Deletion (genetics)
In
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.[3][4][5]
Deletions can be caused by errors in
Causes
Causes include the following:
- Losses from translocation
- Chromosomal crossovers within a chromosomal inversion
- Unequal crossing over
- Breaking without rejoining
Types
Types of deletion include the following:
- Terminal deletion – a deletion that occurs towards the end of a chromosome.
- Intercalary/interstitial deletion – a deletion that occurs from the interior of a chromosome.
- Microdeletion – a relatively small amount of deletion (up to 5Mb that could include a dozen genes).
Micro-deletion is usually found in children with physical abnormalities. A large amount of deletion would result in immediate abortion (miscarriage).
Nomenclature
The
Effects
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, e.g. Williams syndrome.
Deletion of a number of pairs that is not evenly divisible by three will lead to a
Deletions are responsible for an array of genetic disorders, including some cases of male
Microdeletions are associated with many different conditions, including Angelman Syndrome, Prader-Willi Syndrome, and DiGeorge Syndrome.[10] 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.[11]
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
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.[13]
Detection
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 be as high as >30,000 "bands" and the size of chromosomal deletion detected could as small as 5–20 kb in length.[14] Other computation methods were selected to discover DNA sequencing deletion errors such as end-sequence profiling.[15][16]
Mitochondrial DNA deletions
In the yeast
See also
- Indel
- Chromosome abnormalities
- Null allele
- List of genetic disorders
- Medical genetics
- Microdeletion syndrome
- Chromosomal deletion syndrome
- Insertion (genetics)
- 10q26 deletion
References
- ^ ISBN 978-0072951745.
- )
- PMID 23692220.
- PMID 24206351.
- PMID 24854722.
- PMID 31228194.)"
{{cite journal}}
: CS1 maint: multiple names: authors list (link)
- "This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/ - ^ "ISCN Symbols and Abbreviated Terms". Coriell Institute for Medical Research. Retrieved 2022-10-27.
- ^ LSDB — Controlled vocabulary terms Archived 2011-10-06 at the Wayback Machine at The GEN2PHEN Knowledge Centre. Posted Fri, 08/01/2010.
- ISBN 978-1-4160-2973-1.
- ISBN 978-0-12-410529-4, retrieved 2022-01-07
- PMID 26022164.
- PMID 21390129.
- PMID 35030162.
- S2CID 28030180.
- S2CID 2737235. Archived from the original(PDF) on 2020-05-31. Retrieved 2014-01-10.
- PMID 12788976.
- ^ PMID 26540.