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| Untersuchte Arbeit: Seite: 14, Zeilen: 1-18, 23-26 |
Quelle: Canales Walz 2011 Seite(n): 1, 3, Zeilen: 1: 3rd col., 5 ff.; 3: 1st col: 8ff |
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| 1.5 Copy number variation and phenotypic variability.
Is now known that any individual carries ~1000 CNV ranging from 443 bp to 1.28 Mb (Conrad et al 2010). This can lead to either too many or too few dosage sensitive genes, which might result in phenotypic variability, complex behavioural traits and disease susceptibility. Interestingly, CNVs have not only been associated with disease, but also with genome evolution and adaptive traits. The AMY1 gene, which encodes a protein that catalyses the first step in digestion of dietary starch and glycogen, constitutes an interesting example. It has been found that the copy number of this gene is three times higher in humans compared to chimpanzees, suggesting that humans were favoured in the gene dosage due to a concomitant increase of starch consumption (Perry et al,2007). However, it still remains the problem to understand if CNV means disease and how these structural changes and gene dosage alterations contribute on phenotypic outcomes. Actually we know that CNVs affected specific genes or chromosomal region, can lead to susceptibility and predisposition to certain diseases such as HIV, lupus, nephritis, pancreatitis and psoriasis among many other phenotypes (Canales 2011). However, it has been shown that individuals carrying the same rearrangement, for instance within an affected family, show differences in the manifestation of the investigated phenotype. [...] Further studies demonstrated that the variability can be due to the presence of an additional large deletion or duplication in the proband that resulted in a sensitized genetic background and consequently a more pronounced phenotype (Girirajan 2010). 14. Canales CP & Walz K. Copy number variation and susceptibility to complex traits. EMBO Mol Med. 2011 Jan;3(1):1-4. 19. Conrad DF, et al. Origins and functional impact of copy number variation in the human genome. Nature. 2010 Apr 1;464(7289):704-12. 23. Girirajan S. & Eichler E.E., Phenotypic variability and genetic susceptibility to genomic disorders. Human Molecular Genetics, 2010, Vol. 19, Review. 59. Perry GH, et al. Diet and the evolution of human amylase gene copy number variation. Nat Genet. 2007 Oct;39(10):1256-60. |
This can lead to either too many or too few dosage sensitive genes, which might result in phenotypic variability, complex behavioural traits and disease susceptibility. Interestingly, CNVs have not only been associated with disease, but also with genome evolution and adaptive traits. The AMY1 gene, which encodes a protein that catalyzes the first step in digestion of dietary starch and glycogen, constitutes an interesting example. It has been found that the copy number of this gene is three times higher in humans compared to chimpanzees, suggesting that humans were favoured in the gene dosage due to a concomitant increase of starch consumption. [...] (Perry et al, 2007).
[page 3] Moreover, it was found that any individual in average carries ∼1000 CNV ranging from 443 bp to 1.28 Mb, with a median size of 2.9 kb (Conrad et al, 2010). [...] [...] Another important question is the relative contribution of structural changes and gene dosage alterations on phenotypic outcomes. [...] Importantly, today we can assert that many CNVs, which affect specific genes and chromosomal regions, can lead to susceptibility and predisposition to certain diseases such as HIV, lupus, nephritis, pancreatitis and psoriasis among many other phenotypes. However, often the simple gene dosage difference cannot explain a certain difference in phenotype. It has been shown, for example that individuals who carry the same dosage for a particular gene or region, for instance within an affected family, show differences in the manifestation of the investigated phenotype. [...] Further studies demonstrated that the differences in the phenotypic variability were due to the presence of an additional large deletion or duplication (second hit) in the probands that resulted in a sensitized genetic background and consequently a more pronounced phenotype. [...] (Girirajan et al, 2010a,b), [...] 1. Conrad D, et al. Nature. 2010;464:704–712. 3. Girirajan S, et al. Nat Genet. 2010a;42:203–209. 6. Perry GH, et al. Nat Genet. 2007;39:1256–1260. |
The source is given somewhere in the middle. Perry et al. (2007) does not contain the parallel text. |
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