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In genetics, a deletion (also called gene deletion, deficiency, or Deletion anomaly mutation) (sign: Δ) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is left out during DNA replication. Any number of nucleotides can be deleted, from a single Nucleobase to an entire piece of chromosome. Some have fragile spots where breaks occur, which result in the deletion of a part of the chromosome. The breaks can be induced by heat, viruses, radiation, or chemical reactions. When a chromosome breaks, if a part of it is deleted or lost, the missing piece of chromosome is referred to as a deletion or a deficiency.
For synapsis to occur between a chromosome with a large intercalary deficiency and a normal complete homolog, the unpaired region of the normal homolog must loop out of the linear structure into a deletion or compensation loop.
The smallest single base deletion mutations occur by a single base flipping in the template DNA, followed by template DNA strand slippage, within the DNA polymerase active site.
Deletions can be caused by errors in chromosomal crossover during meiosis, which causes several serious . Deletions that do not occur in multiples of three bases can cause a frameshift by changing the 3-nucleotide protein reading frame of the genetic sequence. Deletions are representative of eukaryotic organisms, including humans and not in prokaryotic organisms, such as bacteria.
Micro-deletion is usually found in children with physical abnormalities. A large amount of deletion would result in immediate abortion (miscarriage).
Deletion of a number of pairs that is not evenly divisible by three will lead to a frameshift mutation, causing all of the occurring after the deletion to be read incorrectly during translation, producing a severely altered and potentially nonfunctional protein. In contrast, a deletion that is evenly divisible by three is called an in-frame deletion. LSDB — Controlled vocabulary terms at The GEN2PHEN Knowledge Centre. Posted Fri, 08/01/2010.
Deletions are responsible for an array of genetic disorders, including some cases of male infertility, two thirds of cases of Duchenne muscular dystrophy, and two thirds of cases of cystic fibrosis (those caused by ΔF508). (2025). 9781416029731, Saunders/Elsevier. ISBN 9781416029731 Deletion of part of the short arm of chromosome 5 results in Cri du chat syndrome. Deletions in the SMN-encoding gene cause spinal muscular atrophy, the most common genetic cause of infant death.
Microdeletions are associated with many different conditions, including Angelman Syndrome, Prader-Willi Syndrome, and DiGeorge Syndrome. Some syndromes, including Angelman syndrome and Prader-Willi syndrome, are associated with both microdeletions and genomic imprinting, meaning that same microdeletion can cause two different syndromes depending on which parent the deletion came from.
Recent work suggests that some deletions of highly conserved sequences (CONDELs) may be responsible for the evolutionary differences present among closely related species. Such deletions in humans, referred to as hCONDELs, may be responsible for the anatomical and behavioral differences between humans, chimpanzees and other varieties of mammals like ape or Monkey
Recent comprehensive patient-level classification and quantification of driver events in TCGA cohorts revealed that there are on average 12 driver events per tumor, of which 2.1 are deletions of tumor suppressors.
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