietic disorder with an acute onset, affecting the bone marrow and the peripheral blood. The malignant cells show minimal differentiation and are called blasts, either myeloid blasts (myeloblasts) or lymphoid blasts (lymphoblasts). [from HPO]

A disorder that results from a chromosomal abnormality. [from NCI]

Neoplasms located in the blood and blood-forming tissue (the bone marrow and lymphatic tissue). [from HPO]

Polycythemia is diagnosed if the red blood cell count, the hemoglobin level, and the red blood cell volume all exceed the upper limits of normal. [from HPO]

Proliferation (excess production) of hemopoietically active tissue or of tissue which has embryonic hemopoietic potential. [from HPO]

Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematologic stem cell disorders characterized by ineffective hematopoiesis resulting in low blood counts, most commonly anemia, and a risk of progression to acute myeloid leukemia (AML; 601626). Blood smears and bone marrow biopsies show dysplastic changes in myeloid cells, with abnormal proliferation and differentiation of 1 or more lineages (erythroid, myeloid, megakaryocytic). MDS can be subdivided into several categories based on morphologic characteristics, such as low-grade refractory anemia (RA) or high-grade refractory anemia with excess blasts (RAEB). Bone marrow biopsies of some patients show ringed sideroblasts (RARS), which reflects abnormal iron staining in mitochondria surrounding the nucleus of erythrocyte progenitors (summary by Delhommeau et al., 2009 and Papaemmanuil et al., 2011). [from OMIM]

A slowly progressing leukemia characterized by a clonal (malignant) proliferation of maturing and mature myeloid cells or mature lymphocytes. When the clonal cellular population is composed of myeloid cells, the process is called chronic myelogenous leukemia. When the clonal cellular population is composed of lymphocytes, it is classified as chronic lymphocytic leukemia, hairy cell leukemia, or T-cell large granular lymphocyte leukemia. [from HPO]

A rare subtype of acute myeloid leukemia characterized by clonal proliferation of poorly differentiated myeloid blasts in the bone marrow, blood or other tissues. It usually presents with anemia, thrombocytopenia and other nonspecific symptoms related to ineffective hematopoesis (fatigue, bleeding and bruising, recurrent infections, bone pain) and/or extramedullary site involvement (gingivitis, splenomegaly). Low remission rates are reported. [from ORDO]

A myeloproliferative disorder characterized by increased proliferation of the granulocytic cell line without the loss of their capacity to differentiate. [from HPO]

Replacement of bone marrow by fibrous tissue. [from HPO]

Polycythemia vera (PV), the most common form of primary polycythemia, is caused by somatic mutation in a single hematopoietic stem cell leading to clonal hematopoiesis. PV is a myeloproliferative disorder characterized predominantly by erythroid hyperplasia, but also by myeloid leukocytosis, thrombocytosis, and splenomegaly. Familial cases of PV are very rare and usually manifest in elderly patients (Cario, 2005). PV is distinct from the familial erythrocytoses (see, e.g., ECYT1, 133100), which are caused by inherited mutations resulting in hypersensitivity of erythroid progenitors to hormonal influences or increased levels of circulating hormones, namely erythropoietin (EPO; 133170) (Prchal, 2005). [from OMIM]

Primary myelofibrosis is a condition characterized by the buildup of scar tissue (fibrosis) in the bone marrow, the tissue that produces blood cells. Because of the fibrosis, the bone marrow is unable to make enough normal blood cells. The shortage of blood cells causes many of the signs and symptoms of primary myelofibrosis.

Initially, most people with primary myelofibrosis have no signs or symptoms. Eventually, fibrosis can lead to a reduction in the number of red blood cells, white blood cells, and platelets. A shortage of red blood cells (anemia) often causes extreme tiredness (fatigue) or shortness of breath. A loss of white blood cells can lead to an increased number of infections, and a reduction of platelets can cause easy bleeding or bruising.

Because blood cell formation (hematopoiesis) in the bone marrow is disrupted, other organs such as the spleen or liver may begin to produce blood cells. This process, called extramedullary hematopoiesis, often leads to an enlarged spleen (splenomegaly) or an enlarged liver (hepatomegaly). People with splenomegaly may feel pain or fullness in the abdomen, especially below the ribs on the left side. Other common signs and symptoms of primary myelofibrosis include fever, night sweats, and bone pain.

Primary myelofibrosis is most commonly diagnosed in people aged 50 to 80 but can occur at any age. [from MedlinePlus Genetics]

A rare unclassified acute myeloid leukemia characterized by an acute panmyeloid proliferation with blasts constituting more than 20% of cells in the bone marrow or peripheral blood, accompanied by fibrosis of the bone marrow. Patients typically present with acute onset of severe constitutional symptoms, bone pain, and pancytopenia. Splenomegaly is minimal or absent. The disease is rapidly progressive with poor therapy response. [from ORDO]

Familial erythrocytosis-7 (ECYT7) is characterized by an increased oxygen affinity of hemoglobin (Hb), which results in decreased delivery of oxygen into the peripheral tissues and compensatory polycythemia. Patients are generally asymptomatic, as compensatory polycythemia assures normal oxygen tissue delivery. Patients have normal red cell morphology (summary by Kralovics and Prchal, 2000). Wajcman and Galacteros (2005) noted that although high oxygen affinity hemoglobins are usually well tolerated in young patients, they can lead to thrombotic complications in older patients or when they are associated with another cause that increases thrombotic risk. Wajcman and Galacteros (2005) also noted that the effect of increased oxygen affinity of Hb caused by an alpha chain variant is usually milder than that caused by a beta chain variant (see 617980). [from OMIM]