Post by zephyrhillsusan on Oct 20, 2014 16:02:31 GMT -5
Several months ago I had a very informative discussion with someone at UCDavis VGL about the accuracy of parentage verification. This person gave me a very cogent explanation (which I am unable to replicate) and then referred me to a rather hidden article on the VGL website. I can figure out how to find a lot of things on the internet, but I would never have stumbled upon this!
I shared the link at the time, but it got rather lost at the end of a long discussion. I just shared it again, but in a thread about A&M, so anyone looking for it would never find it. With that in mind I thought I would share the link in its own thread so someone has a chance of finding it again.
Parentage Testing in Animal Pedigree Verification If you read far enough down in the article, it explains how the sire's and dam's genotypes are used to match with the calf's and gives some examples. I think the person I talked to on the phone explained "mating exclusion" MUCH better than the article does (part II). However, the final paragraph is very interesting:
(Emphasis added by me.)
I thought the final section on Accuracy was also very interesting, especially the final paragraph:
This was all very helpful to me, hope it will help someone else.
Oh, and in case you'd like to know how to find this hidden gem again--short of searching through pages of posts as I had to do--here's how to find it:
1) On the VGL Home page, on the left under Welcome and LogIn, click on "Services."
2) Click on the "Cattle" tile, far left on the second row.
3) On the first test, "Parentage/Genetic Marker Report," click on the "i" under Info. Here's a screen shot:
I'm sure some of you already know how to find this stuff, but if someone hadn't walked me through it, I'd never have found it! Now that you know how to find it, there are plenty of other good explanations on that page. Have fun clicking on "i's"!
I shared the link at the time, but it got rather lost at the end of a long discussion. I just shared it again, but in a thread about A&M, so anyone looking for it would never find it. With that in mind I thought I would share the link in its own thread so someone has a chance of finding it again.
Parentage Testing in Animal Pedigree Verification If you read far enough down in the article, it explains how the sire's and dam's genotypes are used to match with the calf's and gives some examples. I think the person I talked to on the phone explained "mating exclusion" MUCH better than the article does (part II). However, the final paragraph is very interesting:
In the majority of cases, if all available microsatellite markers are utilized, one parent will be positively excluded from the mating. However, the outcome of a mating exclusion case can change significantly if only one parent is provided. In this case without knowledge of the dam?s [sic] genetic contribution, both sire 1 and 4 would appear to qualify as a parent, which demonstrates the importance of providing both a dam and sire in a parentage case.
I thought the final section on Accuracy was also very interesting, especially the final paragraph:
Finally, it is important to remember that while parentage exclusions are 100% accurate parentage qualifications are not. The accuracy of most animal parentage tests is greater than 99% when both parents are included in the analysis and drops to around 95% when only one parent is included in the analysis. However, this accuracy will decrease when the potential parents are part of a large group of closely related animals. Again, an animal closely related to an actual parent could possess marker alleles that make it appear to be the correct parent. To prevent erroneous parentage qualifications, breeders need to submit samples from all possible parents when first requesting parentage verification. If more than one sire and one dam qualify as parents of an offspring the laboratory can then test with additional DNA markers to sort out the actual parents.
Oh, and in case you'd like to know how to find this hidden gem again--short of searching through pages of posts as I had to do--here's how to find it:
1) On the VGL Home page, on the left under Welcome and LogIn, click on "Services."
2) Click on the "Cattle" tile, far left on the second row.
3) On the first test, "Parentage/Genetic Marker Report," click on the "i" under Info. Here's a screen shot:
I'm sure some of you already know how to find this stuff, but if someone hadn't walked me through it, I'd never have found it! Now that you know how to find it, there are plenty of other good explanations on that page. Have fun clicking on "i's"!