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  • We're more different than thought, genome map reveals

    We're more different than thought, genome map reveals

    Last Updated: Wednesday, November 22, 2006 | 1:50 PM ET

    CBC News

    A new genetic map written by an international research team has forced a fundamental rethink of how genes work and has already made a difference in diagnosing some genetic diseases.

    Stephen Scherer, a geneticist at the University of Toronto and the Hospital for Sick Children, and his colleagues found several hundred unusual mutations in a newly updated map of the human genome.

    The map was drawn up by analyzing DNA from 270 individuals from four populations with ancestry in Europe, Africa or Asia.

    "Now we know that our genomes are much more variable," said Scherer, whose study is in Thursday's issue of the journal Nature. "It changes the design of all of our studies. It really changes our understanding of ourselves in fact."

    The results of the study mean people are far more genetically variable than first thought. The new map shows genes don't always line up as expected — there can be mismatches, or chunks with missing or extra DNA.

    The mismatched genes and rogue chunks of DNA can cause profound and mysterious health problems that could explain some forms of autism, heart defects and Alzheimer's disease, researchers say.

    Genes usually occur in two copies, with one inherited from each parent. The researchers found about 2,900 genes, or more than 10 per cent of the human genome, had variations in the number of copies of specific DNA segments.
    Until now, research on genetic diseases has focused on small changes called single nucleotide polymorphisms, or SNPs.

    It may be that some diseases are instead caused by differences in the number of copies, and recent research suggests that's true for some types of kidney disease, Parkinson's disease, Alzheimer's and susceptibility to AIDS.

    Scherer's lab discovered a connection between pinched blood vessels and missing DNA.

    'Like a kink in a hose'

    Study co-author Martin Somerville, a professor of medical genetics at the University of Alberta, found six cases where a missing strand of DNA corresponds with an identical heart condition.

    "It's like a kink in a hose in a way of that main vessel," said Somerville.

    Heath MacNaughton of Edmonton was born on Oct. 16 with a faulty blood vessel leading from his heart. A DNA test pinned the cause on the newly discovered genetic mutation.

    The child's parents are relieved to know what caused the heart defect, but now they worry because his father passed on the mutation.

    "They'll be obviously following up if there's anymore children 'cause I guess there's a pretty good chance that our next child can have the problem as well," said Heath's mother, Leigh-Ann Cullinan.

    In Heath's case, the heart defect can be repaired with surgery, but other conditions will be more difficult to treat. Drugs could be used to enhance or turn down the signals coming from some genes, although the science is in its infancy.

    "We can't move toward therapy unless we can find the cause, so this is obviously the first step in that process," Somerville said.

    It's still early to know what the differences mean, Scherer acknowledged. "Though it does make you wonder, 'If you have one million fewer nucleotides than your buddy, shouldn't you get a break on your golf handicap?'"

  • #2
    Great Variability: is it all in the autosomal DNA ?

    The excerpt did not include this infirmation, but am I right in assuming that these variabilities and the specificity of effects, are confined to the Autosomal DNA, and do not refer to such as the Ydna identifiers? (Never mind mtDNA, which is really outside the genome for our purposes.)

    Comment


    • #3
      That's why we need higher resolution testing

      Originally posted by Dan Draghici
      We're more different than thought, genome map reveals

      Last Updated: Wednesday, November 22, 2006 | 1:50 PM ET

      CBC News

      A new genetic map written by an international research team has forced a fundamental rethink of how genes work and has already made a difference in diagnosing some genetic diseases.

      Stephen Scherer, a geneticist at the University of Toronto and the Hospital for Sick Children, and his colleagues found several hundred unusual mutations in a newly updated map of the human genome.

      The map was drawn up by analyzing DNA from 270 individuals from four populations with ancestry in Europe, Africa or Asia.

      "Now we know that our genomes are much more variable," said Scherer, whose study is in Thursday's issue of the journal Nature. "It changes the design of all of our studies. It really changes our understanding of ourselves in fact."

      The results of the study mean people are far more genetically variable than first thought. The new map shows genes don't always line up as expected — there can be mismatches, or chunks with missing or extra DNA.

      The mismatched genes and rogue chunks of DNA can cause profound and mysterious health problems that could explain some forms of autism, heart defects and Alzheimer's disease, researchers say.

      Genes usually occur in two copies, with one inherited from each parent. The researchers found about 2,900 genes, or more than 10 per cent of the human genome, had variations in the number of copies of specific DNA segments.
      Until now, research on genetic diseases has focused on small changes called single nucleotide polymorphisms, or SNPs.

      It may be that some diseases are instead caused by differences in the number of copies, and recent research suggests that's true for some types of kidney disease, Parkinson's disease, Alzheimer's and susceptibility to AIDS.

      Scherer's lab discovered a connection between pinched blood vessels and missing DNA.

      'Like a kink in a hose'

      Study co-author Martin Somerville, a professor of medical genetics at the University of Alberta, found six cases where a missing strand of DNA corresponds with an identical heart condition.

      "It's like a kink in a hose in a way of that main vessel," said Somerville.

      Heath MacNaughton of Edmonton was born on Oct. 16 with a faulty blood vessel leading from his heart. A DNA test pinned the cause on the newly discovered genetic mutation.

      The child's parents are relieved to know what caused the heart defect, but now they worry because his father passed on the mutation.

      "They'll be obviously following up if there's anymore children 'cause I guess there's a pretty good chance that our next child can have the problem as well," said Heath's mother, Leigh-Ann Cullinan.

      In Heath's case, the heart defect can be repaired with surgery, but other conditions will be more difficult to treat. Drugs could be used to enhance or turn down the signals coming from some genes, although the science is in its infancy.

      "We can't move toward therapy unless we can find the cause, so this is obviously the first step in that process," Somerville said.

      It's still early to know what the differences mean, Scherer acknowledged. "Though it does make you wonder, 'If you have one million fewer nucleotides than your buddy, shouldn't you get a break on your golf handicap?'"
      This is why we need higher resolution testing beyond the 67 marker test and autosomal tests. Costs can be prohibitive, but it would be nice to get more markers into panel tests.

      Comment


      • #4
        This is an enormous breakthrough. It's worth getting excited about. I suppose this is one of those things that will be appreciated more decades later--kind of like the introduction of the germ theory in medicine.

        One of the best reports of it can be read here: http://www.thestar.com/NASApp/cs/Con...2154&t=TS_Home

        I read one report that mentioned that DNA can now be used to trace the ethnicity of the people involved. Kind of intrusive if this info would be put into the wrong hands, isn't it?

        Comment


        • #5
          Originally posted by Arch Yeomans
          This is why we need higher resolution testing beyond the 67 marker test and autosomal tests. Costs can be prohibitive, but it would be nice to get more markers into panel tests.
          Can you refer us to a source that links CNVs with STRs and SNPs, from genealogical standpoint?
          Floyd Oakes
          Y-I1a
          mt-K1a

          Comment


          • #6
            Genomics; ethical challenges to come.

            [QUOTE=

            I read one report that mentioned that DNA can now be used to trace the ethnicity of the people involved. Kind of intrusive if this info would be put into the wrong hands, isn't it?[/QUOTE]

            Yes, there are people who discriminate against certain ethnicities other than (what they think) is their own.
            But wait until the insurance companies require autosomal results on which to base offerings of medical coverage!

            Comment


            • #7
              You're in good hands with...

              Originally posted by derinos

              Yes, there are people who discriminate against certain ethnicities other than (what they think) is their own.
              But wait until the insurance companies require autosomal results on which to base offerings of medical coverage!
              Wouldn't it be tempting to get an inexpensive test with fast results done, though?

              Comment


              • #8
                Yep we're exposed,but Honest Truthful ,knowledgeable

                [QUOTE=derinos]
                Originally posted by

                I read one report that mentioned that DNA can now be used to trace the ethnicity of the people involved. Kind of intrusive if this info would be put into the wrong hands, isn't it?[/QUOTE

                Yes, there are people who discriminate against certain ethnicities other than (what they think) is their own.
                But wait until the insurance companies require autosomal results on which to base offerings of medical coverage!
                That sounds kind of corny-anyone who gets DNA testing knows that their genes can be traced-that's exactly what customers paid for.We paid to expose our ass and in the process learn more about ourselves. If you don't get tested you could also be accused of being some ethnicity you aren't and be framed for that.But at least authorities can confirm who you are-it is as good as it is dangerous.When police swab felons to put in the criminal databases they know who they are.Police know what race/ethnicities all suspect felons are.So does the military who tests all soldiers.
                Last edited by Jambalaia32; 27 December 2006, 01:17 AM. Reason: add sentence

                Comment


                • #9
                  dNA FOR GOOD,I HOPE

                  [QUOTE=derinos]
                  Originally posted by

                  I read one report that mentioned that DNA can now be used to trace the ethnicity of the people involved. Kind of intrusive if this info would be put into the wrong hands, isn't it?[/QUOTE

                  Yes, there are people who discriminate against certain ethnicities other than (what they think) is their own.
                  But wait until the insurance companies require autosomal results on which to base offerings of medical coverage!
                  Anything can be used for evil-but I HOPE TO GOD THAT DNA IS USED TO help PEOPLE NOT TO HARM THEM.A PERSON DOESN'T HAVE TO KNOW YOUR DNA MAKEUP TO KILL OR TORTURE YOU NECESSARILY,ANYWAY.
                  Last edited by Jambalaia32; 27 December 2006, 01:22 AM. Reason: MISSPELL

                  Comment

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