An acute infection of the respiratory tract that is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Based on currently available information, SARS-CoV-2 is thought to mainly spread from person to person through respiratory droplets. Typically, there is a two- to 14-day incubation period and infected persons can present with no symptoms or mild to severe fever, dry cough, fatigue, and difficulty breathing. Dysgeusia, anosmia, and gastrointestinal and flu-like symptoms have also been reported. Older adults and persons of any age who have serious underlying medical conditions may be of higher risk for severe illness, including secondary infections, respiratory failure, and multi-organ dysfunction. [from NCI]

Mantle cell lymphoma is a rare form of malignant non-Hodgkin lymphoma (see this term) affecting B lymphocytes in the lymph nodes in a region called the ``mantle zone''. [from ORDO]

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]

Thrombocythemia, or thrombocytosis, is a myeloproliferative disorder characterized by excessive platelet production resulting in increased numbers of circulating platelets. Thrombocythemia can be associated with thrombotic or hemorrhagic episodes and occasional leukemic transformation (summary by Wiestner et al., 1998). Genetic Heterogeneity of Thrombocythemia THCYT2 (601977) is caused by germline or somatic mutation in the THPO receptor gene (MPL; 159530) on chromosome 1p34, and THCYT3 (614521) is caused by germline or somatic mutation in the JAK2 gene (147796) on chromosome 9p. Somatic mutations in the TET2 (612839), ASXL1 (612990), SH2B3 (605093), and SF3B1 (605590) genes have also been found in cases of essential thrombocythemia. Somatic mutation in the CALR gene (109091) occurs in approximately 70% of essential thrombocythemia patients who lack JAK2 and MPL mutations (Klampfl et al., 2013; Nangalia et al., 2013). [from OMIM]

Diffuse large B-cell lymphoma is the most common subtype of non-Hodgkin lymphoma (NHL; see this term) in adults characterized by a median age of presentation in the sixth decade of life (but also rarely occurring in adolescents and children) with the initial presentation being single or multiple rapidly growing masses (that may or may not be painful) in nodal or extranodal sites (such as thyroid, skin, breast, gastrointestinal tract, testes, bone, or brain) and that can be accompanied by symptoms of fever, night sweats and weight loss. DLBCL has an aggressive disease course, with the elderly having a poorer prognosis than younger patients, and with relapses being common. [from ORDO]

A type of ALL characterized by elevated levels of B-cell lymphoblasts in the bone marrow and the blood. [from HPO]

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

MALT (mucosa-associated lymphoid tissue) lymphoma is a rare form of malignant non-Hodgkin lymphoma (see this term) that affects B cells and grows at the expense of lymphoid tissue associated with mucous membranes, but also occurs, more rarely, in lymph nodes. [from ORDO]

A type of T-cell lymphoma that is characterized by so-called hallmark cells with a pleomorphic appearance that express the CD30 antigen, are lobulated, and have indented nuclei. [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]

Chronic lymphocytic leukemia (CLL) is a common neoplasia of B lymphocytes in which these cells progressively accumulate in the bone marrow, blood, and lymphoid tissues. The clinical evolution of the disorder is heterogeneous, with some patients having indolent disease and others having aggressive disease and short survival (summary by Quesada et al., 2012). Genetic Heterogeneity of Susceptibility to Chronic Lymphocytic Leukemia Susceptibility loci have been mapped to chromosomes 11p11 (CLLS1; 609630) and 13q14 (CLLS2; 109543) by genomewide linkage analysis and translocation studies, respectively. Susceptibility mapping to chromosome 9q34 (CLLS3; 612557) is associated with downregulation of the DAPK1 gene (600831). Genomewide association studies have identified susceptibility loci on chromosomes 6p25.3 (CLLS4; 612558) and 11q24.1 (CLLS5; 612559). [from OMIM]

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

Multiple myeloma is a neoplastic plasma cell disorder characterized by clonal proliferation of malignant plasma cells in the bone marrow microenvironment, monoclonal protein in the blood or urine, and associated organ dysfunction (Palumbo and Anderson, 2011). [from OMIM]

A clonal expansion of myeloid blasts in the bone marrow, blood or other tissues. The classification of acute myeloid leukemias (AMLs) encompasses four major categories: 1) AML with recurrent genetic abnormalities; 2) AML with multilineage dysplasia; 3) Therapy-related AML; 4) AML not otherwise specified. The required bone marrow or peripheral blood blast percentage for the diagnosis of AML is 20% (WHO classification) [from NCBI]

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.\n\nInitially, 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.\n\nBecause 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.\n\nPrimary myelofibrosis is most commonly diagnosed in people aged 50 to 80 but can occur at any age. [from MedlinePlus Genetics]

An indolent B cell lymphoproliferative disorder of transformed follicular center B cells. Follicular lymphoma is characterized by diffuse lymphadenopathy, bone marrow involvement, splenomegaly and less commonly other extranodal sites of involvement. [from HPO]

A type of lymphoma characterized microscopically by the absence of multinucleated Reed-Sternberg cells. [from HPO]

Burkitt lymphoma is a rare, aggressive B-cell lymphoma that accounts for 30 to 50% of lymphomas in children but only 1 to 2% of lymphomas in adults (Harris and Horning, 2006). It results from chromosomal translocations that involve the MYC gene (190080) and either the lambda or the kappa light chain immunoglobulin genes (147220, 147200). Burkitt lymphoma is causally related to the Epstein-Barr virus (EBV), although the pathogenetic mechanisms are not clear. [from OMIM]