There is a certain occurrence in genetic genealogy called a Non-Paternal or Non Paternity Event. This is a break in the ancestry of a person’s Y chromosome and surname. A person named “Smith,” for instance, might have a Y chromosome that is clearly “Johnson.”
A non paternal event can occur when an adopted male takes the surname of his adoptive family, or a male child takes his step-father’s surname, or a male child takes his mother’s surname (undoubtedly there are other circumstances as well).
When a break in the Y chromosome is suspected or confirmed, it is possible that the break might have occurred 1,000 years ago, 100 years ago, or with the testee’s birth.
An article in The Atlantic titled “Who’s Your Daddy” addresses the ‘unintended consequences of genetic screening for disease.’ Or, in some cases, the unintended consequences of testing for genetic genealogy. The author, Steve Olson, recently underwent genetic genealogy testing:
“A scientific officer at a genetic testing company knew that I was interested in genealogy, and he had offered to run my DNA through a sequencer. A few weeks earlier, I’d swished mouthwash inside my cheeks, sealed the mouthwash in a tube, and mailed the tube to the company.”
The results of Mr. Olson’s (when I say that name out loud, all I can think of is ‘Little House on the Prairie’!) test revealed that his DNA was what he predicted it would be – of Scandinavian descent.
However, as Mr. Olson points out, this doesn’t always happen. The article cites Bennett Greenspan, of Family Tree DNA, as stating that “any project that has more than 20 or 30 people in it is likely to have an oops in it.” This aligns well with the traditional belief that anywhere from 5 to 15% of men are not the actual biological fathers of their children. Following this out 10 generations, there is a 40% chance of a non-paternal event!
Along the same lines, a recent article was published on the Wall Street Journals ‘informedreader’ blog titled “As DNA Tests Spread, So Do Nasty Paternity Surprises.” The article cited Steve Olson’s piece in The Atlantic.
I must admit, I have a deep understanding of this issue and the effect it can have on tested individuals. I have a solid paper trail to Germany back to the 1750’s, but when I received the results of my test, I was shocked to find that my DNA belonged to a small and unique subclade of R1b1c that was only found in England! All of my closest matches also originated in the British Isles.
My first thought was a non-paternal event. I even asked my Mom whether my dad was actually my dad (I was 99.9% joking, of course)! I was so proud of my German heritage, and here I was faced with the possibility that I wasn’t German at all.
However, after a few months, new results showed that other people belonging to the unique subclade of R1b1c also originated in the same area of Germany that my ancestors came from. Thus, rather than worrying about a potential non-paternal event, I was the first person identified with this subclade to be from Germany.
Thanks to Hsien at EyeonDNA for her help!
DNA Genealogy etiketine sahip kayıtlar gösteriliyor. Tüm kayıtları göster
DNA Genealogy etiketine sahip kayıtlar gösteriliyor. Tüm kayıtları göster
11 Mart 2008 Salı
The Early Stages of the Genetic Genealogy Revolution
It’s always been my belief that personal genetics (inexpensive whole-genome analysis) will bring about some exciting changes in the field of genetic genealogy. One of the biggest areas of change will undoubtedly be in the area of autosomal genetic testing. (Remember that autosomal testing examines nuclear DNA, which is DNA other than mtDNA, Y-DNA, or X chromsomes).
A new study takes one of the first steps in the genetic genealogy revolution by examining SNP variations in four self-identified American populations – European, Latino/Hispanic, Asian, and African American (see reference below). “These population labels were used, despite the controversy surrounding the correspondence between notions of race and population structure inferred from explicit genetic data, because they are the labels used by NIH, FDA, and many, if not most, biomedical researchers.” The researchers sequenced the exons and flanking regions of 3,873 genes from 76 unrelated individuals.
Results:
SNPs common in one population were frequently not common in other populations. “Moreover, SNPs that were common in two or more populations often differed significantly in frequency from one another, particularly in comparisons of African Americans versus other U.S. populations. These findings indicate that even if the bulk of alleles underlying complex health-related traits are common SNPs, geographic ancestry might well be an important predictor of whether a person carries a risk allele. “
“A frequent claim about human population structure is that most common variation is shared among all populations. This, of course, depends on how population boundaries are defined, but often cited to support such comments are the comparisons of SNP frequencies in pairs of populations in the HapMap data and the Perlegen data. Analyses of these data indicated that common SNPs were frequently both shared and common among populations of predominately African, Asian, and European ancestry. However, population genetic analysis was not the intended goal of either the HapMap or the Perlegen projects, and common, shared SNPs were over sampled by the ascertainment strategies used for each project.”
The structure of common SNP variation differed substantially in African Americans compared with all other U.S. populations studied. “The largest absolute number of SNPs, common SNPs, and private SNPs were found in African Americans. African Americans exhibited the highest proportion of rare SNPs (64%), the lowest proportion of common SNPs (36%), and nearly half of all SNPs (44%) in African Americans were private.”
Although I still think it is too early for useful autosomal testing, this type of data suggests that there is a bright future for geographic ancestry.
Reference: The Structure of Common Genetic Variation in U.S. Populations. Stephen L. Guthery, Benjamin A. Salisbury, Manish S. Pungliya, J. Claiborne Stephens, and Michael Bamshad. The American Society of Human Genetics (Link(pdf, requires subscription)).
HT: Dienekes’ Anthropology Blog
A new study takes one of the first steps in the genetic genealogy revolution by examining SNP variations in four self-identified American populations – European, Latino/Hispanic, Asian, and African American (see reference below). “These population labels were used, despite the controversy surrounding the correspondence between notions of race and population structure inferred from explicit genetic data, because they are the labels used by NIH, FDA, and many, if not most, biomedical researchers.” The researchers sequenced the exons and flanking regions of 3,873 genes from 76 unrelated individuals.
Results:
SNPs common in one population were frequently not common in other populations. “Moreover, SNPs that were common in two or more populations often differed significantly in frequency from one another, particularly in comparisons of African Americans versus other U.S. populations. These findings indicate that even if the bulk of alleles underlying complex health-related traits are common SNPs, geographic ancestry might well be an important predictor of whether a person carries a risk allele. “
“A frequent claim about human population structure is that most common variation is shared among all populations. This, of course, depends on how population boundaries are defined, but often cited to support such comments are the comparisons of SNP frequencies in pairs of populations in the HapMap data and the Perlegen data. Analyses of these data indicated that common SNPs were frequently both shared and common among populations of predominately African, Asian, and European ancestry. However, population genetic analysis was not the intended goal of either the HapMap or the Perlegen projects, and common, shared SNPs were over sampled by the ascertainment strategies used for each project.”
The structure of common SNP variation differed substantially in African Americans compared with all other U.S. populations studied. “The largest absolute number of SNPs, common SNPs, and private SNPs were found in African Americans. African Americans exhibited the highest proportion of rare SNPs (64%), the lowest proportion of common SNPs (36%), and nearly half of all SNPs (44%) in African Americans were private.”
Although I still think it is too early for useful autosomal testing, this type of data suggests that there is a bright future for geographic ancestry.
Reference: The Structure of Common Genetic Variation in U.S. Populations. Stephen L. Guthery, Benjamin A. Salisbury, Manish S. Pungliya, J. Claiborne Stephens, and Michael Bamshad. The American Society of Human Genetics (Link(pdf, requires subscription)).
HT: Dienekes’ Anthropology Blog
J. Craig Venter and Personal Genetics
Wow, what a day for personal genetics. Yesterday, J. Craig Venter’s diploid genome was released (I’m not sure where the sequence is, but the paper is available at PLoS Biology, a OPEN ACCESS journal!).
I know that many people have their gripe about Venter, but seeing a story about personal genetics on the front page of CNN is important. It educates people and helps alleviate fears about genomic sequencing. I think it’s a great opportunity for the field. Here’s a few quotes from the CNN story:
“Venter has just published almost all 6 billion letters, or 96 percent, of his own personal genetic code in the journal PLoS Biology. From diseases to personality traits, it’s the most comprehensive human genome to date. Venter’s gene map provides a new understanding of his genetic destiny, according to the DNA inherited from both his father and his mother.
Venter says it’s just the beginning of a new era of personal genomics. “For the first time, we can answer almost any question of what’s genetic, what’s the environment. Our genes can tell us probabilities of what might happen and give us a chance to do something about it.”
There are also some quotes from George Church, leader of the Personal Genome Project:
“Dr. George Church, a professor of genetics at Harvard Medical School, is working on a DNA test that would identify for the consumer 1 percent of his or her DNA at a cost of $1,000. He says that someday soon, people may be checking their DNA maps as they do their stock portfolios — constantly adjusting to everyday developments and new gene discoveries.
“You’ll have all that information sitting at your desk and as the information flows in you’ll say, ‘I only want to know things of certain type. I don’t want to know about Alzheimer’s, or I don’t want to know about heart disease, or I do, or I want to know about everything, as soon as it comes in,” says Church.
It’s a habit Venter already follows. As more genes are discovered, he says, he constantly checks his own genome.”
For all the genetic genealogists out there, our habit will undoubtedly be comparing our genomes in order to find or identify potential relatives. Sure, curing disease and improving health is important, but genealogy is FUN!
The DNA Network has provided LOTS of coverage of the diploid genome release, so check out the following:
EyeonDNA, here and here.
Bitesizebio
SNPedia
Discovering Biology in a Digital World
evolgen
Genomicron
Scienceroll
The Genealogue (not a member of the DNA Network).
Whew, that should keep you busy for a while!!
I know that many people have their gripe about Venter, but seeing a story about personal genetics on the front page of CNN is important. It educates people and helps alleviate fears about genomic sequencing. I think it’s a great opportunity for the field. Here’s a few quotes from the CNN story:
“Venter has just published almost all 6 billion letters, or 96 percent, of his own personal genetic code in the journal PLoS Biology. From diseases to personality traits, it’s the most comprehensive human genome to date. Venter’s gene map provides a new understanding of his genetic destiny, according to the DNA inherited from both his father and his mother.
Venter says it’s just the beginning of a new era of personal genomics. “For the first time, we can answer almost any question of what’s genetic, what’s the environment. Our genes can tell us probabilities of what might happen and give us a chance to do something about it.”
There are also some quotes from George Church, leader of the Personal Genome Project:
“Dr. George Church, a professor of genetics at Harvard Medical School, is working on a DNA test that would identify for the consumer 1 percent of his or her DNA at a cost of $1,000. He says that someday soon, people may be checking their DNA maps as they do their stock portfolios — constantly adjusting to everyday developments and new gene discoveries.
“You’ll have all that information sitting at your desk and as the information flows in you’ll say, ‘I only want to know things of certain type. I don’t want to know about Alzheimer’s, or I don’t want to know about heart disease, or I do, or I want to know about everything, as soon as it comes in,” says Church.
It’s a habit Venter already follows. As more genes are discovered, he says, he constantly checks his own genome.”
For all the genetic genealogists out there, our habit will undoubtedly be comparing our genomes in order to find or identify potential relatives. Sure, curing disease and improving health is important, but genealogy is FUN!
The DNA Network has provided LOTS of coverage of the diploid genome release, so check out the following:
EyeonDNA, here and here.
Bitesizebio
SNPedia
Discovering Biology in a Digital World
evolgen
Genomicron
Scienceroll
The Genealogue (not a member of the DNA Network).
Whew, that should keep you busy for a while!!
DNA Genealogy
The next time you are watching your favorite CSI TV show or a particular movie and stumble into the fascinating world of DNA, you might be surprised to know that our DNA can do more than identify a suspect or victim at a crime scene. In fact, DNA is now being used to identify ancestors in the new and exciting field of DNA Genealogy.
DNA Genealogy takes traditional genealogy and applies genetics to it. DNA Genealogy involves the use of genealogical DNA testing to determine the level of genetic relationship between two individuals (Genealogical 2005). DNA, deoxyribonucleic acid, is used in the process because of its unique nature and the fact that it is passed down from one generation to the next. In the passing, some parts of the DNA remain almost completely unchanged, while other parts change dramatically. This property allows for the identification of certain consistencies between generations and provides the ability to identify genetic relationships.
There are two types of DNA tests available for testing DNA Genealogy: Mitochondrial DNA (mtDNA) and Y-chromosome DNA tests.
Mitochondrial DNA (mtDNA) is found in the cytoplasm of the cell instead of in the nucleus as is Y-chromosome (Tracing 2003). mtDNA is passed by a mother to both her male and female children without any additions or mixing from the father. Therefore, your mtDNA is the same as your mother’s mtDNA. mtDNA is different in nature compared to Y-DNA. It changes slowly making it more difficult to determine close relationships and easier to determine relatedness. If two people have the same mtDNA, there is a very good chance that they also share a common maternal ancestor. Unfortunately, it is difficult to determine if that common maternal ancestor was recent or instead lived hundreds of years ago.
Y-chromosome tests have been used more and more recently to determine DNA Genealogy. The Y-DNA tests are only available for males, because the Y-chromosome is only passed down along the paternal line from father to son. There are tiny chemical markers on the Y-chromosome that create a unique pattern. This pattern of markers is what is called a haplotype. A haplotype is used to determine one male lineage from another. This type of testing is often used to determine if two individuals who have the same surname share a common ancestor.
One of the early beginnings of DNA Genealogy was a study published by Bryan Sykes in 2000 (Sykes and Irven 2000) that used DNA Genealogy (Y-chromosome markers) along with surname studies to determine relatedness. The study compared 48 men with the same surname of Sykes from the regions of England and analyzed four Short Tandem Repeats (STRs) on their Y-chromosome: DYS19, DYS390, DYS391, and DYS393. The study found that of the 48 men tested, 21 had the same core haplotype and many others were only one mutational step away from the core haplotype. Skypes interpreted these results to reveal a common origin from an ancestor who lived some 700 years ago (Butler 2005).
Since its early beginnings, DNA Genealogy has come a long way and has grown rapidly. DNA Genealogy continues to increase in popularity as the price of tests becomes much more affordable and the number of markers and clarity of the tests become greater. Additionally, DNA collection techniques make it a very simple and pain-free process.
Sources
Butler J. (2005) Forensic DNA Typing; Biology, Technology, and Genetics of STR Markers, 74, 231-232.
Genealogical DNA test. (2005, December 7). Wikipedia, The Free Encyclopedia. Retrieved 21:52, December 8, 2005 from http://en.wikipedia.org/w/index.php?title=Genealogical_DNA_test&oldid=30489865.
Sykes, B. and Irven, C. (2000) American Journal of Human Genetics, 66, 1417-1419.
DNA Genealogy takes traditional genealogy and applies genetics to it. DNA Genealogy involves the use of genealogical DNA testing to determine the level of genetic relationship between two individuals (Genealogical 2005). DNA, deoxyribonucleic acid, is used in the process because of its unique nature and the fact that it is passed down from one generation to the next. In the passing, some parts of the DNA remain almost completely unchanged, while other parts change dramatically. This property allows for the identification of certain consistencies between generations and provides the ability to identify genetic relationships.
There are two types of DNA tests available for testing DNA Genealogy: Mitochondrial DNA (mtDNA) and Y-chromosome DNA tests.
Mitochondrial DNA (mtDNA) is found in the cytoplasm of the cell instead of in the nucleus as is Y-chromosome (Tracing 2003). mtDNA is passed by a mother to both her male and female children without any additions or mixing from the father. Therefore, your mtDNA is the same as your mother’s mtDNA. mtDNA is different in nature compared to Y-DNA. It changes slowly making it more difficult to determine close relationships and easier to determine relatedness. If two people have the same mtDNA, there is a very good chance that they also share a common maternal ancestor. Unfortunately, it is difficult to determine if that common maternal ancestor was recent or instead lived hundreds of years ago.
Y-chromosome tests have been used more and more recently to determine DNA Genealogy. The Y-DNA tests are only available for males, because the Y-chromosome is only passed down along the paternal line from father to son. There are tiny chemical markers on the Y-chromosome that create a unique pattern. This pattern of markers is what is called a haplotype. A haplotype is used to determine one male lineage from another. This type of testing is often used to determine if two individuals who have the same surname share a common ancestor.
One of the early beginnings of DNA Genealogy was a study published by Bryan Sykes in 2000 (Sykes and Irven 2000) that used DNA Genealogy (Y-chromosome markers) along with surname studies to determine relatedness. The study compared 48 men with the same surname of Sykes from the regions of England and analyzed four Short Tandem Repeats (STRs) on their Y-chromosome: DYS19, DYS390, DYS391, and DYS393. The study found that of the 48 men tested, 21 had the same core haplotype and many others were only one mutational step away from the core haplotype. Skypes interpreted these results to reveal a common origin from an ancestor who lived some 700 years ago (Butler 2005).
Since its early beginnings, DNA Genealogy has come a long way and has grown rapidly. DNA Genealogy continues to increase in popularity as the price of tests becomes much more affordable and the number of markers and clarity of the tests become greater. Additionally, DNA collection techniques make it a very simple and pain-free process.
Sources
Butler J. (2005) Forensic DNA Typing; Biology, Technology, and Genetics of STR Markers, 74, 231-232.
Genealogical DNA test. (2005, December 7). Wikipedia, The Free Encyclopedia. Retrieved 21:52, December 8, 2005 from http://en.wikipedia.org/w/index.php?title=Genealogical_DNA_test&oldid=30489865.
Sykes, B. and Irven, C. (2000) American Journal of Human Genetics, 66, 1417-1419.
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