Senior Project Presentation[1]


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I investigated the assumption that race and ancestry can be determined using DNA sequence analysis. I was able to present the results of my senior project at Luther College Research Symposium in April 2010.

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  • A genetic marker is a DNA sequence with a known location on a chromosome. A genetic marker can be used to track inheritance since some of them encode for visible characteristics such as blood types.
  • Restriction enzymes recognize very specific sequences of nucleotides in DNA (including mtDNA). So, mtDNA from different individuals rarely have the exact same array of restriction sites and distances between these sites. Therefore, a population is said to be polymorphic (many forms) for these restriction fragment patterns. These differences are referred to as RFLPs.
  • SNPs are small variation that can occur within a person’s DNA. For instance, instead of AAGCT sequence in a SNP there will be an alteration of the second A to T to give ATGCT. Due to their high frequency in the genome and their relative genetic stability; SNPS are excellent biological markers.
  • Senior Project Presentation[1]

    1. 1. Investigation of Ancestry Testing by DNA Sequence Analysis<br />Debora Mukaz<br />
    2. 2.
    3. 3. BACKGROUND<br />Series of documentary by Henry Louis Gates, African American Lives and II, which tried to identify the ancestral and racial background of African American celebrities:<br />The first-entry of the series hit close to home when they tested the famous neurosurgeon, Ben Carson, and found out his ancestors were from my ethnicity (Lunda). <br />Discussion with Professor Kaehler, who then told me that racial and ancestral concepts in genetics were not as simple as the document was trying to portray them<br />Desire to learn more about the DNA testing companies<br />
    4. 4. HISTORICAL DEVELOPMENT OF THE CONCEPT OF ANCESTRY AND RACE<br />Herodotus(fifth century, B.C): father of Greek history, he studied different populations mostly around the Mediterranean<br />Carl von Linnaeus(1707-1778): Swedish scientist who classified humans into separate categories using the binomial system<br />Anders Retzius(1796-1860): another Swedish scientist who introduced a system of classification of human ‘races’ using the cranio-metric criteria<br />Charles Darwin( 1809-1882): argued against full infertility in humans and concluded that there was one human species<br />The major advance in the study of human ancestry has been the introduction of genetic markers after World War II<br />
    5. 5. Information in DNA<br />
    6. 6. Information in DNA<br />DNA transmits the information in its sequence of four types of bases, which are adenine (A), thymine (T), guanine (G) and cytosine (C).<br />To study ancestry two types of DNA are used: Mitochondrial DNA and Y-Chromosome DNA<br />Y-chromosome DNA is transmitted from father to son<br />mitochondrial DNA or mtDNA is exclusively inherited from the mother.<br />For the purpose of this study, only mtDNA was used since we wanted to have both male and female subjects .<br />
    7. 7. Mitochondrial DNA or mtDNA<br />mtDNA is found in the mitochondrion, which is a cytoplasmic organelle with its own membrane <br />mtDNA genes are exclusively transmitted by the mother<br />The only region of the mtDNA that has significant variability is the D-loop, or control region, whichis highly variable and rapidly evolving relative to the rest of the mitochondrial genome.<br />The control region is divided into 2 distinct regions known as hypervariable 1 ( HV1 or HVR1) and hypervariable 2 (HV2 or HVR2) . <br />mtDNA relative small size and the fact that it has unrepaired and faster mutations make it a good target to identify differences among individuals and populations<br />
    8. 8. mtDNA analysis to study ancestry<br />By coupling mtDNA sequence analysis and RFLS analysis, a fairly refined human phylogenetic tree has been produced, with branches for different geographic regions of the world. <br />the ability of restriction analysis to trace human genetic history based on the observation of Restriction Fragment Length Polymorphisms (RFLPs) <br />mtDNA sequencing: Frederick Sanger’s method and mirofluidics environment<br />
    9. 9. Experiment<br />5 consenting subjects were selected based on their historical sense and their geographic ancestry <br />The subjects’ mtDNA samples ( obtained from cheek swabs) were sent to 4 different companies: The Genographic Project, DNA Family builder, DNA Heritage and Family Tree DNA<br />the tests, the mtDNA regions used by the companies and the results obtained.<br />Advantages and disadvantages of using mtDNA testing to find out about ancestry were assessed<br />
    10. 10. Comparisons of tests and used mtDNA regions<br />Each company tested specific sites of the mtDNA control region. <br />Tested regions were either identical among companies or overlapped<br />Family Tree DNA is the only one to have tested a backbone of 20 SNPS<br />
    11. 11. Comparison of results: haplogroups<br />To keep the names of the subjects anonymous: AA, BB,CC, DD and EE were used in place of their real names<br />For all the 4 companies, AA belonged to Haplogroup L subclade L1<br />For all the 4 companies CC belonged to haplogroup H<br />As for DD, all of the companies show him belonging to haplogroup A <br />For 3 of the 4 companies (Family Tree DNA, DNA Heritage and The Genographic Project), BB belonged to Haplogroup T while DNA family builder identified BB with haplogroup H. <br />As for EE, 3 out of 4 companies (The Genographic Project, DNA Heritage, Family Tree DNA) identified the subject as belonging to haplogroup H while the fourth one, DNA family builder identified EE with haplogroup T. <br />Some of the companies such as DNA Heritage, were very specific since they gave the subclade and subgroup of subjects’ haplogroups<br />
    12. 12.
    13. 13. Comparison of results: migration patterns of haplogroups<br />Haplogroups T and A covered such broad swaths. Both haplogroups T and A included the most part of Europe and Asia<br />As for haplogroups L and A, they are more mostly well defined within the borders of certain continents. L is an African haplogroup while A is mostly found in East Asia and is present with some populations in the Americas.<br />
    14. 14. Debora Mukaz’s results<br />The format and content of information a subject received from each of the 4 companies was quite variable. Some limited descriptions of human migration were present but often times they were very vague.<br />For all the 4 companies, I belonged to Haplogroup L subclade L1. L1 is mostly found in Central Africa<br />
    15. 15. Advantages of using mtDNA testing to find out about ancestry<br />Help people get a better understanding of their different haplogroups<br />Reconnect individuals with their ancestral history<br />
    16. 16. Disadvantages using mtDNA testing to find out about ancestry<br />All the results were given as haplogroups and migratory maps, which often times, did not give specific and clear information about the subjects’ backgrounds<br />Can mislead people especially those who have no basic knowledge of genomics<br />Companies were not specific so people might be disappointing for people who expected more<br />Some of the companies go as far as to say they can predict race. Yet, race is a social construction<br />