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Virtual Karyotype
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. Background A karyotype (Fig 1) is the characteristic chromosome complement of a eukaryote species.White M.J.D. 1973. ''The chromosomes''. 6th ed, Chapman & Hall, London. p28 A karyotype is typically presented as an image of the chromosomes from a single cell arranged from largest (chromosome 1) to smallest (chromosome 22), with the sex chromosomes (X and Y) shown last. Historically, karyotypes have been obtained by staining cells after they have been chemically arrested during cell division. Karyotypes have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karyotype
A karyotype is the general appearance of the complete set of metaphase 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. A karyogram or idiogram is a graphical depiction of a karyotype, wherein chromosomes are organized in pairs, ordered by size and position of centromere for chromosomes of the same size. Karyotyping generally combines light microscopy and photography, and results in a photomicrographic (or simply micrographic) karyogram. In contrast, a schematic karyogram is a designed graphic representation of a karyotype. In schematic karyograms, just one of the sister chromatids of each chromosome is generally shown for brevity, and in reality they are generally so close together that they look as one on photomicrographs as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Duplication
Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene. Gene duplications can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements. Common sources of gene duplications include ectopic recombination, retrotransposition event, aneuploidy, polyploidy, and replication slippage. Mechanisms of duplication Ectopic recombination Duplications arise from an event termed unequal crossing-over that occurs during meiosis between misaligned homologous chromosomes. The chance of it happening is a function of the degree of sharing of repetitive elements between two chromosomes. The products of this recombination are a duplication at the site of the exchange and a reciprocal deletion. Ectopic recombination ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Identical By Descent
A DNA segment is identical by state (IBS) in two or more individuals if they have identical nucleotide sequences in this segment. An IBS segment is identical by descent (IBD) in two or more individuals if they have inherited it from a common ancestor without recombination, that is, the segment has the same ancestral origin in these individuals. DNA segments that are IBD are IBS per definition, but segments that are not IBD can still be IBS due to the same mutations in different individuals or recombinations that do not alter the segment. Theory All individuals in a finite population are related if traced back long enough and will, therefore, share segments of their genomes IBD. During meiosis segments of IBD are broken up by recombination. Therefore, the expected length of an IBD segment depends on the number of generations since the most recent common ancestor at the locus of the segment. The length of IBD segments that result from a common ancestor ''n'' generations in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplotype
A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA organized in two sets of pairwise similar chromosomes. The offspring gets one chromosome in each pair from each parent. A set of pairs of chromosomes is called diploid and a set of only one half of each pair is called haploid. The haploid genotype (haplotype) is a genotype that considers the singular chromosomes rather than the pairs of chromosomes. It can be all the chromosomes from one of the parents or a minor part of a chromosome, for example a sequence of 9000 base pairs. However, there are other uses of this term. First, it is used to mean a collection of specific alleles (that is, specific DNA sequences) in a cluster of tightly linked genes on a chromosome that are likely to be inherited together—that is, they are likely to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loss Of Heterozygosity
Loss of heterozygosity (LOH) is a type of genetic abnormality in diploid organisms in which one copy of an entire gene and its surrounding chromosomal region are lost. Since diploid cells have two copies of their genes, one from each parent, a single copy of the lost gene still remains. But any heterozygosity, slight differences between the versions of the gene inherited from each parent, is no longer present. In cancer The loss of heterozygosity is a common occurrence in cancer development. Originally, a heterozygous state is required and indicates the absence of a functional tumor suppressor gene copy in the region of interest. However, many people remain healthy with such a loss, because there still is one functional gene left on the other chromosome of the chromosome pair. The remaining copy of the tumor suppressor gene can be inactivated by a point mutation or via other mechanisms, resulting in a loss of heterozygosity event, and leaving no tumor suppressor gene to protect th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uniparental Disomy
Uniparental disomy (UPD) occurs when a person receives two copies of a chromosome, or of part of a chromosome, from one parent and no copy from the other parent. UPD can be the result of heterodisomy, in which a pair of non-identical chromosomes are inherited from one parent (an earlier stage meiosis I error) or isodisomy, in which a single chromosome from one parent is duplicated (a later stage meiosis II error). Uniparental disomy may have clinical relevance for several reasons. For example, either isodisomy or heterodisomy can disrupt parent-specific genomic imprinting, resulting in imprinting disorders. Additionally, isodisomy leads to large blocks of homozygosity, which may lead to the uncovering of recessive genes, a similar phenomenon seen in inbreeding, inbred children of consanguinity, consanguineous partners. UPD has been found to occur in about 1 in 2,000 births. Pathophysiology UPD can occur as a random event during the formation of egg cells or spermatozoon, sperm cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Her2Neu
Her is the objective and possessive form of the English-language feminine pronoun she. Her, HER or H.E.R. may also refer to: Arts, entertainment and media Music * H.E.R. (born 1997), American singer ** ''H.E.R.'' (album), 2017 * HIM (Finnish band), once known as HER in the United States Songs * "Her" (Megan Thee Stallion song) * "Her", a song by Stan Getz from the album ''Focus'', 1961 * "Her", a song by Guy from the album '' The Future'', 1990 * "Her", a song by Swans from the album ''Omniscience'', 1992 * "Her", a song by Pigeonhed from the album ''Pigeonhed'', 1993 * "Her", a song by Tindersticks from the album ''Tindersticks'', 1993 * "Her", a song by Aaron Tippin from the album '' What This Country Needs'', 1999 * "Her", a song by Musiq from the album '' Soulstar'', 2003 * "Her", a song by Eels from the album '' B-Sides & Rarities 1996–2003'', 2005 * "Her", a song by Tyler, the Creator from the album ''Goblin'', 2011 * "Her", a song by Poppy from the album '' Flux'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herceptin
Trastuzumab, sold under the brand name Herceptin among others, is a monoclonal antibody used to treat breast cancer and stomach cancer. It is specifically used for cancer that is HER2 receptor positive. It may be used by itself or together with other chemotherapy medication. Trastuzumab is given by slow injection into a vein and injection just under the skin. Common side effects include fever, infection, cough, headache, trouble sleeping, and rash. Other severe side effects include heart failure, allergic reactions, and lung disease. Use during pregnancy may harm the baby. Trastuzumab works by binding to the HER2 receptor and slowing down cell replication. Trastuzumab was approved for medical use in the United States in September 1998, and in the European Union in August 2000. It is on the World Health Organization's List of Essential Medicines. A biosimilar was approved in the European Union in November 2017, and in the United States in December 2018. Medical uses The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oncogenes
An oncogene is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels.Kimball's Biology Pages. "Oncogenes" Free full text Most normal cells will undergo a programmed form of rapid cell death () when critical functions are altered and malfunctioning. Activated oncogenes can cause those cells designated for apoptosis to survive and proliferate instead. Most oncogenes began as proto-oncogenes: normal genes involved in cell growth and proliferation or inhibition of apoptosis. If, through mutation, normal genes promoting cellular growth are up-regulated (gain-of-function mutation), they will predis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplification (molecular Biology)
Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene. Gene duplications can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements. Common sources of gene duplications include ectopic recombination, retrotransposition event, aneuploidy, polyploidy, and replication slippage. Mechanisms of duplication Ectopic recombination Duplications arise from an event termed unequal crossing-over that occurs during meiosis between misaligned homologous chromosomes. The chance of it happening is a function of the degree of sharing of repetitive elements between two chromosomes. The products of this recombination are a duplication at the site of the exchange and a reciprocal deletion. Ectopic recombination i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
