DNA for Newbies

In the past decade, scientists have repeatedly referred to ‘Mitochondrial Eve‘, the (hypothesized) source of mtDNA for all humans alive today.  She is believed to have lived approximately 140,000 years ago in Africa.  There is also ‘Y-chromosomal Adam‘, the (hypothesized) source of every living man’s Y-DNA.  He is also believed to have lived in Africa, but more recently, between 60,000 and 90,000 years ago.  Thus, Mitochondrial Eve and Y-chromsomal Adam were not a couple – they were not the source of all human genetic material on the planet today.  Instead, the terms refer to the founders of all the mtDNA and Y-DNA respectively.

For a wonderful description of some of the genetic behind Mitochondrial Eve and Y-chromsomal Adam, go to “The Questionable Authority“, a blog which is part of Scienceblogs.  While you’re there, be sure to read the comments, where the discussion addresses the time disparity between the two DNA sources (140,000 years ago versus 60-90,000 years ago). ... Click to read more!

Often, at least at the current stage of genetic genealogy, DNA sequencing does not reveal enough information to identify a person’s particular Y chromosome or mtDNA haplogroup.The example I will be using in this post is Haplogroup E.Haplogroup E split into E1, E2, and E3 about 28,000 years ago.Current tests offered by many sequencing companies are able to place a person in the general “E” Haplogroup, but might be unable to determine exactly which subclade of E a person descends from.In such a situation, a “Deep SNP” test can be used to fill in that information.

A SNP is single nucleotide polymorphism, or a change in the DNA sequence at a single nucleotide.For instance, the switch of a C for G, a cytosine for a guanine.You can see a chart of some of the most common SNPs tested for genetic genealogy here or here.The Deep SNP test (which can go by other names) analyzes a person’s DNA, such as the Y chromosome, for the presence or lack of these mutation(s). ... Click to read more!

Do you have a burning question about genetics that’s been keeping you up at night? Ever wonder why the combination of red hair and brown eyes is so rare? There are two great resources currently available online for anyone who is curious about genetics.

AsktheGeneticist is a partnership between the Department of Human Genetics at Emory University and theDepartment of Genetics at the University of Alabama at Birmingham.The mission of AsktheGeneticist “is to answer questions about genetic concepts, and the etiology, treatment, research, testing, and predisposition to genetic disorders.” AsktheGeneticist has a genetic genealogy section, but it’s pretty sparse.

The Tech Museum of Innovation in San Jose, California has partnered with the Department of Genetics at Stanford University to present “Genetics: Technology with a Twist.”The interactive site has an ‘Ask The Geneticist’ section where you can ask a Stanford geneticist a question. ... Click to read more!

1.You got those big blue eyes from your grandmother, but chances are you inherited less desirable genes as well.We inherit our DNA from our parents, who inherited it from their parents.Since we all possess genes that can cause or contribute to disease, knowing one’s DNA and family medical history can be a great resource for someone who learns they have a genetic disorder.

2.Full genome sequencing is right around the corner!The X-prize quest for the $1000 genome will lead to efficient and affordable whole-genome sequencing.As commercial companies crop up and compete for customer’s business, leading to even lower prices.

3.Your grandmother’s DNA contains clues to her ancestry.X-chromosome, mtDNA, and autosomal genealogy tests contain clues to a person’s ancestry, both recent and ancient. ... Click to read more!

If you’re a regular reader of this blog, then you know that I am a strong proponent of genetic testing for genealogical purposes.I believe that when used correctly genetic testing can serve as a valuable tool in the genealogist’s toolbox.

A recent visitor found my blog with the search term “is genetic genealogy a scam?”When I recreated the search, I discovered that a previous post on this blog is the leading link for this search. The process made me think about the many people who are skeptical or wary of genetic genealogy.As a scientist, I appreciate and encourage healthy skepticism.After all, genetic genealogy has been available for less than a decade, and it has changed considerably since it was first offered.I believe that anyone who forays into the world of genetic genealogy should have a basic understanding of the science and the application of the results.Just reading about genetic genealogy in the media can give one a distorted view of the technology.Along this point, I recommend reading an interesting article by Rebecca Skloot (author of the upcoming book “The Immortal Life of Henrietta Lacks,” which I can’t wait to read).I was referred to that article by a post on her blog (Culture Dish) entitled “The Bogus-ness of DNA Testing for Genealogy Research” in which she reiterates the point that genetic genealogy tests “simply can’t tell you anything definitive about your heredity unless you’re testing your DNA and comparing it to someone else’s to find out if you’re related.” ... Click to read more!