Wendy Wilson Spooner ~ Genetic Genealogist, Lic. G., LCoT
- Wendy Wilson Spooner
(Article adapted from paper written by Wendy Wilson Spooner May 2014, for the American School of Genealogy, Heraldry, and Documentary Sciences, a subsidiary of the International College of Interdisciplinary Sciences)
Every part of the human body is comprised of cells containing a set of DNA identical to that of every other cell in the body. Most cells contain DNA including brain, muscle, blood, sperm, liver, and many other types of cells. Few exceptions exist, one being red blood cells, although blood itself can be typed through the DNA contained in white blood cells (Riley, 2014).
Prior to testing, individuals will find advantage from understanding the testing procedure, the limitations and benefits of testing, as well as the possible out-comes of test results. Genetic tests are performed on samples of saliva, hair, skin, blood, amniotic fluid, or other tissue. For example, a method called a buccal smear uses a small brush or cotton swab to collect cell samples from the cheek surface inside the mouth (How Is Genetic Testing Done? 2014).
Once a person’s DNA sample arrives at a lab, the procedure for processing and testing may be rather similar to that of the company 23andMe. Hundreds of samples arrive at the company’s CLIA-certified lab every day. To ensure sample quality (such as enough saliva deposited in the customary sample tube), a lab technician carefully inspects each vial. Since 0.5% of saliva is comprised of cells, the cell material is a prime source for DNA testing. The sample at this point is entered into the lab inventory system and DNA is extracted from the cells. Copies (amplification) are made of the DNA to generate enough material for analysis. 23andMe uses a DNA genotyping chip, which is custom designed to capture key features about health and ancestry. The DNA is placed on this chip and the temperature is increased for incubation. This process encourages the DNA to attach to the chip for hybridization, of which a computer then reads the information. Throughout the testing process, customers can track sample status on the 23andMe website. Once the data is processed completely, a notification email is sent to the testee for result viewing (23andMe Processing Lab, 2014).
Additional information important to know before testing, is that a full set of genetic code is called a genome. Human beings have two genomes, the nuclear genome, and the mitochondrial genome (What Is the Mitochondrial Genome and Why Compare These Sequences? 2014). Composed of 46 chromosomes (23 pairs), the human nuclear genome contains 3 billion base pairs. Composed of a single circular DNA sequence, the human mitochondrial genome contains 16569 base pairs (Canada, 2014).
DNA testing for the use of genealogy can involve multiple types of tests. For example, a Y-chromosome test (found in nuclear DNA), is a male-only test, and will assist with research in the paternal or surname line. Females can have a close male relative test to discover similar results. When analysis takes place for Y-DNA, lab technicians view multiple small sections or ‘markers’ (Hart, 2002) in which Short Tandem Repeats (STRs) are produced. The code on these sections will repeat, for example, 15 times. If a marker is named DYS19, the result will be labeled DYS19=15 (Hart, 92).
These STRs are counted at each marker and reported as an individual’s DNA test results. Analysis of several of these markers provides a ‘haplotype.’ The repeat profile inherited from father to son is the differentiation of one specific paternal lineage, from another. Accordingly, the next step is to compare haplotypes to find relationships. If DNA mutations did not occur, every male person would have identical Y-chromosomes. Mutations (small errors formed when the DNA is copied) are helpful for analysis because they occur at a fairly fixed frequency over time. When mismatches occur during two male haplotype comparisons, the conclusion is ‘not related.’ When a match is evident, a common surname or shared haplotype of two individuals, raises the probability of a relationship significantly (Hart, 17).
In addition to a Y-chromosome test, another helpful family history DNA test is the mtDNA (mitochondrial) test. This test is useful in finding genetic relationships along a direct maternal line. Once again during testing, mutations (or polymorphism) differences are compared to the DNA result differences (Canada, 2014).
Leading DNA Testing Companies for Genealogical Use
The leading DNA companies which test specifically for family history use include: Family Tree DNA, AncestryDNA, and 23andMe. Family Tree DNA is based in Houston, Texas and is a division of Gene by Gene, a commercial genetic testing company. Founded in 1999 by Bennett Greenspan, Max Blankfeld, and Jim Warren, this company offers international services of mtDNA, Y-STR, Y-SNP, and Autosomal DNA testing. This company’s main focus is genetic genealogy (Family Tree DNA, ISOGG, 2014).
AncestryDNA is the genetic genealogy database service of Ancestry.com. Although the company does not carry out the actual testing (testing is contracted out by Sorenson Genomics), they offer an autosomal test, and a basic mitochondrial test. The company offers testing result comparisons, reviews, surname searches, and transfer of test results from other companies (Ancestry DNA, ISOGG, 2014).
23andMe is a privately held biotechnology and Personal Genomics company based in Mountain View California. Founded in 2006 by Anne Wojcicki and Linda Avey, the company offers DNA test kits, genetic testing, and an online genome service, as well as adoption, deep ancestry, ethnicity, genealogy, and health information testing results. The company is sponsored by investors such as the National Education Association, Google, and MPM Medical Inc. (23 and Me, ISSOG, 2014).
A closer look at the services provided by FamilyTreeDNA begins with the Advanced Matching page. This tool allows individuals to compare genetic matching with multiple types of DNA tests including Family Finder, mtDNA, and Y-DNA. Filtering options may be selected to custom view matches in the Results section. Filter options consist of: test types, which types of matches to display, surname sorting, and ‘number of results to display per page’. Match Results displays links to match’s email addresses, profiles, family trees, and notes. As well, users can view the relationship range of matches, and matches according to the particular DNA test results submitted (Canada, 2014).
Additionally, Family Tree DNA’s Known Relationship Page is the page to manage known relationships with Family Finder matches. Those relatives that have been confirmed with traditional genealogical records on one’s family tree, are the known relationships. Three user-friendly tab labels show the known relationship statuses, which are: Your Known Relationships (fully confirmed relationships), Pending Relationships (relationships an individual’s matches have suggested), and Sent Requests (relationships users have suggested to their matches) (Canada, 2014).
23andMe has developed some new and exciting methods to determine relationships with other DNA testers. The company has recently improved their methods for finding relatives, by utilizing a time-tested method. This method detects shared DNA segments used by researchers to analyze whether or not two individuals are related, and demography and the heritability of disease. Biologists Eric Durand, PhD, and Cory McLean, PhD, recently made their findings available to the public on their algorithm called HaploScore. Their findings were published in the Molecular Biology and Evolution journal stating that Durand and McLean are the first to test established methods for determining identity-by-descent (IBD) with real human data. HaploScore will generate improved ancestry reports within 23andMe and allow researchers to more accurately determine genetic relationships between distantly-related people (23 and Me Blog, 2014).
Ancestry.com’s enormous subscriber base implies that the AncestryDNA database is growing at an astounding rate. Subscribers can link DNA test results to their own Ancestry.com-hosted family trees. To discover common ancestors, Ancestry.com’s services compare any genetic relatives of an individual to those in their trees. A Genetic Ethnicity Summary is also offered by AncestryDNA in which comparisons are made with a person’s DNA results, to the results of populations all over the world (Bettinger, 2013).
Along with a testing company’s analysis, those with DNA test results can use third-party software and websites to search for matches and gain a better understanding of result data. DNA Tools by Family Tree DNA can be used by customers to download Family Finder matches, and store DNA segment data shared with those matches. 23andMe customers can also download specific data and test results concerning genetic cousins (Bettinger, Para. 9).
GEDmatch is a free service in which raw autosomal DNA results may be uploaded in search of genetic cousins. As well, users can utilize admixture calculators to examine ancient ethnicity in thorough detail, and compare results with those in the GEDmatch database. GEDmatch can also be used to compare a match’s results with one’s GEDCOM, to assist in the identification of shared ancestors. Additionally, GEDmatch’s Phasing Tool allows users to ascertain which DNA came from individual grandparents, great-grandparents and beyond (Bettinger, Para. 10).
Three more analysis tools (free to the public) include Interpretome, Promethease, and Y-Chromosome Genome Comparison. Interpretome is a free Stanford University browser-based tool, which analyzes 23andM3 raw data, including genetic predisposition for health conditions such as diabetes. Promethease is free software which tests results from Family Tree DNA, 23andM3, and other testing companies. Promethease provides reports for additional health and trait information. The service also uses SNPedia, a growing database of information concerning links between genetics, physical traits, and disease. Y-Chromosome Genome Comparison is a free collaborative tool created to learn more about the Y-DNA family tree. Genetic genealogists use this publicly available information to further refine the Y-DNA global haplogroup tree. Additionally, MitoSearch.org, 23andYou, and ISOGG (International Society of Genetic Genealogy) are further resources for DNA testing, genealogy, and education purposes (Bettinger, Para. 11-14).
DNA Test Results: Important Data to Add to Genealogical Files
Combining one’s own (or another’s) DNA test results with genealogical research, is a learning process. The procedure may begin with molecular prosopography, an independent science involving the social history of genealogy, onomastics, and demography. Because genes have both a biological and cultural component, onomastics (a cultural component), is useful as the study of the origin of a name, and the related historical and geographical application. Demography is useful as the study of the development of social characteristics of a population (Hart, 23) and Phenomics is useful as the science used “to customize and individualize medicines and other health treatments, to the total human genome of one person.” (Hart, 24).
According to Anne Hart, future generations will need a DNA history of any and all ancestors willing to participate. Family historians need a bridge to fill the gap between genetics and genealogy – the information based on oral histories and records. Genealogists and family historians have not only a family history to archive, but now a genome, or at least a matrilineal and patrilineal record of ancestry by DNA (Hart, 24-25).
Valuable DNA tests can be added to a family database and file records, and then passed on to family members for the use of future generations. As well, the genome can be shared with health care professionals to customize therapy or treatment, and tailor nutrition. The genealogist can now piece together records of diaries, and women’s clubs, etc., by adding DNA test data for revealing details of one’s maternal lineage. Also, combining military pension, service records, village society and Census records, with Y-chromosome test results, offers a better look at paternal lines (Hart, 31) When DNA is added to family history records, files, and artifacts, the descendants of a family will have a much better idea of a family’s identities instead of merely studying anonymous photos (Hart, 33).
23andMe Blog. May 12, 2014. Accessed May 29, 2014. http://blog.23andme.com/23andme-research/23andme-scientists-improve-methods-for-finding-relatives/?utm_source=rss&utm_medium=rss&utm_campaign=23andme-scientists-improve-methods-for-finding-relatives.
“23andme DNA Processing Lab” (video). 2013. Accessed May 27, 2014.https://www.23andme.com/you/.
AncestryDNA. Accessed May 27, 2014.http://ldna.ancestry.com/learnMorePaternal.aspx.
Bettinger, Blaine. “Top Genetic Genealogy Tools: Ancestry.com.” Family Tree Magazine, June 24, 2013. Accessed May 29, 2014. http://www.familytreemagazine.com/article/top-genetic-genealogy-tools.
Canada, R. A., FamilyTreeDNA. Accessed May 29, 2014.https://www.familytreedna.com/learn/dna-basics/mtdna/.
Hart, Anne. How to Interpret Your DNA Test Results for Family History. New York Lincoln Shanghai: Writers Club Press, 2002.International Society of Genetic Genealogy. January 1, 2014. Accessed May 29, 2014.http://www.isogg.org/wiki/23andMe.
Naturalis Historia. “What Is the Mitochondrial Genome and Why Compare These Sequences?” Accessed May 29, 2014. http://thenaturalhistorian.com/2013/02/26/kinds-baramins-creationism-mtdna-genomes-compared/.
Riley, Donald E. “DNA Testing: An Introduction for Non-Scientists an Illustrated Explanation.” Scientific Testimony (April 6, 2005): 1. Accessed May 27, 2014.http://www.scientific.org/tutorials/articles/riley/riley.html.U.S.
National Library of Medicine. “How Is Genetic Testing Done?” Accessed May 27, 2014.http://ghr.nlm.nih.gov/handbook/testing/procedure.