Demystifying DNA Results

Demystifying DNA Results

What happens after you order a DNA test? What does that pile of numbers mean? Our layperson's guide addresses privacy concerns and tells how to analyze your results report.

Testing anxiety
Happily, DNA testing no longer involves bloodletting. You’ll order a test and get a cheek-swab kit—a toothbrush-like device you use to painlessly scrape the inside of your cheek—in the mail. You ship your cells to the testing company, which codes the sample to protect your identity and sends it to a university lab for testing.

With “Big Brother” privacy concerns getting so much attention these days, DNA testing may seem risky. What if the wrong people get their hands on your results—could they find out whether you’re a health time bomb waiting to explode? Learn your true parentage? Keep your sample and use it again without telling you? It’s highly unlikely: The testing that’s done for genealogical purposes differs from medical, paternity or criminal testing. In fact, if police were to use Y-DNA testing to solve a crime, they’d have to haul in hundreds or thousands of distant cousins as suspects.

Testing companies promise to keep your identity and test results secure. If you choose to have your results posted in an online database, you’ll be identified by code rather than by name. The Web site can serve as an intermediary should a match want to contact you—or you can withhold your contact information. Surname-project managers who receive results for their group generally post results on the Web using a code or, as is rapidly becoming the standard, the name of the earliest known ancestor. If you’re concerned, you can deny the testing company or project manager permission to share your data in any way.

Ask your testing company what happens to samples after they’re tested. Some companies destroy them; others keep them (unless you direct otherwise) in secure storage in case a client wants additional, more-precise tests. Since the lab knows you’re interested in genetic genealogy, you may be asked to participate in research studies, but no reputable lab will test your sample without your permission.

Getting results
You’ll probably wait two to six weeks to receive your results in the mail or online, if you used a company that lets you view your results on its Web site using an access code. They’ll consist of a chart with what resembles a pile of numbers. If you took the popular Y-DNA test, they represent the numbers of STRs for each marker your test evaluated. How do you interpret them? You’ll want to perform three levels of analysis:

1. Within your surname project: If you’ve joined a DNA surname project, your first step is to compare your results with others in your project. A person with a perfectly matching haplotype will show the same number of STRs for each marker as you; a near match will show differences (or mutations) on perhaps one to three markers—the rarer your haplotype, the more mutations you’re willing to tolerate in a match. It’s definitely worth collaborating on genealogical research with matches and near matches. Your family trees likely overlap at some point, so share details about your earliest known ancestor and where he resided—even if your MRCA predates a paper trail. Maybe you know your ancestor hails from Ireland, and a few of your matches have traced their lines to County Armagh. Now you know where to focus.

If you’re a genetic orphan in your study—with no haplotype matches in sight—you’ll just have to wait. As the project grows, someone should eventually match you. If you have no matches in a sizeable project, it’s probably time to inspect your research for errors and hints of illegitimacy, adoptions or other nonpaternity events.

2. Through your testing company: Whether or not you have any matches within your study, look at the information your testing company supplies. For instance, most companies provide a list of customers outside your project who share your haplotype or come close (and have given the company permission to share their information). If you have a common haplotype that’s shared by 50 others, you probably won’t want to launch an e-mail campaign — but if you match only one or two others, it doesn’t hurt to contact them.

Your testing company may provide other information, such as an ethnic analysis that lists the self-declared nationalities or ethnicities of your close matches. A customized analysis might blend and interpret your genealogical and genetic data, even indicating when a mutation might have occurred or where your research may have a glitch.

3. In online genetic-genealogy databases: Once you’ve exhausted the resources of your surname project and testing company, investigate online databases for more matches. The following four databases operate more or less the same way: Use a drop-down menu for each marker to enter your results, then compare them to others. The sites contain some overlapping data, but each one also has unique content and a spiffy feature or two that makes it worth checking out.

? Scientists designed the Y Chromosome Haplotype Reference Database (YHRD) <www.yhrd.org> for other scientists, but genealogists discovered it back when they had no other options. You can’t upload your data, but you can search. With more than 26,000 haplotypes representing 229 populations, YHRD doesn’t provide names, but tells you where your haplotype mates are.

? The first public database created specifically for genealogists, Ybase <www.ybase.org> is affiliated with the company DNA Heritage. You can enter your results and search for matches among more than 2,800 haplotypes and 4,400 surnames. Extra features include allele statistics, which can help you understand how common or rare your results are for any one marker, and surname distribution maps.

? Family Tree DNA’s Ysearch <www.ysearch.org> lets you link your genetic and genealogical data by uploading your test results and GEDCOM file. You can easily search more than 6,300 haplotypes and 8,100 surnames, and use built-in tools (Y Search Compare and Genetic Distance) to take a closer look at individuals of interest to you. In late 2004, the company launched an mtDNA database called Mitosearch <www.mitosearch.org>, which contained 500 individuals’ results at press time. You can enter results from any testing company, search for matches and compare two people.

? The Sorenson Molecular Genealogy Foundation(SMGF) database <www.smgf.org> was the first to combine genetic and genealogical data. Although you can’t upload your own results, they eventually will find their way into this database if you participate in the SMGF genetic genealogy project. In the meantime, you can search 9,800 plus haplotypes representing more than 6,600 surnames, and explore the pre-1900 family trees for matches.

Who knows? Maybe you’ll find a cousin. Only you can decide whether DNA testing is a good next step, but for a growing number of genealogists, the answer is a definite yes. If you’re dealing with stubborn brick walls, wishing for a way to verify your traditional research, or struggling with your Smith or Jones line, it might be time for you to take the test.
 
From the February 2005 Family Tree Magazine

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