- Deletion (genetics)
In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) (sign: Δ) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is missing. Deletion is the loss of genetic material. Any number of nucleotides can be deleted, from a single base to an entire piece of chromosome. Deletions can be caused by errors in chromosomal crossover during meiosis. This causes several serious genetic diseases. Deletion is also causing frameshift.
Causes include the following:
- Losses from translocation
- Chromosomal crossovers within a chromosomal inversion
- Unequal crossing over
- Breaking without rejoining
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.
Types of deletion include the following:
- Terminal Deletion - a deletion that occurs towards the end of a chromosome.
- Intercalary Deletion / Interstitial Deletion - a deletion that occurs from the interior of a chromosome.
Small deletions are less likely to be fatal; large deletions are usually fatal - there are always variations based on which genes are lost. Some medium-sized deletions lead to recognizable human disorders.
Deletion of a number of base pairs that is not evenly divisible by three will lead to a frameshift mutation, causing all of the codons 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.
Deletions are responsible for an array of genetic disorders, including some cases of male infertility and two thirds of cases of Duchenne muscular dystrophy. Deletion of part of the short arm of chromosome 5 results in a syndrome called Cri du chat, French for "cry of the cat" syndrome. It is found in approximately 1 in 50,000 live births. The surviving infants have a distinctive cry, severe mental retardation, and shortened life span.
The introduction of molecular techniques in conjunction with classical cytogenetic methods has in recent years greatly improved the diagnostic potential for chromosomal abnormalities. In particular, microarray-comparative genomic hybridization (CGH) based on the use of BAC clones promises a sensitive strategy for the detection of DNA copy-number changes on a genome-wide scale. The resolution of detection could as high as >30,000 "bands" and the size of chromosomal deletion detected could as small as 5–20 kb in length.
- ^ a b c Lewis R. 2005. Human Genetics: Concepts and Applications, 6th Ed. McGraw Hill, New York.
- ^ LSDB - Controlled vocabulary terms at The GEN2PHEN Knowledge Centre. Posted Fri, 08/01/2010.
- ^ Ren, H (May 2005). "BAC-based PCR fragment microarray: high-resolution detection of chromosomal deletion and duplication breakpoints". Human Mutations 25 (5): 476–482. PMID 15832308.
Mutation Mechanisms of mutation. Mutation with respect to structure.Large scale mutationChromosomal translocations · Chromosomal inversions Mutation with respect to overall fitness.Deleterious mutation · Advantageous mutation · Neutral mutation · Nearly neutral mutation Pathology: chromosome abnormalities (Q90–Q99 · 758) AutosomalMonosomies/deletions1q21.1 deletion syndrome/1q21.1 duplication syndrome/TAR syndrome (1) · Wolf-Hirschhorn syndrome (4) · Cri du chat/Chromosome 5q deletion syndrome (5) · Williams syndrome (7) · Jacobsen syndrome (11) · Miller–Dieker syndrome/Smith–Magenis syndrome (17) · DiGeorge syndrome (22) · 22q13 deletion syndrome (22)
genomic imprinting (Angelman syndrome/Prader–Willi syndrome (15))Distal 18q-/Proximal 18q-
X/Y linked TranslocationsLymphoidMyeloidOther Other
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deletion — deletion. См. делеция. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
deletion mapping — deletion mapping. См. делеционное картирование. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
deletion method — deletion method. См. метод делеций. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
Deletion — For the deletion policy in Wikipedia, see Wikipedia:Deletion policy Deletion is the act of deleting or removal by striking out material, such as a word or passage, that has been removed from a body of written or printed matter. Deletion may refer … Wikipedia
deletion — [dē lē′shən, dilē′shən] n. [L deletio] 1. a deleting or being deleted 2. a deleted word, passage, etc. 3. Genetics the absence of some normal portion of a chromosome … English World dictionary
Deletion — Loss of a segment of DNA from a chromosome (and hence from the genome). The first human chromosome deletion was detected in 1963 by Jerome Lejeune and his colleagues in Paris. They discovered loss of part of 5p, the short (p) arm of chromosome 5 … Medical dictionary
Deletion mapping — In genetics and especially genetic engineering, deletion mapping is a technique used to ascertain the location of mutation sites within a gene. The principle of deletion mapping involves crossing a strain who has a point mutation in a gene, with… … Wikipedia
deletion — /di lee sheuhn/, n. 1. an act or instance of deleting. 2. the state of being deleted. 3. a deleted word, passage, etc. 4. Genetics. a type of chromosomal aberration in which a segment of the chromosome is removed or lost. [1580 90; < L deletion… … Universalium
deletion — deficiency; n. (in genetics) a type of mutation involving the loss of DNA. The deletion may be small, affecting only a portion of a single gene, or large, resulting in loss of a part of a chromosome and affecting many genes … The new mediacal dictionary
deletion — noun 1. any process whereby sounds or words are left out of spoken words or phrases • Syn: ↑omission • Hypernyms: ↑linguistic process • Hyponyms: ↑aphaeresis, ↑apheresis, ↑aphesis, ↑ … Useful english dictionary