Talk:Copy number variation

An example out of place?
I cite: "Like other types of genetic variation, some CNVs have been associated with susceptibility or resistance to disease. Gene copy number can be elevated in cancer cells. For instance, the EGFR copy number can be higher than normal in non-small cell lung cancer. [7" - Why the clause about cancer comes after the phrase about susceptibility? As I understand, the tumour is usually the place where mutations are rife, so CNVs in the tumour cells are likely not the CNVs that the organism inherited or has been having since conception. If I'm right, the two sentences about cancer should be separated into another paragraph. --CopperKettle (talk) 20:42, 19 November 2008 (UTC)

Introductory paragraph
I think the intro paragraph could be more helpful. It currently defines "copy-number variation" in terms of "copy-number differences", which is essentially the same thing. I would also question whether it's correct to say CNVs are "segments of DNA." It seems to me that CNVs affect segments of DNA. --Krokicki (talk) 21:34, 17 December 2008 (UTC)

The introduction paragraph does not seem to have much to do with how the concept of CNV is used in the field of human genetics. In human genetics, and more specifically, in the diagnosis and research of disease, CNV's are generally considered (pathogenic) changes in copy number compared to a "standard" genome. As most human genes are diploid (meaning one copy of each parent is inherited), for most genes, this means the standard copy number for a gene (or part of a gene) is TWO. Copy number variation then, is if a person has a deletion (only 1, or even 0 copies present) or a duplication (3 or more copies present) in their genome. These CNV changes may give rise to genetic disorders. CNVS, in this way, are often presented as one causal way of genetic disease, with SNVs (single nucleotide variations, in other words: changes of only a single basepair) as the main other. Besides these two types of genetic mutations, there are some smaller genetic causes of disease, such as balanced translocations, or changes in the number of repeat elements (such as is the case in Huntington's disease). The first sentence of this article, seems to have the latter category in mind:

"Copy number variation (CNV) is a phenomenon in which sections of the genome are repeated and the number of repeats in the genome varies between individuals"

However, CNV has to do with the differences in genetic copy number of an individual compared to the "standard", which again, is usually two. These two copies, are NOT repeats: they are two of the same genes sitting on the same chromosmal location on DIFFERENT CHROMOSOMAL ALLELES: one inherited from the mother, one from the father. The sentence above makes on think of repeat elements, such as IS the case in Huntington disease, but again, this is NOT what is meant with CNV, or CNV analysis, in Human Genetics.

In my eyes, the article needs a complete overhaul written from a different starting point about what CNV stands for. — Preceding unsigned comment added by 213.127.202.242 (talk) 15:33, 29 March 2022 (UTC)

A quote
Q: Just curiosity on my part, but you seem to use terminology other than CNV in the paper: things like unbalanced micro-rearrangements. Is that just a preference of nomenclature or is there some theoretical thing embedded in that? EE: Actually, that stems from complaints from the cytogenetics community. There are well-established professors in cytogenetics that have criticized the use of CNV to refer to something that is pathogenic. And that’s because implied in copy number variant, at least until probably last year, was the idea that variant equals benign. Microdeletion and microduplication to cytogeneticists typically means that you have something pathogenic, but there was actually a move among a few cytogeneticists to write a white paper or a piece that would help clarify this. But I would have to say that in the last year there’s been so much interchange between the use of CNV and microdeletion and microduplication, I think it’s a foregone conclusion now that it's almost impossible to stem that tide and change the usage back to the way that cytogeneticists viewed it originally. --CopperKettle (talk) 00:30, 24 December 2008 (UTC)

What is a Copy Number?
This article talks about "copy number" as if it were a specifically genetic phenomenon, which leads me to believe that it isn't simply the "number of copies" of a gene, but is rather some other thing -- an internal count of the number of times a gene has been copied, perhaps? That seems strange to me, but it's the only obvious way to make sense of this article. I think there needs to be a definition of "copy number" before it's clear what a "copy number variation" is. 24.238.113.249 (talk) 15:34, 15 October 2009 (UTC)

You don't really explain why that's the only obvious way to make sense of the article. Your first belief is correct, simply the number of copies of a genetic region (not gene per say). —Preceding unsigned comment added by 130.91.11.246 (talk) 16:58, 9 March 2010 (UTC)

Requested move
✅. Reliable sources vary in their use, but the hypenated version seems to be strictly correct. Fences &amp;  Windows  22:21, 1 July 2010 (UTC)

Copy number variation → — Copy-number is a compound modifier of variation and therefore should be hyphenated. -Cwenger (talk) 15:27, 17 June 2010 (UTC)

Proposal to change the name of this article
I propose changing the name of this article from "Gene copy number" to "Copy number variation". Comments? -- Fat Cigar 14:33, 16 August 2008 (UTC)


 * I'm in favour. There is already a redirect from 'Copy number variant' to 'Gene copy number'. T0mpr1c3 (talk) 15:08, 27 August 2008 (UTC)

I'd like to change the title to Copy Number Variant —Preceding unsigned comment added by 130.91.11.246 (talk) 16:55, 9 March 2010 (UTC)

Ambiguous sentence
Currently the second sentence of the article says

CNVs correspond to relatively large regions of the genome that have been deleted (fewer than the normal number) or duplicated (more than the normal number) on certain chromosomes

The sentence doesn't make clear what is being deleted or duplicated. Is it the nucleotide sequence itself, including enhancers and other factors? Also is this on an population level or organism level? I don't know anything about CNVs so I cannot disambiguate, but I hope someone with expertise can. Paulish (talk) 19:43, 10 September 2012 (UTC)

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