مهمان عزیز به کتابخانه الکترونیکی آریا خوش آمدید برای دانلود کتاب های الکترونیکی رایگان و کتاب های صوتی و مخصوص موبایل در سایت عضو شوید
10 DNA Myths Busted
DNA Testing Myths Busted, and Other Favorite Posts
By Blaine T. Bettinger
Blaine Bettinger is the author of The Genetic Genealogist.
He has been using traditional genealogical research for
almost 20 years and is interested in the intersection of
genealogy and DNA Testing. In 2006 he received his Ph.D.
in biochemistry with a concentration in genetics. He is
currently a second-year law student
Blaine Bettinger is the author of The Genetic Genealogist.
He has been using traditional genealogical research for
almost 20 years and is interested in the intersection of
genealogy and DNA Testing. In 2006 he received his Ph.D.
in biochemistry with a concentration in genetics. He is
currently a second-year law student
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 1
© 2007 Blaine T. Bettinger, Ph.D. Please feel free to post, email, or print this ebook for any non-commercial purpose. Not for resale.
--------------------------------------- 2
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 2
10 DNA Testing Myths Busted
(Originally posted October 25, 2007)
1. Genetic genealogy is only for hardcore
genealogists.
Wrong! If you’ve ever wondered about the origins of
your DNA, or about your direct paternal or maternal
ancestral line, then genetic genealogy might be an
interesting way to learn more. Although DNA testing
of a single line, such as through an mtDNA test, will only examine one ancestor out of 1024 potential ancestors at 10
generations ago, this is a 100% improvement over 0 ancestors out of 1024. If you add your father’s Y-DNA, this is a
200% improvement. Now add your mother’s mtDNA, and so on. However, please note the next myth:
2. I’m going to send in my DNA sample and get back my entire family tree.
Sorry. DNA alone cannot tell a person who their great-grandmother was, or what Italian village their great-great
grandfather came from. Genetic genealogy can be an informative and exciting addition to traditional research, and can
sometimes be used to answer specific genealogical mysteries.
3. I would like to try genetic genealogy, but I’m terrified of needles.
Good news! Genetic genealogy firms don’t use blood samples to collect cells for DNA testing. Instead, these companies
send swabs or other means to gently obtain cells from the cheek and saliva.
4. I would like to test my ancestor’s DNA, but they died years ago.
You don’t always need your ancestor’s DNA to get useful information from a genetic genealogy test. If you are male,
you contain the Y-chromosome (Y-DNA) that was given to you by your father, who received it from his father, and so
on. Both males and females have mitochondrial DNA (mtDNA), which was passed on to them by their mother, who
--------------------------------------- 3
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 3
received it from her mother, and so on. Everyone of us contains DNA (Y-DNA and/or mtDNA) from our ancestors that
can be studied by genetic genealogy.
5. I want to test my mother’s father’s Y-DNA, but since he didn’t pass on his Y-chromosome to my
mother, I’m out of luck.
Wrong! There is a very good chance that there is another source of that same Y-DNA. For instance, does your mother
have a brother (your uncle) who inherited the Y-DNA from his father? Or does your mother’s father have a brother
(your great-uncle) who would be willing to submit DNA for the test? Sometimes there might not be an obvious source
of “lost” Y-DNA, or no one in the family is willing to take a DNA test. The secret to solving this problem is to do what
every good genealogist does – use traditional genealogical research (paper records, census information, etc) to “trace
the DNA”. Follow the line back while tracing descendants in order to find someone who is interested in learning more
about their Y-DNA. This applies to finding a source of mtDNA as well.
6. Only men can submit DNA for genetic genealogy tests, since women do not have the Y-chromosome.
Wrong! Most genetic genealogy testing companies also offer mtDNA testing. Both men and women have mtDNA in
their cells and can submit that DNA for testing. In addition, women can test their father’s or some other male relative’s
Y-DNA to learn more about their paternal ancestral line, even though they did not inherit the Y-chromosome.
7. My genetic genealogy test will also reveal my propensity for diseases associated with the Y-
chromosome and mtDNA.
Wrong, thank goodness. Most of the information obtained by genetic genealogy tests has no known medical relevancy,
and these firms are not actively looking for medical information. It is important to note, however, that some medical
information (such as infertility detected by DYS464 testing or other diseases detectable by a full mtDNA sequence)
might inadvertently be revealed by a genetic genealogy test.
8. I don’t like the thought of a company having my DNA on file or my losing control over my DNA sample.
This is, of course, an understandable concern. However, most testing firms give a client two options: the DNA is either
immediately destroyed once the tests are run, or it is securely stored for future testing. If the DNA is stored, the firm
--------------------------------------- 4
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 4
will typically destroy the DNA upon request. If the long-term storage of DNA is a concern, be sure to research the
company’s policy before sending in a sample.
9. If my test reveals Native American ancestry, I plan to join a particular Native American affiliation
group.
Although genetic genealogy can potentially reveal Native American ancestry (for instance, my mtDNA belongs to the
Native American haplogroup A2), it is incredibly unlikely that this information will be sufficient to positively identify
the specific source of the lineage (such as a tribe) or allow membership in a particular Native American affiliation.
10. My DNA is so boring that genetic genealogy would be a waste of time and money.
Very wrong! A person’s DNA is a very special possession – although everyone has DNA, everyone’s DNA is different
(okay, except identical twins – if your identical twin has been tested, you should think twice about buying the same
test!). As humans settled the world, Y-DNA and mtDNA spread and mixed randomly. As a result, it is impossible to
guess with 100% assurance that a person’s Y-DNA or mtDNA belongs to a particular haplogroup (a related family of
DNA sequences) without DNA testing.
BONUS MYTH: My genetic genealogy test says that my mtDNA belongs to Haplogroup A2. Juanita the Ice
Maiden, a frozen mummy discovered in the Andes Mountains in Peru, also has Haplogroup A2 mtDNA.
Therefore, she must be my ancestor!
Unfortunately, although genetic genealogy can reveal that a person is RELATED to an ancient DNA source, it cannot prove
that a person is a DESCENDANT of an ancient DNA source. For instance, perhaps you are descended from Juanita’s
sister, or her 5th cousin. Thus, although Juanita might be your great-great-great-great…great-grandmother, she might
instead be your great-great-great-great…great-aunt. And since Juanita died when she was just 12 to 14, it is unlikely she
has any descendants.
If you understand the risks associated with genetic genealogy (such as the detection of non-paternal events) and other
risks) and are ready and willing to embrace the results to learn more about your genetic ancestry, then genetic genealogy
might be for you. I recommend that you read archived posts here at The Genetic Genealogist, and do some online research
through one of the many companies that offer genetic genealogy testing
--------------------------------------- 5
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 5
To Sequence or Not to Sequence - That is the Question
(Originally posted October 15, 2007)
An article appearing Sunday at Bloomberg.com, “Cheap,
Detailed Genetic Testing Might Soon Be Ready for Market“,
highlights some of the recent developments in DNA
sequencing. The article is a response to three studies
published at Nature Methods which reportedly “explore
cheap technologies to decipher and analyze individual
patients’ DNA by allowing researchers to quickly find the
small portions of the human genome that make protein and
describe them, while discarding irrelevant data.”
According to the author of the Bloomberg article,
“complete” DNA sequencing for as little as $300 could be
ready within months. Although it is unclear what the author
means by “complete”, it is entirely foreseeable that SNP testing will soon be available for a reasonable price.
All this leads to the question which is so hotly debated in the blogosphere - if inefficient
sequencing becomes available to the average consumer, should they get their genome
sequenced?
As the article points out, there are already around 1,000 different DNA sequencing tests which range in price from $200
to $3,000. However, Cathy Wicklund, the president of the National Society of Genetic Counselors, believes that people
should “think hard before asking for complete genome testing”:
“Just because we have the technology doesn’t necessarily mean that we should jump to offer it,” she said. “Consumers
should ask themselves, `What is this going to tell me, is it going to give me information that’s helpful right now?’ “
There are a number of strong voices in this arena, others who believe that genomic sequencing without further extensive
studies that link genotype and phenotype is useless and potentially harmful to any consumer who does not have a strong
--------------------------------------- 6
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 6
genetics background. Although I respect this position, I believe that attempting to ward people away from genomic
sequencing will prove to be ineffective. Genetics is about to leave the hands of the medical professional, and there’s
nothing we can (or perhaps should) do about it.
Fortunately or unfortunately, the wave is coming. In just months or a few short years, anyone will be able to open an
envelope or log into a website and see their entire genomic sequence, from the very first nucleotide to the very last. Thus
the question is not whether people should get their genome sequenced - because they invariably will - but
rather what can be done to educate consumers. With a background in genetics, I know better than many
consumers all the dangers that my genetic sequence will reveal. But I’ll still be ready to swab my cheeks the instant I can
afford a complete genomic sequence.
Is there really no proper place for the average non-geneticist, non-physician-assisted consumer in the whole genome
market? What if I can’t afford a genetic specialist - should I be denied the opportunity to sequence my genome? What if
my health insurer refuses to pay for genetic sequencing? Should only the knowledgeable or the rich be allowed to learn
more about their genes?
I would argue that there is a place for the “early consumer.” Early consumers are the pioneers, the curious who do
something because it is new and exciting and they want to learn more about the technology and about themselves. For
instance, there are so many people that get into genetic genealogy even though they don’t know the first thing about
genetics. When they get their results back, they do what the human mind was designed to do - they go out and attempt to
learn more (and helping educate them is exactly why I started The Genetic Genealogist in the first place). Luckily, there
are already others who are leading the consumer education front.
All new technology comes with risks. Even genetic genealogy, the sequencing of a few SNPs or a few 100 base pairs, can
reveal unexpected or unwanted results. But should the risks really cause so much fear and caution? We are who we are
regardless of whether or not we get sequenced. Sequencing just arms us with information that could, now or in the future,
be useful. For me, the benefits far outweigh the risks.
In my opinion, the answer is to educate, educate, educate. Convincing people that their genome is scary or useless will
dissuade very few from sequencing and will likely only alienate the pioneers.
--------------------------------------- 7
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 7
Top 5 Reasons to Save Your Grandmother’s DNA
(Originally posted May 10, 2007)
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.
4. Even if you aren’t interested in this whole genetic genealogy craze, somebody you know will be!
Genealogy is one of the most popular hobbies in America, and the use of DNA to augment traditional genealogical
research is growing faster than ever. Chances are that someone you know will someday be interested in your
grandmother’s DNA!
5. All the undiscovered possibilities. No one knows what uses will be discovered for DNA in the future. Save that
DNA just in case!
Disclaimer: Some people are very uncomfortable with the thought of gathering and storing a loved one’s DNA, and those
beliefs should be honored and respected. It is ALWAYS best to obtain your grandmother’s permission before you gather
her DNA. So don’t delay, call her now! &n
© 2007 Blaine T. Bettinger, Ph.D. Please feel free to post, email, or print this ebook for any non-commercial purpose. Not for resale.
--------------------------------------- 2
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 2
10 DNA Testing Myths Busted
(Originally posted October 25, 2007)
1. Genetic genealogy is only for hardcore
genealogists.
Wrong! If you’ve ever wondered about the origins of
your DNA, or about your direct paternal or maternal
ancestral line, then genetic genealogy might be an
interesting way to learn more. Although DNA testing
of a single line, such as through an mtDNA test, will only examine one ancestor out of 1024 potential ancestors at 10
generations ago, this is a 100% improvement over 0 ancestors out of 1024. If you add your father’s Y-DNA, this is a
200% improvement. Now add your mother’s mtDNA, and so on. However, please note the next myth:
2. I’m going to send in my DNA sample and get back my entire family tree.
Sorry. DNA alone cannot tell a person who their great-grandmother was, or what Italian village their great-great
grandfather came from. Genetic genealogy can be an informative and exciting addition to traditional research, and can
sometimes be used to answer specific genealogical mysteries.
3. I would like to try genetic genealogy, but I’m terrified of needles.
Good news! Genetic genealogy firms don’t use blood samples to collect cells for DNA testing. Instead, these companies
send swabs or other means to gently obtain cells from the cheek and saliva.
4. I would like to test my ancestor’s DNA, but they died years ago.
You don’t always need your ancestor’s DNA to get useful information from a genetic genealogy test. If you are male,
you contain the Y-chromosome (Y-DNA) that was given to you by your father, who received it from his father, and so
on. Both males and females have mitochondrial DNA (mtDNA), which was passed on to them by their mother, who
--------------------------------------- 3
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 3
received it from her mother, and so on. Everyone of us contains DNA (Y-DNA and/or mtDNA) from our ancestors that
can be studied by genetic genealogy.
5. I want to test my mother’s father’s Y-DNA, but since he didn’t pass on his Y-chromosome to my
mother, I’m out of luck.
Wrong! There is a very good chance that there is another source of that same Y-DNA. For instance, does your mother
have a brother (your uncle) who inherited the Y-DNA from his father? Or does your mother’s father have a brother
(your great-uncle) who would be willing to submit DNA for the test? Sometimes there might not be an obvious source
of “lost” Y-DNA, or no one in the family is willing to take a DNA test. The secret to solving this problem is to do what
every good genealogist does – use traditional genealogical research (paper records, census information, etc) to “trace
the DNA”. Follow the line back while tracing descendants in order to find someone who is interested in learning more
about their Y-DNA. This applies to finding a source of mtDNA as well.
6. Only men can submit DNA for genetic genealogy tests, since women do not have the Y-chromosome.
Wrong! Most genetic genealogy testing companies also offer mtDNA testing. Both men and women have mtDNA in
their cells and can submit that DNA for testing. In addition, women can test their father’s or some other male relative’s
Y-DNA to learn more about their paternal ancestral line, even though they did not inherit the Y-chromosome.
7. My genetic genealogy test will also reveal my propensity for diseases associated with the Y-
chromosome and mtDNA.
Wrong, thank goodness. Most of the information obtained by genetic genealogy tests has no known medical relevancy,
and these firms are not actively looking for medical information. It is important to note, however, that some medical
information (such as infertility detected by DYS464 testing or other diseases detectable by a full mtDNA sequence)
might inadvertently be revealed by a genetic genealogy test.
8. I don’t like the thought of a company having my DNA on file or my losing control over my DNA sample.
This is, of course, an understandable concern. However, most testing firms give a client two options: the DNA is either
immediately destroyed once the tests are run, or it is securely stored for future testing. If the DNA is stored, the firm
--------------------------------------- 4
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 4
will typically destroy the DNA upon request. If the long-term storage of DNA is a concern, be sure to research the
company’s policy before sending in a sample.
9. If my test reveals Native American ancestry, I plan to join a particular Native American affiliation
group.
Although genetic genealogy can potentially reveal Native American ancestry (for instance, my mtDNA belongs to the
Native American haplogroup A2), it is incredibly unlikely that this information will be sufficient to positively identify
the specific source of the lineage (such as a tribe) or allow membership in a particular Native American affiliation.
10. My DNA is so boring that genetic genealogy would be a waste of time and money.
Very wrong! A person’s DNA is a very special possession – although everyone has DNA, everyone’s DNA is different
(okay, except identical twins – if your identical twin has been tested, you should think twice about buying the same
test!). As humans settled the world, Y-DNA and mtDNA spread and mixed randomly. As a result, it is impossible to
guess with 100% assurance that a person’s Y-DNA or mtDNA belongs to a particular haplogroup (a related family of
DNA sequences) without DNA testing.
BONUS MYTH: My genetic genealogy test says that my mtDNA belongs to Haplogroup A2. Juanita the Ice
Maiden, a frozen mummy discovered in the Andes Mountains in Peru, also has Haplogroup A2 mtDNA.
Therefore, she must be my ancestor!
Unfortunately, although genetic genealogy can reveal that a person is RELATED to an ancient DNA source, it cannot prove
that a person is a DESCENDANT of an ancient DNA source. For instance, perhaps you are descended from Juanita’s
sister, or her 5th cousin. Thus, although Juanita might be your great-great-great-great…great-grandmother, she might
instead be your great-great-great-great…great-aunt. And since Juanita died when she was just 12 to 14, it is unlikely she
has any descendants.
If you understand the risks associated with genetic genealogy (such as the detection of non-paternal events) and other
risks) and are ready and willing to embrace the results to learn more about your genetic ancestry, then genetic genealogy
might be for you. I recommend that you read archived posts here at The Genetic Genealogist, and do some online research
through one of the many companies that offer genetic genealogy testing
--------------------------------------- 5
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 5
To Sequence or Not to Sequence - That is the Question
(Originally posted October 15, 2007)
An article appearing Sunday at Bloomberg.com, “Cheap,
Detailed Genetic Testing Might Soon Be Ready for Market“,
highlights some of the recent developments in DNA
sequencing. The article is a response to three studies
published at Nature Methods which reportedly “explore
cheap technologies to decipher and analyze individual
patients’ DNA by allowing researchers to quickly find the
small portions of the human genome that make protein and
describe them, while discarding irrelevant data.”
According to the author of the Bloomberg article,
“complete” DNA sequencing for as little as $300 could be
ready within months. Although it is unclear what the author
means by “complete”, it is entirely foreseeable that SNP testing will soon be available for a reasonable price.
All this leads to the question which is so hotly debated in the blogosphere - if inefficient
sequencing becomes available to the average consumer, should they get their genome
sequenced?
As the article points out, there are already around 1,000 different DNA sequencing tests which range in price from $200
to $3,000. However, Cathy Wicklund, the president of the National Society of Genetic Counselors, believes that people
should “think hard before asking for complete genome testing”:
“Just because we have the technology doesn’t necessarily mean that we should jump to offer it,” she said. “Consumers
should ask themselves, `What is this going to tell me, is it going to give me information that’s helpful right now?’ “
There are a number of strong voices in this arena, others who believe that genomic sequencing without further extensive
studies that link genotype and phenotype is useless and potentially harmful to any consumer who does not have a strong
--------------------------------------- 6
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 6
genetics background. Although I respect this position, I believe that attempting to ward people away from genomic
sequencing will prove to be ineffective. Genetics is about to leave the hands of the medical professional, and there’s
nothing we can (or perhaps should) do about it.
Fortunately or unfortunately, the wave is coming. In just months or a few short years, anyone will be able to open an
envelope or log into a website and see their entire genomic sequence, from the very first nucleotide to the very last. Thus
the question is not whether people should get their genome sequenced - because they invariably will - but
rather what can be done to educate consumers. With a background in genetics, I know better than many
consumers all the dangers that my genetic sequence will reveal. But I’ll still be ready to swab my cheeks the instant I can
afford a complete genomic sequence.
Is there really no proper place for the average non-geneticist, non-physician-assisted consumer in the whole genome
market? What if I can’t afford a genetic specialist - should I be denied the opportunity to sequence my genome? What if
my health insurer refuses to pay for genetic sequencing? Should only the knowledgeable or the rich be allowed to learn
more about their genes?
I would argue that there is a place for the “early consumer.” Early consumers are the pioneers, the curious who do
something because it is new and exciting and they want to learn more about the technology and about themselves. For
instance, there are so many people that get into genetic genealogy even though they don’t know the first thing about
genetics. When they get their results back, they do what the human mind was designed to do - they go out and attempt to
learn more (and helping educate them is exactly why I started The Genetic Genealogist in the first place). Luckily, there
are already others who are leading the consumer education front.
All new technology comes with risks. Even genetic genealogy, the sequencing of a few SNPs or a few 100 base pairs, can
reveal unexpected or unwanted results. But should the risks really cause so much fear and caution? We are who we are
regardless of whether or not we get sequenced. Sequencing just arms us with information that could, now or in the future,
be useful. For me, the benefits far outweigh the risks.
In my opinion, the answer is to educate, educate, educate. Convincing people that their genome is scary or useless will
dissuade very few from sequencing and will likely only alienate the pioneers.
--------------------------------------- 7
The Genetic Genealogist Blaine T. Bettinger, Ph.D. 7
Top 5 Reasons to Save Your Grandmother’s DNA
(Originally posted May 10, 2007)
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.
4. Even if you aren’t interested in this whole genetic genealogy craze, somebody you know will be!
Genealogy is one of the most popular hobbies in America, and the use of DNA to augment traditional genealogical
research is growing faster than ever. Chances are that someone you know will someday be interested in your
grandmother’s DNA!
5. All the undiscovered possibilities. No one knows what uses will be discovered for DNA in the future. Save that
DNA just in case!
Disclaimer: Some people are very uncomfortable with the thought of gathering and storing a loved one’s DNA, and those
beliefs should be honored and respected. It is ALWAYS best to obtain your grandmother’s permission before you gather
her DNA. So don’t delay, call her now! &n
منبع : کتابخانه آریا
