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Chromosome Aberrations definition: Abnormal number or structure of chromosomes. Many chromosome aberrations, but not all, are the cause of CHROMOSOME DISORDERS.
chromosome aberration definition: irregularity in the number or structure of chromosomes that may alter the course of development.
Cytogenetic Abnormality definition: An irregularity in the number or structure of chromosomes, usually in the form of a gain (duplication), loss (deletion), exchange (translocation), or alteration in sequence (inversion) of genetic material.
chromosome disorder definition: clinical conditions caused by an abnormal chromosome constitution in which there is extra or missing chromosome material, either a whole chromosome or a chromosome segment.
Chromosome Disorders definition: Clinical conditions caused by an abnormal chromosome constitution in which there is extra or missing chromosome material (either a whole chromosome or a chromosome segment). (from Thompson et al., Genetics in Medicine, 5th ed, p429)
Chromosome Deletion definition: Actual loss of a portion of the chromosome.
chromosome deletion definition: actual loss of a portion of or the entire chromosome.
Chromosomal Deletion definition: Loss of a portion of a chromosome arm.
Chromosome Fragility definition: Susceptibility of chromosomes to breakage leading to translocation; CHROMOSOME INVERSION; SEQUENCE DELETION; or other CHROMOSOME BREAKAGE related aberrations.
Chromosomes definition: In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
chromosome definition: in a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure containing DNA which carries the genetic information essential to the cell; the bacterial chromosome is a closed circle of double stranded DNA associated with the cell membrane; nuclear chromosomes are associated with RNA, histones and non histone proteins; the normal number of chromosomes in human somatic cells is 46.
chromosome definition: (KRO-mo-some) Part of a cell that contains genetic information. Except for sperm and eggs, all human cells contain 46 chromosomes.
chromosome definition: A structure composed of a very long molecule of DNA and associated proteins (e.g. histones) that carries hereditary information. [ISBN:0198547684]
Chromosome definition: Organelle part which consists of nucleotides arranged linearly into three regions, DNA replication origin, centromere and telomere. Examples: nuclear chromosome, sex chromosome.
Chromosome definition: One of the bodies in the cell nucleus that is the bearer of genes, has the form of a delicate chromatin filament during interphase, contracts to form a compact cylinder segmented into two arms by the centromere during metaphase and anaphase stages of cell division, and is capable of reproducing its physical and chemical structure through successive cell divisions.
chromosome inversion definition: chromosomal change in which a segment has been rotated by 180 degrees relative to the regions on either side and reinserted.
Chromosome Inversion definition: An aberration in which a chromosomal segment is deleted and reinserted in the same place but turned 180 degrees from its original orientation, so that the gene sequence for the segment is reversed with respect to that of the rest of the chromosome.
Chromosomal Inversion definition: A type of chromosome rearrangement in which a segment has been turned through 180 degrees (inverted), and inserted back into its original location on the chromosome.
chromosome translocation definition: rearrangement in which part of a chromosome is detached by breakage and becomes attached to another chromosome.
Translocation, Genetic definition: A type of chromosome aberration characterized by CHROMOSOME BREAKAGE and transfer of the broken-off portion to another location, often to a different chromosome.
Chromosomal Translocation definition: A genetic exchange where a piece of one chromosome is transfered to another chromosome.
chromosome XXXXY syndrome definition: A sex chromosome aneuploidy with an incidence of 1 in 85,000 male births. Principal findings include radioulnar synostosis, hypogonadism, mental retardation, and speech disorders. Associated disorders ara variable and may include characteristic facies, multiple skeletal abnormalities, and cardiac and genital malformations. Many features are similar to those seen in the Klinefelter syndrome (chromosome XXY syndrome), hence the synonym Klinefelter variant.
Chromosome Breakage definition: A type of chromosomal aberration involving DNA BREAKS. Chromosome breakage can result in CHROMOSOMAL TRANSLOCATION; CHROMOSOME INVERSION; or SEQUENCE DELETION.
chromosome breakage definition: Regulated cleavage of the developing macronuclear genome at a limited number of chromosome breakage sites (CBS). The macronuclear destined segment (MDS) sequence adjacent to the CBS (or separated from it by a BES) receives a macronuclear telomere following chromosome breakage. [GOC:ns]
Nijmegen breakage syndrome (NBS) definition: A disorder, wherein unstable chromosomes have a tendency to break and become rearranged, characterized by microcephaly, stunted growth, subnormal mental development, cafe-au-lait spots, and immunodeficiency. The syndrome is named after the University of Nijmegen in the Netherlands.
Nijmegen Breakage Syndrome definition: A disorder, wherein unstable chromosomes have a tendency to break and become rearranged, characterized by microcephaly, stunted growth, subnormal mental development, cafe-au-lait spots, and immunodeficiency. The syndrome is named after the University of Nijmegen in the Netherlands. (JABL99)
Nijmegen breakage syndrome definition: characterized by short stature, progressive microcephaly with loss of cognitive skills, premature ovarian failure in females, recurrent sinopulmonary infections, and an increased risk for cancer, particularly lymphoma.
Nijmegen Breakage Syndrome definition: A chromosome instability syndrome resulting from a defective response to DNA double-strand breaks. In addition to characteristic FACIES and MICROCEPHALY, patients have a range of findings including RADIOSENSITIVITY, immunodeficiency, increased cancer risk, and growth retardation. Causative mutations occur in the NBS1 gene, located on human chromosome 8q21. NBS1 codes for nibrin, the key regulator protein of the R/M/N (RAD50/MRE11/NBS1) protein complex which senses and mediates cellular response to DNA DAMAGE caused by IONIZING RADIATION.
synapsis definition: The cell cycle process whereby the side by side pairing and physical juxtaposition of homologous chromosomes is created at the metaphase plate. [GOC:elh]
Chromosome Pairing definition: The alignment of CHROMOSOMES at homologous sequences.
Chromosome Structures definition: Structures which are contained in or part of CHROMOSOMES.
Chromosome Structure definition: The 3-D organization of histones and other proteins on chromosomal DNA in the nucleus and allow for its form and function during cellular growth and division.
Colinearity, Chromosomal definition: The similarity between chromosome segments or chromosomes in the linear arrangement of genes (GENE ORDER) or genetic markers.
Chromosomal Instability definition: The instability of chromosomes is attributed to the continuous formation of novel chromosome mutations. These mutations form at an elevated rate in comparison to the normal cell population. The increased frequency of structural chromosome aberrations can be caused by an abnormally high incidence of DNA double-strand breaks and translocations. Screening for chromosomal breakage and rearrangement is used as a diagnostic tool in Fanconi anemia.
Chromosomal Instability definition: An increased tendency to acquire CHROMOSOME ABERRATIONS when various processes involved in chromosome replication, repair, or segregation are dysfunctional.
Balanced Chromosomal Translocation definition: Interchanges of genetic material among different chromosomes following the breaking off of pieces of chromosomes such that the total chromosome composition may still contain all of the genetic material.Balanced Chromosomal Rearrangement.
Chromosomal Duplication definition: An irregularity in the number of chromosomes, usually in the form of a gain of genetic material. (NCI)
Chromosomal Loss definition: Loss of an entire chromosome or chromosome arm.
Chromosome Territory definition: The physical volume occupied by a specific chromosome in the interphase nucleus. The territories from distinct chromosomes do not appear to overlap, preventing an intermingling of the decondensed chromatin. Relative to a nuclear landmark (e.g. nucleolus), chromosome territories appear to differ from cell to cell.
Allele_In_Chromosomal_Location definition: This role is used for alleles whose location has changed from the wild-type gene chromosomal location. This role is used to assert a new location that differs from the wild-type gene chromosomal location. Chromosome number or chromosome arm specifies the location of allele and in such cases chromosome band becomes essentially meaningless. The domain and range kind for this role are Gene_Kind and Anatomy_Kind, respectively.
chromosome passenger complex definition: A eukaryotically conserved protein complex that localizes to kinetochores in early mitosis, the spindle mid-zone in anaphase B and to the telophase midbody. It has been proposed that the passenger complex coordinates various events based on its location to different structures during the course of mitosis. Complex members include the BIR-domain containing protein survivin, aurora kinase and INCENP. [GOC:vw, PMID:16824200]
chromosomal part definition: Any constituent part of a chromosome, a structure composed of a very long molecule of DNA and associated proteins (e.g. histones) that carries hereditary information. [GOC:jl]
Chromosomal Position Effects definition: The effects on gene expression that depend on the location of a gene with respect to its neighboring genes and region of chromosome. Stable position effects are sequence dependent. Variegated position effects depend on whether the gene is located in or adjacent to HETEROCHROMATIN or EUCHROMATIN.