Here are some terms for which you may need some additional reference or clarification. Click each letter for glossary terms.

  • A

    Acrocentric: Acrocentric chromosomes are those with the centromere very close to one end. The short arms (p) usually have small dot-like appendages on stalks, known as “chromosomal satillites”. In an acrocentric chromosome, the p arm contains repeating sequences, such as the nucleolar organizing regions (NORs). The acrocentric chromosomes in humans are chromosomes 13, 14, 15, 21, and 22.

    ALL (Acute Lymphoblastic Leukemia): A cancer of lymphocytes (the white blood cells) characterized by excess lymphoblasts. When the disease is malignant, immature lymphocytes continuously multiply and are overproduced in the bone marrow, causing normal cells to be outnumbered in this region.

    AML (Acute Myeloid Leukemia): A cancer of the myeloid line of blood cells, characterized by rapid growth of white blood cells accumulating in bone marrow and interfering with the production of normal blood cells in bone marrow.

    Amplification: An increase in gene copy number per cell; cytogenetic manifestations include double minutes and homogeneously staining regions.

    Anemia: Characterized by either a decrease in a normal level of red blood cells (RBC’s) or less than normal quantity of hemoglobin in blood.

    Apoptosis: A form of cell death in which a programmed sequence of events leads to the elimination of cells without releasing harmful substances into the surrounding area. Too little or too much apoptosis plays a role in a great many diseases. When programmed cell death does not work properly, cells that should be eliminated may remain and become immortal as in cancers such as leukemia.

    Array CGH: This method is advancement to CGH on metaphase chromosomes, as it provides significantly higher resolution. Defined DNA fragments are fixed in a matrix system (array CGH). There are bacterial artificial chromosome (BAC) arrays or even shorter single-stranded oligonucleotide arrays, or the more recent single-nucleotide polymorphism (SNP arrays). SNP arrays have multiple applications for assessing genomic imbalance, not reflected as copy number variations (CNVs).

    Atlas of Genetics and Cytogenetics in Oncology and Haematology: A peer reviewed on-line database which provides reviews on genes involved in cancer, leukemias, solid tumors, and cancer prone diseases.

    Autosome: All chromosomes, excluding sex chromosomes are classified as autosomes. Humans have a total of 22 pairs of autosomes.

  • B

    Band: The series of darkly and lightly stained stripes that appear across a chromosome when chemically treated and/or stained with certain dyes. Each chromosome has its own characteristic banding pattern that facilitates the specific identification of chromosomes or parts of chromosomes. The process used to achieve this result is called banding

    Banding: Spread metaphasic chromosomes are stained/banded, which allows their visualization and identification on a microscope. The most common banding method, which is referred to as GTG-banding, is done with trypsin and Giemsa stain. Other banding methods are Q-banding, R-banding, Acridine Orange R-banding, and some specialised banding methods such as C-bands, NOR-bands, BrdU-banding, DAPI-banding, SCE-banding, replication banding, and G11-banding.

    Basophils: Basophil granulocytes are the least common of the granulocytes representing about 0.01% to 0.03% of total white blood cells. The name derives from the fact that they are susceptible to staining by a base dye.

    Benign Tumor: A non-malignant tumor that remains localized and does not spread to other sites; generally amenable to local surgical removal and survival of the patient.

    Blast: Immature precursors of either lymphocytes (lymphoblasts), or granulocytes (myeloblasts), which do not normally appear in peripheral blood. They can be recognized by their large size and primitive nuclei. When present in the blood, they often signify acute forms of leukemia.

    Blood: Liquid tissue composed of seven different types of cells and cell fragments constitute blood; they are red blood cells (or erythrocytes), platelets (or thrombocytes), and five types of white blood cells (lymphocytes, monocytes, eosinophils, basophils, and neurophils).

    Bone Core: A biopsy in which a piece of bone and its associated marrow are removed for study.

    Bone Marrow Aspirate: A sample of bone marrow removed with a syringe and needle.

    Bone Marrow: It is the flexible tissue from the hollow interior of the bones. In adults, marrow in large bones produces new blood cells. It consists of 4% of body weight in adults.

    Breakpoint: A breakpoint is where one chromosome has split and the DNA is rearranged by the insertion of a piece from another chromosome or a different part of the same chromosome.

    Buffy Coat: The layer of cells in an anticoagulated blood sample that appears after density gradient centrifugation. It is located in between the plasma and the red blood cells that contains the lymphocytes, which can be used to initiate lymphocyte macro cultures.

  • C

    Carcinoma: Malignant growth of epithelial cells.

    Cell Culture: To achieve cell growth and division, leading to a good mitotic index for metaphase harvest. Cell culture methods vary with the tissue of origin, e.g. bone marrow, peripheral blood, solid tumors, and cell lines of various origins.

    Cell Cycle Synchronization: The manipulation of the cells so they are all brought to the same phase of the cell cycle at the same time.

    Cell Division: The mechanism by which cells multiply during the growth of tissues or organs. The type of cell division involved in the growth of the body is known as mitosis (M phase of the cell cycle), and the type of cell division that produces sperm in the testis or ova in the ovary is known as meiosis.

    Centromere: The constricted part of the chromosome separating the short arm (p) from the long arm (q). It is the attachment point for the mitotic spindle during cell division.

    Chromatid: Two visible subunits of a metaphase chromosome, each composed of a DNA molecule.

    Chromosomal Satellite (also called satellite II): It is a small mass of chromatin attached to the short arm of each chromatid of human acrocentric chromosomes by a relatively uncondensed stalk or secondary constriction. They do not always stain darkly by G-band and may be difficult to see. Satellites on different chromosomes are often attracted to one another, causing the acrocentric chromosomes to be in satellite association. Not to be confused with satellite DNA (satellite I).

    Chromosome Arm: In metacentric, submetacentric and acrocentric chromosomes, chromosome body is divided into two halves by the centromere. The shorter part is called the short arm (p; petite) and the longer part is referred to as the long arm (q).

    Chromosome Number: In humans, the chromosome number is 23 pairs for a total of 46. Half of the chromosomes, 23 (22 autosomes and X) are inherited from the mother and half (22 autosomes and X or Y) from the father.

    Chromosome: Means “colored body” in Greek. Thread-like structures composed of DNA containing all genetic information from both parents within the nucleus of most cells of the body. Different kinds of organisms have different modal numbers.

    cIgFISH: A combination of immunolabeling of cell cytoplasm immunoglobulin light chain (l or k) and FISH. It is used in the diagnosis and prognosis of MM which is frequently accompanied by different chromosomal abnormalities such as t(4;14)(p16;q32), t(14;16)(q32;q23), and deletion of chromosome 13. However, they are difficult to be determined by conventional cytogenetics due to low mitotic index of plasmacytoma cells. Therefore, abnormalities that result in poor survival of afflicted patients are usually determined by interfase FISH. However, bone marrow infiltration by plasmocytoma cells can vary considerably depending on type and progress of multiple myeloma. Due to inability of FISH to distinguish between plasmocytoma and the rest of bone marrow cells, the results can be well below the correct value. The immunolabeling of the plasma cells in cIg FISH determines the cell of interest for FISH scoring.

    CLL (Chronic Lymphocytic Leukemia): A cancer of white blood cells, in which mature lymphocytes function abnormally and cause disease.

    Clonal: In clinical cytogenetics, the presence of two or more identical trisomic or structurally rearraged cells, or three or more identical monosomic cells.

    Clone: A cell population derived from a single progenitor cell. It must have at least two cells in which the abnormality is chromosomal gain or structural change. For a chromosomal loss, the clone should have at least three cells with the same abnormality. Subclones evolve as cytogenetically related changes from a primary clone, as the tumor proliferates. A stemline (sl) is the most basic or primary clone of a tumor cell population; other subclones deriving from stemlines are called sidelines. Mainline is the most common of the largest subclone of a tumor cell population. It does not necessarily imply the primary or basic cell line in tumors of progression.

    CML (Chronic Myeloid Leukemia): Cancer of the white blood cells in which rapid growth of white blood cells (WBC’s) leads to chronic leukemia, one subtype being chronic lymphoblastic leukemia (CLL) and the other being chronic myeloid leukemia (CML) affecting abnormal proliferation of WBC’s called granulocytes.

    Colcemid: The brand name of synthetic colchicine.

    Colchicine: An alkaloid derived from members of the plant genus Colchicum that irreversibly binds tubulin and prevents the chromosomes of mitotic cells from entering anaphase.

    Complete Medium: A basal culture medium supplemented with nutrients to enhance the growth of cells.

    Composite Karyotype: When there is great heterogeneity in the tumor cell population with multiple cell clones. At times, the changes in subclones are so numerous that a composite karyotype is the only option. It contains all clonally occurring abnormalities so that only a range of chromosome numbers can be given.

    Conditioned Medium: Medium containing growth factors secreted by actively dividing cells.

    Copy Number Analysis (CNA): The process of analyzing data produced by a test for DNA copy number variation in patient’s sample. CNA detects chromosomal copy number variation that may cause or increase risks of various critical disorders.

    Copy Number Variation (CNV): Copy-number differences are found in a segment of DNA by comparison of two or more genomes.

    Couterstain: A second stain or dye that is of a contrasting color to a first specific stain or dye used to identify a particular target. Counterstains can be used to stain cells, nuclei or DNA, depending on the assay. For FISH, counterstains consisting of fluorophores are used to stain DNA, a contrasting color to distinguish the background DNA from the specifically labeled probe hybridized to the target DNA. Commonly used counterstains for FISH include DAPI, Torpo3, and propidium iodide.

    Cytogenetics: The study of the number, structure, behavior during cell division and effects of chromosomes and their abnormalities on the genotype and phenotype of the individual.

    Cytopenias: A deficiency of any type of blood cells.

  • D

    DAPI: 4,6 diamino-2-phenylindole, a DNA dye which fluoresces a blue color when exposed to ultraviolet light (UV) and is used to stain the DNA in FISH assays. DAPI is a good counterstain for FISH when using red, green and gold labeled chromosome painting probes.

    Deletion: Loss of a whole chromosome or part of a chromosome leading to loss of genes. The term usually refers to loss of part of a chromosome (e.g. a partial deletion). A terminal deletion refers to breakage and loss off the end of a chromosome; interstitial deletion corresponds to the loss of genomic material within a chromosome.

    Denaturation: Paired up complimentary bases along the duplex nucleic acid strands are separated into single strands. The breakup of chemical bonds involved in complementary base pairing is usually produced by heat (although chemical means can be used). The genomic DNA of the specimen and FISH probes are denatured at a high temperature (usually 75-80°) before hybridization.

    Diandry: The presence in a triploid of two paternal and one maternal haploid set of chromosomes.

    Dicentric: A chromosome that possesses two centromeres, either from the same chromosome or from non-homologous chromosomes.

    Digynic: The presence in a triploid of two maternal and one paternal haploid set of chromosomes.

    Diploidy: A cell with a normal chromosome number including two sets of parental chromosomes (23 from each parent).

    Dispermy: Fertilization of a single oocyte by two separate sperm. It is the most common cause of triploidy.

    DNA (Deoxyribonucleic Acid): Long double-stranded molecule found in the nucleus of cells and packaged into chromosomes. DNA contains the genetic instructions used in the development and functioning of organisms.

    Double Minutes (DMin): Paired acentric chromatin bodies that represent cytogenetic manifestation of gene amplification.

    Duplication: Phenomena resulting in an extra (abnormal) copy of a genomic duplicated material.

  • E

    Eosinophils: Eosinophils are granulocytes that develop during hematopoiesis in the bone marrow before migrating into the blood. They constitute the immune system component of white blood cells responsible for combating infections. Together with mast cells, they control the mechanism associated with allergy and asthma. The name “eosinophil” is derived from the fact that they are eosinophilic due to their affinity to coal and tar dyes.

    Euchromatin: Chromosomal DNA which is genetically active and pale staining with G- and C- banding. Euchromatin is relatively rich in GC base pairs. During interphase it is uncoiled and transcriptionally active whereas heterochromatin is condensed and inactive.

  • F

    Familial Disease: Tendency for a disease to occur in more members of a family than expected by chance alone. For example, Down syndrome which has occurred more than once within a family because of an inherited chromosome translocation, can be said to be a familial disease.

    FISH (Fluorescence in situ hybridization): Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique that permits physical visualization and mapping of specific genes or loci of interest on metaphasic chromosome or interphase nucleus. It is achieved by hybridizing a fluorescently-labeled DNA sequence (DNA-FISH Probe) that is complementary to the DNA sequence of interest. The specimen (fixed cell preparations from blood, bone marrow, or sections of tissues where nuclei are morphologically preserved) containing the target DNA is prepared according to standard histologic and cytogenetic methods. The technique was developed about 20 years ago, to permit physical mapping of genes on the human genome and it appeared quickly as a versatile tool to permit the detection of specific chromosomal aberrations in human disease, such as cancer. In a clinical setting, FISH technique is considered as an adjunct assay to classical cytogenetics (karyotyping) where the whole complement of metaphase chromosomes is examined for aberrations. FISH only allows the detection of aberrations specific to each DNA- FISH Probe or combination there-of, however, the assay does not rely on growth of the cells as does karyotyping. In the clinical setting, FISH assays are utilized in various aspects of disease management and with respect to cancer includes diagnosis, prognosis, and minimal residual disease detection. The use of FISH in each of these areas is disease-specific, and the aberration detected can represent either numeric changes in genetic material (gain, amplification, or deletion of parts of or whole chromosomes), or rearrangements and translocations of genetic material (balanced or unbalanced, inter- or intra-chromosomal).

    Fixative: A solution used to preserve cells for microscopic studies. Fixative is used to stop the exposure to hypotonic solution and alter the cytoplasmic membrane.

    Flow Cytometry: A technique used to count and separate cells and chromosomes by suspending them in a stream of fluid and passing them through electronic detection. This technique is routinely used with blood cancers.

    Fluorescence Microscopy: Fluorescence Microscopy has become an essential tool in biology and the biomedical sciences, as well as in materials science due to attributes that are not readily available in other contrast modes with traditional optical microscopy. The application of an array of fluorochromes has made it possible to identify cells and sub-microscopic cellular components with a high degree of specificity amid non-fluorescing material. In fact, the fluorescence microscope is capable of revealing the presence of a single molecule. Through the use of multiple fluorescence labeling, different probes can simultaneously identify several target molecules simultaneously. Although the fluorescence microscope cannot provide spatial resolution below the diffraction limit of specific specimen features, the detection of fluorescing molecules below such limits is readily achieved.

  • G

    G1 Phase: The phase of the cell cycle between the end of mitosis (M phase) and the beginning of DNA synthesis (S phase).

    G2 Phase: The phase of the cell cycle between the end of the DNA synthesis (S phase) and the initiation of mitosis (M phase).

    Gender Mismatched Bone Marrow Transplantation: In hematopoietic malignancies, monitoring of residual disease is done by FISH testing of donor cells (e.g. XY cells) in host tissues (e.g. XX cells).

    Gene Rearrangement: A change in the gene structure or molecular arrangement within the chromosome. Hematopoietic somatic cells destined to become T-cells or B-cells rearrange their T-cell receptor genes and immunoglobulin genes in a fashion that allows for the generation of receptor diversity. Gene rearrangement also refers to the rearrangement in genes that occurs as a result of chromosomal translocation or similar structural changes. For example, ABL/BCR rearrangement occurs as a result of a translocation between two chromosomes 9 and 22. This translocation is annotated t(9;22).

    Gene: Sequence coding a protein or a RNA product. A gene includes also regulatory regions that can be localized upstream or downstream of the coding sequence.

    Genome: Refers to the total genetic material in the chromosomes from a cell of an organism.

    Genetic Disorder: Disease resulting from the alteration of the genome of an individual. The genetic abnormality can caused by small mutation in a single gene by the addition or deletion of an entire chromosome or set of chromosomes.

    Giemsa: A complex dye mixture used for solid staining metaphase chromosomes, or as a reagent in chromosomal banding protocols.

    Growth Factors: Culture additives that enhance cell proliferation.

    GTG-band: The common banding produced with Trypsin and Giemsa stain and used to routinely identify chromosomes.

  • H

    Haploid: The chromosome number (23) found in the parental gamete; half the diploid number.

    Hematological Malignancy: A cancer of the blood or bone marrow, such as leukemia or lymphoma.

    Hemopoiesis: The production and maturation of blood cells, usually in bone marrow, sometimes in spleen or other organs. Cells and tissues that produce blood cells are known as hemopoetic.

    Heterochromatin: Chromosomal material which is condensed and genetically inactive during interphase. It consists of repetitive DNA sequences that are relatively rich in AT base pairs and is late replicating in the cell cycle. In metaphase chromosomes, it is dark staining with G- and C- banding.

    Histones: DNA proteins associated with whose function it is to ensure the condensation of a chromosome.

    Histopathology: Refers to the examination of a tissue specimen under a microscope in order to detect the manifestation of a disease.

    Hodgkin’s Lymphoma: A rare lymphoma or cancer of the lymphatic system, originating from white blood cells (lymphocytes).

    Homogeneously Staining Regions (HSR): Chromosomal regions that stain uniformly and represent amplified copies of a DNA segment.

    Homologous Chromosomes: A pair of chromosomes of the same length, centromere position and staining pattern, and shape. Each chromosome in a pair is inherited from each parent.

    Hybridization: Base pairing of two single strands of DNA or RNA by hydrogen bonding between complimentary nucleotides.

    Hypotonic Solution: A solution having a lower ionic concentration relative to another solution. A cell placed in a hypotonic solution will swell and possibly burst.

  • I

    Ideogram: A schematic drawing of chromosomes when stained with Giemsa stain. Particularly distinct regions called light and dark bands, which give each chromosome a unique appearance, are given specific nomenclature by ISCN.

    Immunophenotyping: The analysis of a heterogeneous population of cells using antibody markers to detect the proteins expressed in each cell.

    In Situ Hybridization (ISH): The base pairing of a nucleotide sequence to metaphase chromosomes and/or interphase nuclei.

    Indirect Labeling: A process by which a molecule is labeled (e.g. with fluorescence) requiring a secondary reporter signal for detection. It requires a second reporter signal for detection.

    Insertion: The integration of a piece of DNA (e.g., a region from one chromosome) into a chromosome in a region where is does not normally belong.

    Interphase: A stage of the cell cycle between two mitoses, comprising G1, S, and G2. The nuclear DNA is not highly condensed and individual chromosomes cannot be distinguished.

    Inversion: The breakage of a chromosome in two places followed by a 180-degree flip of the segment between the breaks. There is no loss or gain of material, but the sequence of the inverted segment is reversed.

    ISCN: The International System of Cytogenetic Nomenclature provides the terminology used to describe chromosome constitutions.

    Isochromosome: A mirror-image chromosome in which one arm is duplicated and the other is absent; the duplicated arms are united at the centromere.

  • J

    No Terms Listed.

  • K

    Karyotype: The arrangement of the chromosomes of a single cell in the standard classification of descending size, appropriate centromere location and banding pattern. A normal Karyotype includes 22 pairs of autosomes and one pair of heterochromosomes (XX or XY).

    Kinetochore: A protein structure at the centromere to which the spindle fibers attach during cell division.

  • L

    Leukemia: Any of several acute or chronic forms of neoplastic disease of the bone marrow in which unrestrained proliferation of white blood cells occurs. This is often accompanied by anemia, impaired blood clotting, or enlargement of lymph nodes, spleen or liver.

    Leukocyte: White blood cell of any type.

    Leukocytosis: An increase in the number of leukocytes above the normal range.

    Leukopenia: A decrease in the number of leukocytes below the normal range.

    Low Copy Repeat (LCR): These are highly homologous, chromosome-specific repeated DNA sequences.

    Lymphocyte: A type of white blood cell. Under the microscope, lymphocytes consist of large granular natural killer cells (NKC’s). Small lymphocytes consist of T (Thymus) and B (Bone) cells.

    Lymphocytopenia: An abnormally decreased number of lymphocytes in the blood. This is the opposite state of Lymphocytosis.

    Lymphocytosis: An increased proportion of lymphocytes in blood shown by complete blood cell count.

    Lymphoma: Cancer affecting the lymphatic system, usually lymphocytic, including the spleen and lymph nodes. Lymphomas are divided into Hodgkin’s disease or Non-Hodgkin’s Lymphoma.

  • M

    Macroculture: A culture method that uses the buffy coat for blood or bone marrow culture initiation and requires a relatively larger volume of blood or bone marrow.

    Malignant Tumor: A tumor with properties of invasion and metastasis which can cause death.

    Marker Chromosome: A chromosome, usually small, of unknown origin and unidentifiable from its G-banding pattern.

    Mast Cell: A cell type best known for its role in allergic response and anaphylaxis. Mast cells also play a protective role in defense against pathogens and wound healing.

    Megakaryocytes: A bone marrow cell responsible for the production of blood thrombocytes (platelets), essential for blood clotting.

    Meiosis: See cell division.

    Metacentric: A subdivision of chromosomes which have centromeres in the middle and the p and q arms are of equal length.

    Metaphase Harvest: A process of isolating cells in the metaphase of mitosis involving three major steps: 1.) blocking cell division 2.) hypotonic treatment of cells; and 3.) fixation. Metaphases of lymphocytes are usually harvested when the cells are subconfluent. Chemicals, such as colcemide, are added to the culture to block mitotic spindle formation, arresting cell division at metaphase. Cells are then treated with a hypotonic solution that swells the cell. Finally a fixative solution (such as 3:1 methanol:acetic acid) is added to the cell suspension to preserve the cells in their swollen state and to remove water, thus hardening the biologic material. The fixative also removes lipids and alters/denatures proteins, making the cell membrane very fragile, which is important for subsequent chromosome spreading on microscope slides.

    Metaphase: Stage of the cell cycle in mitosis or meiosis when the chromosomes have reached their maximal condensation and individual chromosomes can be identified. Metaphase spread refers to the view of a cell’s chromosomes at the metaphase stage spread on a slide.

    Microculture: A culture method that uses whole blood or bone marrow for culture initiation and so requires less blood or bone marrow volume.

    Mitotic Index: The percentage of cells in mitosis in a total cell population.

    Mitogens: Chemical compounds used to initiate cell division in a tissue, when spontaneous cell division is low or absent. Specific mitogens are used to divide T and B cells.

    Mitosis: See cell division.

    Modal Number: The chromosome count that is characteristic of cells from a particular species or cell line. For instance, the normal human modal number is 46.

    Modified Carnoy’s Fixative: A 3:1 solution of absolute methanol and glacial acetic acid. It is used as a fixative in cytogenetic culture.

    Molecular Cytogenetics: A field involving a combination of standard cytogenetics and molecular biology techiques. Generally, it involves applying FISH techniques to metaphase chromosomes or interphase cells.

    Monocyte: A type of white blood cell that forms part of the human body’s immune system. Its roles include replenishing macrophages and dendritic cells under normal state response to inflammation signals. They move fast to the site of infection and differentiate into macrophages and dendritic cells to elicit an immune response.

    Monolayer Culture: Single layer of cells attached to substrate.

    Monosomy: A single copy of a chromosome rather than a pair (disomy).

    Mosaicism: The co-existence of genetically different cells within the same individual or tissue. (e.g. a mixture of both normal cells and cells with a chromosome abnormality, or with different alleles.)

    Multiple Chromosome Rearrangement: Complex chromosome aberration involving three or more chromosomes.

    MDS (Myelodysplastic Syndrome): Improperly formed, non-functioning cells in the hematopoietic marrow.

    Myeloid Cells: White blood cells, specifically granulocytes and monocytes.

  • N

    NCCN Clinical Practice Guidelines in Oncology: Guidelines which are widely recognized and used as the standard for clinical policy in oncology by clinicans and payors. (

    Neutropenia: An abnormally low number of neutrophils (a type of white blood cell) in the blood.

    Neutrophil: Neutrophil granulocytes are the most abundant white blood cells (WBC’s) in mammals and form an essential part of the immune system. They form part of the polymorphonuclear cell family (PMN) together with basophils and eosinophils.

    NHL (Non-Hodgkin’s Disease): A cancer of lymphocytes that spreads more easily to other parts of the body. It has about ten subtypes and twenty different disease entities, being of low grade or high grade lymphomas. Some of the NHL’s include mantle cell lymphoma (MCL), follicular cell lymphoma (FCL), Burkitt’s lymphoma (BL), and diffuse large B-cell lymphoma (DLBCL).

    Nondisjunction: The failure of homologous chromosomes to segregate into each daughter cell during the mitotic or meiotic anaphase. Instead, the pair remains attached, and both chromosomes move into the same daughter cell, resulting in deficiency in one cell and excess in the other.

    Nucleosome: The primary structural unit of chromatin consisting of DNA wrapped around a core of histones.

    Oncogene: A dominant-acting gene that has transforming ability, (i.e., causing a cell to grow in an uncontrolled manner) and is responsible for tumor development. Oncogenes play a role in the cell cycle. Mutation, over-expression, or amplification of oncogenes in somatic cells can lead to cellular transformation.

  • O

    Oncogene: A dominant-acting gene that has transforming ability, (i.e., causing a cell to grow in an uncontrolled manner) and is responsible for tumor development. Oncogenes play a role in the cell cycle. Mutation, over-expression, or amplification of oncogenes in somatic cells can lead to cellular transformation.

  • P

    Pancytopenia: A condition in which there is a decrease of white blood cells and platelets.

    PHA (Phytohemagglutinin): The most specific mitogen for T cell lymphocytes. Some B cell specific mitogens include TPA, PWM, LPS, Protein A, IL-6, EBV, DPS-30, IL-4 and IL-2. Most B cell mitogens divide both B and T cells.

    Plasma Cell: White blood cells which produce large volumes of antibodies. They are transported by the blood plasma and lymphatic system. Originally in bone marrow, they migrate as B cells before terminal differentiation into plasma cells in lymph nodes.

    Platelets: Platelets or thrombocytes are small irregularly shaped anuclear fragments, derived from the megakaryocytes. They function in homeostasis to form blood clots.

    Pluripotent Cell: Cell that is capable of becoming any type of differentiated cell.

    Polymorphism: A variation in the DNA or chromosome appearance that is too common to attribute to new mutation, and is thus considered to be normal. These clinically insignificant “normal variants” are passed on within families without causing any problems in development. A polymorphism must have a frequency of at least 1% in the population.

    Polyploidy: Refers to a chromosome number that is more than double the haploid number (i.e. n=23, 2n=46 in humans, but polyploid organisms cells are 3n, 4n, etc.).

    Probe: A small segment of DNA of known origin, designed to recognize complementary DNA on specific parts of chromosomes (targets). The probe can be labeled with a fluorescent or hapten molecules, used to confirm the presence or absence of the target material.

    Proteases: An enzyme that breaks down proteins.

    Proto-oncogene: A normal gene that can become an oncogene due to mutations or increased expression. The resultant protein may be termed an oncoprotein. Proto-oncogenes code for proteins that help to regulate cell growth and differentiation. They are often involved in signal transduction and execution of mitogenic signals, usually through their protein products. Upon activation, a proto-oncogene (or its product) becomes a tumor-inducing agent, an oncogene. Examples of proto-oncogenes include RAS, WNT, MYC, ERK, and TRK.

  • Q

    No Entries Listed.

  • R

    Reciprocal Translocation: The breakage and exchange of material between two chromosomes without any gain or loss of genetic material. A reciprocal translocation is described as “balanced” to indicate the genetic material is conserved. When translocated chromosomes are passed on to offspring in a way which results in gain or loss of material, the translocation is described in the offspring as “unbalanced”.

    Relapsed Diseases: Incomplete response to treatment of cancers, resulting in a recurrence of the disease.

    Remission: Refers to absence of disease. At times, total remission occurs, but relapse can occur even after years of therapy.

    Repetitive DNA: DNA sequences that are present in multiple copies in the genome.

    Residual Disease/Minimal Residual Disease (MRD): When some cancer cells remain during or after attempted therapy.

    Restriction of Chromosome Condensation: Prevention of chromosome shortening by adding a substance to the culture that intercalates in the DNA strands as they proceed through the early stages of mitosis.

    Ring Chromosome: A chromosome, which has broken at each end, lost the terminal segments, curled around and rejoined to form a ring shape. Formation of a ring may result in the loss or deletion of the terminal segments.

    Robertsonian Translocation: A type of translocation exclusive to the acrocentric chromosomes (chromosome 13, 14, 15, 21, 22), in which two chromosomes join at or near their centromeres. This is effectively a fusion between two whole chromosomes rather than an exchange of material as in reciprocal translocation.

  • S

    S Phase: The phase of the cell cycle during which DNA synthesis takes place.

    Satellite DNA: DNA containing many tandem repeats of a short basic repeating unit. There are different types of such tandem repeats throughout the genome. Satellite DNA derives its name from the fact that historically tandem repeat families could be purified by density gradient centrifugation from the rest of the genome as “satellite” fractions of DNA. Not to be confused with the term chromosomal satellite, which is a small mass of chromatin at the end of the short arm of each chromatid of an acrocentric chromosome.

    Satellite I: Refers to satellite DNA.

    Satellite II: Refers to chromosomal satellite.

    Satellite III: Heterochromatic DNA specific to chromosome Y.

    Secondary Constriction: A negatively staining heterochromatic region of a chromosome.

    Sex Chromosome: One of the two chromosomes that specify an organism’s genetic sex. Humans have two sex chromosomes, X and Y. Normal females possess two X chromosomes and normal males one X and one Y.

    SKY (Spectral Karyotyping)/M-FISH (Multiplex FISH): A FISH technique which uses complex combinatorial probes and sophisticated image analysis software to produce 24 discrete colors for viewing individually colored chromosomes and thereby identity structural aberrations often associated with cancers and other disease states.

    Solid Tumor: Any non-hematological malignancy.

    Somatic Cell Hybrids: Also called hybrid cell or hybrid cell line. A cell formed by fusion of two cells of different origin, in which the two nuclei have merged into one. Common somatic cell hybrids are from human and hamster cell origins.

    Spicule: Microscopic fragment of bone found in marrow but not in blood.

    Stem Cell: Undifferentiated cell that may differentiate into many cell types.

    Stroma: Connective tissue cells in an organ or tumor. These may be fibroblasts, blood vessels or normal cells that provide a supportive matrix to the organ or tumor.

    Submetacentric: Chromosomes with centromeres which are not centrally placed and whose arms are not of equal length.

  • T

    Telomerase: An enzyme that catalyzes replication of the ends of the chromosomes (telomeres) during cell division.

    Telomere: The terminal segment of a chromosome arm.

    Tetraploidy: Refers to a cell having four haploid sets (4n) of parental chromosomes, giving a total chromosome count in humans, of 92.

    Tetrasomy: The presence of four copies of a particular chromosome instead of two.

    Thrombocytopenia: An abnormal decrease in the level of blood cells and platelets, which results in the forming of blood clots.

    Thrombocytosis: The presence of high platelet counts in the blood, and may be a primary or reactive condition.

    Translocation: The fusion or exchange of material between chromosomes. When there is no gain or loss of material, the translocation is said to be balanced. When there is gain or loss, resulting in trisomy or monosomy for a particular chromosome segment, it is said to be unbalanced.

    Triploidy: The presence in a cell of three haploid sets (three sets of 23 chromosomes in humans) of parental chromosomes, giving a total chromosome count of 69.

    Trisomy: The presence of three copies of a particular chromosome, i.e. trisomy 21. Three copies of part of a chromosome is partial trisomy.

    Tumor Suppressor Gene (TSG): A normal gene involved in the regulation of cell growth. A recessive mutation in a TSG can lead to tumor development.

  • U

    Uniparental Disomy: Both members of a chromosome pair are contributed by one parent rather than one from each parent.

    UroVysion™ FISH: A FISH technique employed together with standard diagnostic protocol for initial diagnosis of urothelial cancer with hematuria and for monitoring recurrence/relapse in previous patients with bladder carcinoma. UroVysion™ FISH detects aneuploidy status of chromosomes 3, 7, and 17 and the deletion of chromosomes 9p21 locus from patients’ urine samples. The presence of these chromosomal abnormalities is indicative of bladder cancer. This test is a trademark of Abbott Molecular and is approved by the FDA.

  • V

    Virtual Karyotype: The entire genome is scanned for copy number changes resulting in a virtual karyotype. Virtual karyotypes are generated using arrays made up of millions of probes and computational tools used to recreate the genome in silico.

  • W

    White Blood Cells: WBC’s or leukocytes are cells of the immune system which protect against foreign bodies and infectious disease. Five different kinds of leukocytes consist of lymphocytes, monocytes, eosinophils, basophils, and neurophils.

  • X

    No Entries Listed

  • Y

    No Entries Listed.

  • Z

    Zygote: The single cell with 46 chromosomes in humans resulting from the fertilization of an ovum (23 chromosomes) by a sperm (23 chromosomes). Through cell division (mitosis), the zygote develops into a multicellular embryo and then into a fetus.