Talk:Genetic linkage

Moved from article
Editor's note: There has also been many diseases and conditions that have been treated or discovered using genetic linkage. &mdash;The preceding unsigned comment was added by 68.197.225.54 (talk • contribs).

Why is this phenomenon not mentioned more in non-scientific media?
I find it fascinating that geneticists know which human traits are inherited together. I imagine they can predict, for example, the chances that a child who gets his father's hair color will also get some other particular trait from him as well ... and which ones the child will almost certainly get. I sometimes note a physical similarity between a child and one of the parents, and try to see what temperamental or intellectual characteristic they also did or did not get. In so speculating, I'm sort of imagining the kind of genetic map that the experts must have down pat.

I would think these associations would be all over popular magazines and gossip columns. Why not? Do most people not care? Or aren't they able to grasp what's going on? Anyone care to weigh in on this? Sfahey 02:49, 6 March 2006 (UTC)

-- I feel that's a gross overstatement of geneticists' current capabilities. They may have some traits linked together, but they don't know whether or not your father's hair color comes along with his alcoholism and good work ethic.

--

...although you are thinking along the right lines, Sfahey. The trouble is so many of the traits you might be interested in (like alcoholism) are complex, meaning that they have many genetic components in addition to sensitivity to many environmental exposures. So if, say, one gene contributes 1% of the genetic heritability of alcoholism and is closely linked to a visible trait (such as hair color), we may never notice it because without a huge population to study we would have a lot of trouble detecting it. However, some really cool genes are linked because of their close proximity to each other. For example, some olfactory/scent genes are located right next to the HLA genes (which encode a major component of your immune system). Some studies have shown that people preferentially mate with individuals of different HLA type- and we may use smell to do that! I find it fascinating, too. If more people like you were interested, popular magazines and gossip columns might give the topic some press. Though I'm not sure that's always a good thing :)

Nat Genet. 2002 Feb;30(2):175-9. Epub 2002 Jan 22. Paternally inherited HLA alleles are associated with women's choice of male odor.
 * Thanks for response.Sfahey 23:27, 6 February 2007 (UTC)

--

Just to add another point to Sfahey's comment - the distance along a chromosome one can predict genotypes is perhaps shorter than you might think. The HapMap project only lists [SNP]-SNP correlations up to a maximum distance of 2 million base pairs (2Mb), of which you might expect about 700-1000 SNPs (depending on which part of which chromosome you are examining). Buzwad 12:57, 31 July 2007 (UTC)

Image
This image looks like it could be used in this article: Image:Linkage.png --apers0n 07:49, 24 July 2006 (UTC)

Added a section of Genetic Map/linkage map
Genetic map and linkage map (or Genetic linkage map) is essentially the same and relies on the principle of genetic linkage. There was a genetic map article but it was a stub anyway so I moved it here.

Merge from "recombination frequency"
Oppose merge Unless this article is preserved as the primary title. "Linkage" is a much more familiar term. It shouldn't be stuck inside an article on Recombination frequency, which fewer people would go to look up. Sfahey 02:58, 9 December 2006 (UTC)


 * I agree and have reversed the direction of the proposed merge to reflect this comment.Dr d12 20:49, 9 December 2006 (UTC)

Support per above Sfahey 04:23, 12 December 2006 (UTC)

As a college student taking an upper level Genetics course, I support merging recombination frequency into gene linkage, as it is a part of undertanding the whole picture. Recombination frequency is a section in the chapter on gene linkage in our book, and is discussed heavily in our lectures. -ZRiley

Merge from "Linked genes"
Support. I agree, these are duplicate articles. The problem is this: can we use anything from the "linked genes" article here, or should it just be deleted? Dr d12 03:28, 23 January 2007 (UTC)

Suggested edit to page
The opening paragraph begins: "Genetic linkage occurs when particular alleles are inherited jointly. Typically, an organism can pass on an allele without regard to which allele was passed on for a different gene."

I would suggest it reads like this: "Genetic linkage occurs when particular alleles are inherited jointly. Typically, an organism can pass on an allele without regard to which allele was passed on for a different chromosome."

Any comments?

Buzwad 13:04, 31 July 2007 (UTC)

The last paragraph under Linkage Mapping, especially this sentence: However, if a mutation in gene B that causes some disease happened recently in a particular subpopulation, it almost always occurs with a particular allele of gene A if the individual in which the mutation occurred had that variant of gene A and there have not been sufficient generations for recombination to happen between them (presumably due to tight linkage on the genetic map) seems linguistically unclear to me. Could it be changed to something like this: If a disease-causing mutation happened recently in history, individuals with this disease very often have the same alleles of other genes as the individual in which the mutation originally occured (presumably due to tight linkage on the genetic map)

? --Akita86 (talk) 15:06, 19 May 2008 (UTC)

The article says that "independent assortment occurs when the genes affecting the phenotypes are found on different chromosomes or separated by a great enough distance on the same chromosome that recombination occurs at least half of the time.". This is not quite accurate. The correlation between two loci decreases with distance and with the number of generations that have passed since the deviating alleles at the two loci were established. It may go too far to give the mathematical formulars in this article but I think it would be prudent to make clear that there is nothing special about the distance that corresponds to 50% recombination. Depending on the study's sensitivity to linkage, one might as well say 40% or 70% or whatever. Helenuh (talk) 15:03, 3 June 2008 (UTC)

Why Does Physical Map Redirect to Genetic Linkage?
Seriously Why? I want to look up the kind of information Physical maps convey and I get Genetics. Arkkeeper (talk) 17:56, 29 May 2008 (UTC)

Tooo much redundant information here...
I guess its up to me to fix it though right... --Dan|(talk) 14:13, 22 July 2008 (UTC)

lead section too long
The lead section (paragraphs before table of contents) is too long for this article. It should give a much more concise summary than currently the case (as of 2008-12-16).

Keep up the good work.

Best, j

frequency of crossover
The frequency of recombination should not be confused with the frequency of crossover, since each crossover event produces two recombinant gametes. Also, in the case of double-crossover, two crossover events could produce no recombinant gametes. Therefore, the frequency of crossover is greater than or equal to the frequency of recombination / (over) 2 —Preceding unsigned comment added by 208.81.93.216 (talk) 10:27, 8 October 2009 (UTC)

Re-working the article
This article has a really good foundation, but (as mentioned above) there's a lot of redundancy and a lot of extraneous information, as well as too few references. I'm going to start overhauling/reworking the article in hopes to improve it a bit; make clear the history, clarify the definition of genetic linkage, and make some of the prose easier to read/understand. Any and all help would be appreciated! Jhfortier (talk) 00:01, 14 February 2010 (UTC)

I like this article and think it's just the right length; the topic is not easy, but I think it's handled quite well. The truth is that this technique may not be as useful as we are more readily able to sequence genes which is a more concrete (and easier to understand) technique.155.58.210.15 (talk) 20:05, 22 March 2010 (UTC)doctorwolfie (talk) 20:07, 22 March 2010 (UTC)

I think the main problem with this article is it tries to be both a serious encyclopedia article and a simple english article simultaneously. Someone should create a simple english verison and that will allow the main article to stand alone 137.187.44.106 (talk) 14:34, 15 April 2010 (UTC)

Potentially wrong statement
There is the following sentence in the background section: "For example, in fruit flies, the genes affecting eye color and wing length are inherited together because they appear on the same chromosome.". If I understand correctly, it is not enough to have the genes in the same chromosome but it is also needed that they are close enough to each other. Could someone explain whether the sentence is wrong or I miss something? Cheater no1 (talk) 00:58, 14 November 2011 (UTC)

Conceptually wrong statement
The following paragraph is highly problematic:

"However, it is important to note that recombination frequency tends to underestimate the distance between two linked genes. This is because as the two genes are located farther apart, the chance of double or even number of crossovers between them also increases. Double or even number of crossovers between the two genes results in them being cosegregated to the same gamete, yielding a parental progeny instead of the expected recombinant progeny."

The reason is that, if two loci are far away from each other, their recombinant frequency will DEFINITELY increase. The frequency is in terms of a large number of offspring, not in terms of a single individual child.

The problem with the quoted paragraph is it attempts to use an INDIVIDUAL child where two loci far apart link together as a result of even number of crossover among them. It is important to note that in a second, third ... child, you will never be able to guarantee that the number of crossover between the two loci is still EVEN! As a result, as the number of children increases, the two loci would appear uncorrelated, even though some children may exhibit traits of linkage in these two loci. — Preceding unsigned comment added by Puekai (talk • contribs) 05:59, 30 January 2013 (UTC)

Assessment comment
Substituted at 15:55, 29 April 2016 (UTC)

The Bateson and Punnett experiment data
is presented twice in this article. Is this really desirable or necessary? —suzukaze (t・c) 19:43, 23 February 2017 (UTC)