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A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by determining the chromosome complement of an individual, including the number of chromosomes and any abnormalities.
Cytogenetics is essentially a branch of genetics, but is also a part of cell biology/cytology, that is concerned with how the chromosomes relate to cell behaviour, particularly to their behaviour during mitosis and meiosis. Techniques used include karyotyping, analysis of G-banded chromosomes, other cytogenetic banding techniques, as well as molecular cytogenetics such as fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH).
In genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes balanced and unbalanced translocation, with two main types: reciprocal, and Robertsonian translocation. Reciprocal translocation is a chromosome abnormality caused by exchange of parts between non-homologous chromosomes. Two detached fragments of two different chromosomes are switched. Robertsonian translocation occurs when two non-homologous chromosomes get attached, meaning that given two healthy pairs of chromosomes, one of each pair "sticks" and blends together homogeneously.
A fusion gene is a hybrid gene formed from two previously independent genes. It can occur as a result of translocation, interstitial deletion, or chromosomal inversion. Fusion genes have been found to be prevalent in all main types of human neoplasia. The identification of these fusion genes play a prominent role in being a diagnostic and prognostic marker.
An isochromosome is an unbalanced structural abnormality in which the arms of the chromosome are mirror images of each other. The chromosome consists of two copies of either the long (q) arm or the short (p) arm because isochromosome formation is equivalent to a simultaneous duplication and deletion of genetic material. Consequently, there is partial trisomy of the genes present in the isochromosome and partial monosomy of the genes in the lost arm.
In genetics, a locus is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of protein-coding genes in a complete haploid set of 23 chromosomes is estimated at 19,000–20,000.
Polysomy is a condition found in many species, including fungi, plants, insects, and mammals, in which an organism has at least one more chromosome than normal, i.e., there may be three or more copies of the chromosome rather than the expected two copies. Most eukaryotic species are diploid, meaning they have two sets of chromosomes, whereas prokaryotes are haploid, containing a single chromosome in each cell. Aneuploids possess chromosome numbers that are not exact multiples of the haploid number and polysomy is a type of aneuploidy. A karyotype is the set of chromosomes in an organism and the suffix -somy is used to name aneuploid karyotypes. This is not to be confused with the suffix -ploidy, referring to the number of complete sets of chromosomes.
Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of the process. The base system of analysis revolves around general genetics. Basic studies include identification of genes and inherited disorders. This research has been conducted for centuries on both a large-scale physical observation basis and on a more microscopic scale. Genetic analysis can be used generally to describe methods both used in and resulting from the sciences of genetics and molecular biology, or to applications resulting from this research.
A chromosomal abnormality, chromosomal anomaly, chromosomal aberration, chromosomal mutation, or chromosomal disorder is a missing, extra, or irregular portion of chromosomal DNA. These can occur in the form of numerical abnormalities, where there is an atypical number of chromosomes, or as structural abnormalities, where one or more individual chromosomes are altered. Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. Chromosome anomalies usually occur when there is an error in cell division following meiosis or mitosis. Chromosome abnormalities may be detected or confirmed by comparing an individual's karyotype, or full set of chromosomes, to a typical karyotype for the species via genetic testing.
Ewing sarcoma is a type of pediatric cancer that forms in bone or soft tissue. Symptoms may include swelling and pain at the site of the tumor, fever, and a bone fracture. The most common areas where it begins are the legs, pelvis, and chest wall. In about 25% of cases, the cancer has already spread to other parts of the body at the time of diagnosis. Complications may include a pleural effusion or paraplegia.
Felix Mitelman is a Swedish geneticist and is professor of clinical genetics in Lund, Sweden. He is best known for his pioneering work on chromosome changes in cancer.
Virtual karyotype is the digital information reflecting a karyotype, resulting from the analysis of short sequences of DNA from specific loci all over the genome, which are isolated and enumerated. It detects genomic copy number variations at a higher resolution for level than conventional karyotyping or chromosome-based comparative genomic hybridization (CGH). The main methods used for creating virtual karyotypes are array-comparative genomic hybridization and SNP arrays.
The Atlas of Genetics and Cytogenetics in Oncology and Haematology, created in 1997 by Jean-Loup Huret is a collection of resources on genes, chromosomes anomalies, leukemias, solid tumours, and cancer-prone diseases. The project is accessible through Internet and is made of encyclopedic-style files, as well as traditional overviews, links towards websites and databases devoted to cancer and/or genetics, case reports in haematology. It also encompasses teaching items in various languages.
Breakage-fusion-bridge (BFB) cycle is a mechanism of chromosomal instability, discovered by Barbara McClintock in the late 1930s.
The Cancer Genome Anatomy Project (CGAP), created by the National Cancer Institute (NCI) in 1997 and introduced by Al Gore, is an online database on normal, pre-cancerous and cancerous genomes. It also provides tools for viewing and analysis of the data, allowing for identification of genes involved in various aspects of tumor progression. The goal of CGAP is to characterize cancer at a molecular level by providing a platform with readily accessible updated data and a set of tools such that researchers can easily relate their findings to existing knowledge. There is also a focus on development of software tools that improve the usage of large and complex datasets. The project is directed by Daniela S. Gerhard, and includes sub-projects or initiatives, with notable ones including the Cancer Chromosome Aberration Project (CCAP) and the Genetic Annotation Initiative (GAI). CGAP contributes to many databases and organisations such as the NCBI contribute to CGAP's databases.
Jean Loup Huret is a French scientist and medical practitioner specialist in genetics, honorary associate professor of medical genetics of the French Universities, working on chromosome abnormalities.
Jacqueline Jia-Kang Whang-Peng is a Taiwanese-American physician-scientist specialized in cytogenetics of cancer, as well as medical genetics, genetic oncology, and gene mapping. She was a researcher at the National Cancer Institute from 1960 to 1993.
XYYY syndrome, also known as 48,XYYY, is a chromosomal disorder in which a male has two extra copies of the Y chromosome. The syndrome is exceptionally rare, with only twelve recorded cases. The presentation of the syndrome is heterogeneous, but appears to be more severe than its counterpart XYY syndrome. Common traits include borderline to mild intellectual disability, infertility, radioulnar synostosis, and in some cases tall stature.
The chromosomal theory of cancer is a fundamental concept in cancer biology that suggests cancer is caused by genetic changes, particularly alterations in the structure or number of chromosomes in cells. These changes can lead to uncontrolled cell growth, a hallmark of cancer.
References
- ↑ Mitelman, Felix (1983). "Catalog of Chromosome Aberrations in Cancer". Cytogenetic and Genome Research. 36 (1–2): 1–3. doi: 10.1159/000131930 . PMID 6627995.
- ↑ Mitelman, Felix (1985). Catalog of chromosome aberrations in cancer (2nd ed.). New York: Liss. p. 707. ISBN 0-8451-2405-6.
- ↑ Mitelman, Felix (1988). Catalog of chromosome aberrations in cancer (3rd ed.). New York: Liss. p. 1146. ISBN 0-8451-4248-8.
- ↑ Mitelman, Felix (1991). Catalog of chromosome aberrations in cancer (4th ed.). New York: Wiley-Liss. p. 1986. ISBN 0-471-56087-1.
- ↑ Mitelman, Felix (1994). Catalog of chromosome aberrations in cancer (5th ed.). New York: Wiley-Liss. p. 4252. ISBN 0-471-11183-X.
- ↑ Mitelman, Felix (1998). Catalog of chromosome aberrations in cancer '98 (6th ed.). New York: Wiley-Liss. ISBN 0-471-17603-6.
- ↑ "Cancer Cytogenomics Resources".
- ↑ "Mitelman Database: About". Mitelman Database: Chromosome Aberrations and Gene Fusions in Cancer. Retrieved 27 April 2023.