Last week I wrote about the results of my Family Finder autosomal DNA test by Family Tree DNA (see “A Review of Family Tree DNA’s Family Finder – Part I“). The Family Finder test uses a whole-genome SNP scan to find stretches of DNA shared by two individuals, thus identifying your genetic cousins (and will soon include the Population Finder analysis of admixture percentages). I currently have over 33 genetic cousins in Family Finder, and I’m working with them to identify our common ancestor(s).
The Affymetrix microarray chip used by FTDNA includes over 500,000 pairs of SNPs located on the X chromosome and the autosomes (no Y chromosome SNPs). Via SNPedia:
FamilyTreeDNA uses an Affymetrix Axiom CEU microarray chip with 3,269 SNPs removed (563,800 SNPs reported) for autosomal and X (but not Y or mitochondrial) ancestry testing for $289. Other sources have cited 548011 snps. This platform tests 1871 of the 12442 snps in SNPedia.
Mary Carmichael, a science editor for Newsweek, is in the midst of aweek-long dilemma. This Friday, after reading a series of articles written by members of the DTC genetic testing community, she will decide whether she should purchase a genome-wide SNP analysis. Although the decision might be a simple one for some, in light of the recent critique of DTC genetic testing in the media, in the literature, and by the government, it is certainly understandable that Mary is looking for further insight into her decision.
Today, Mary is asking “What Can I Learn From At-Home DNA Tests?” and has gathered answers to her question from a wide variety of writers and scientists, including myself. Since the Newsweek site only has space for a brief introduction to each topic, this post is meant to be a more in-depth answer what Mary could learn about her ancestry from a DTC test.
Since late 2007, several “direct-to-consumer” or “DTC” genetic testing products have entered the marketplace, many of which offered some degree of autosomal ancestry analysis (including 23andMe, deCODEme, and Pathway Genomics, among others).
On May 6, 2010, the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany presented the world with a draft of the genome sequence of the Neanderthal (press release here (pdf) and full article here (free), NYT article here). As part of the announcement, the team presented their conclusion that 1% to 4% of the genome of non-Africans is derived from Neanderthals:
“An initial comparison of the two sequences has brought some exciting discoveries to light. Contrary to the assumption of many researchers, it would appear that some Neandertals and early modern humans interbred. According to the researchers’ calculations, between one and four percent of the DNA of many humans living today originate from the Neandertal. ‘Those of us who live outside Africa carry a little Neandertal DNA in us,’ says Svante Pääbo. Previous tests carried out on the DNA of Neandertal mitochondria, which represents just a tiny part of the whole genome, had not found any evidence of such interbreeding or ‘admixture.'”
This paper is a follow-up to a 2008 paper called the “ASHG Ancestry Testing Statement and Recommendations” in which a committee from the ASHG addressed concerns about the claims made by genetic ancestry testing companies. I wrote an article here on the blog at the time – The ASHG Ancestry Testing Statement and Recommendations – that highlighted a number of concerns I had about the statement and the recommendations.
When I wrote the November 13, 2008 blog post, I began by pointing out my personal positions, which have largely remained unchanged in the intervening 1.5 years:
In my genealogical research, I have sometimes found myself missing the trees by focusing on the forest.Â I think it happens to many genealogists â€“ we get caught up in the research, the dates, the places, and we forget that there was so much more to people than their vital statistics.
This can happen to genetic genealogists as well.Â The connection between the results of a DNA test and the individuals in our tree can be easy to forget and difficult to visualize.Â Take the results of an mtDNA test, for example.Â The results are obtained from a tiny piece of DNA that has traveled thousands of years (and often thousands of miles) through hundreds of individuals to end up in your cheek cells and on the tip of a swab.Â Everyoneâ€™s mtDNA is the product of an amazingly rich story that has largely been lost to history.
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GeneTree’s comprehensive new service offering focuses on integrating two essential sources of human identity: quality genetic tests and industry-standard family history consulting services. In contrast to providers that focus exclusively on anthropological deep ancestry, GeneTree’s product and service offering is designed to help people discover near-term family connections in the last six to ten generations as well as deep ancestral connections.
Randy Seaver at Genea-Musings (â€œI’m Puzzled by DNA Claims on â€˜Faces of Americaâ€™â€) writes about the fourth and last episode of â€œFaces of America,â€ a PBS documentary series investigating the ancestry of several famous people in America. This fourth episode included several different types of genetic genealogy to examine the ancestral origins and relatedness of the showâ€™s members.
1. Whole Genome Sequencing by Knome
The first type of genetic genealogy was whole-genome sequencing by Knome of Henry Louis Gates and his father. This analysis examined Henryâ€™s (â€œSkipâ€™sâ€) genome for medical conditions and physical traits, and also compared his DNA to his fatherâ€™s, thereby allowing them to deduce the entire DNA contribution from his deceased mother. This segment was actually quite moving, as Dr. Gates was able to establish this intimate connection to the mother that he and his father obviously missed very much.