Y chromosome DNA tests
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(Redirected from Y chromosome DNA test)A Y chromosome DNA test (Y-DNA test) is a genealogical DNA test which is used to explore a man's patrilineal or direct father's-line ancestry. The Y chromosome, like the patrilineal surname, passes down virtually unchanged from father to son. Every now and then occasional mistakes in the copying process occur, and these mutations can be used to estimate the time frame in which the two individuals share a most recent common ancestor or MRCA. If their test results are a perfect or nearly perfect match, they are related within a genealogical time frame. Each person can then look at the other's father-line information, typically the names of each patrilineal ancestor and his spouse, together with the dates and places of their marriage and of both spouses' births and deaths. The two matched persons may find a common ancestor or MRCA, as well as whatever information the other already has about their joint patriline or father's line prior to the MRCA. Y-DNA tests are typically co-ordinated in a surname DNA project. And each receives the other's contact information if the other chose to allow this.
Women who wish to determine their direct paternal DNA ancestry can ask their father, brother, paternal uncle, paternal grandfather, or a cousin who shares the same surname lineage (the same Y-DNA) to take a test for them.
Contents
What gets tested
Y-DNA testing involves looking at Y-STR segments of DNA on the Y chromosome. The STR segments which are examined are referred to as genetic markers and occur in what is considered non-coding DNA or "junk" DNA.
STR markers
A chromosome contains sequences of repeating nucleotides known as short tandem repeats (STRs). The number of repetitions varies from one person to another and a particular number of repetitions is known as an allele of the marker. An STR on the Y chromosome is designated by a DYS number (DNA Y-chromosome Segment number). The example below shows the allele of Skywalker's DYS393 marker is 12, also called the marker's "value". The value 12 means the DYS393 sequence of nucleotides is repeated 12 times—with a DNA sequence of (AGAT)12.
SNP markers
A single-nucleotide polymorphism (SNP) is a change to a single nucleotide in a DNA sequence. The relative mutation rate for an SNP is extremely low. This makes them ideal for marking the history of the human genetic tree. SNPs are named with a letter code and a number. The letter indicates the lab or research team that discovered the SNP. The number indicates the order in which it was discovered. For example M173 is the 173rd SNP documented by the Human Population Genetics Laboratory at Stanford University, which uses the letter M.
Understanding test results
Y-DNA tests generally examine 10-111 STR markers on the Y chromosome, but hundreds of markers are available. STR test results provide the personal haplotype. SNP results indicate the haplogroup.
Haplotype
A Y-DNA haplotype is the numbered results of a genealogical Y-DNA test. Each allele value has a distinctive frequency within a population. For example, at DYS455, the results will show 8, 9, 10, 11 or 12 repeats, with 11 being most common. For high marker tests the allele frequencies provide a signature for a surname lineage.
Kit | Surname | Haplo | 3 9 3 |
3 9 0 |
1 9 |
3 9 1 |
3 8 5 a |
3 8 5 b |
4 2 6 |
3 8 8 |
4 3 9 |
3 8 9 - 1 |
3 9 2 |
3 8 9 - 2 |
4 5 8 |
4 5 9 a |
4 5 9 b |
4 5 5 |
4 5 4 |
4 4 7 |
4 3 7 |
4 4 8 |
4 4 9 |
4 6 4 a |
4 6 4 b |
4 6 4 c |
4 6 4 d |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
11111 | Skywalker | Q | 12 | 23 | 13 | 10 | 16 | 17 | 12 | 12 | 13 | 14 | 14 | 31 | 18 | 8 | 9 | 11 | 11 | 27 | 13 | 19 | 28 | 14 | 14 | 15 | 15 |
The test results are then compared to another project member's results to determine the time frame in which the two people shared a most recent common ancestor (MRCA). If the two tests match perfectly on 37 markers, there is a 50% probability that the MRCA was fewer than 2 to 3 generations ago, a 90% probability that the MRCA was fewer than 5 generations ago, and a 95% probability that the MRCA was fewer than 7 generations ago.
Kit | Surname | Haplo | 3 9 3 |
3 9 0 |
1 9 |
3 9 1 |
3 8 5 a |
3 8 5 b |
4 2 6 |
3 8 8 |
4 3 9 |
3 8 9 - 1 |
3 9 2 |
3 8 9 - 2 |
4 5 8 |
4 5 9 a |
4 5 9 b |
4 5 5 |
4 5 4 |
4 4 7 |
4 3 7 |
4 4 8 |
4 4 9 |
4 6 4 a |
4 6 4 b |
4 6 4 c |
4 6 4 d |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
11111 | Skywalker | Q | 12 | 23 | 13 | 10 | 16 | 17 | 12 | 12 | 13 | 14 | 14 | 31 | 18 | 8 | 9 | 11 | 11 | 27 | 13 | 19 | 28 | 14 | 14 | 15 | 15 |
11178 | Skywalker | Q | 12 | 23 | 13 | 10 | 16 | 17 | 12 | 12 | 13 | 14 | 14 | 31 | 18 | 8 | 9 | 11 | 11 | 27 | 13 | 19 | 28 | 14 | 14 | 15 | 15 |
STRs results may also indicate a probable haplogroup, though this can only be confirmed by specifically testing for that haplogroup's single-nucleotide polymorphisms (SNPs).
Articles
- Why the Big Y-700
- Exploring the Y Part 1 by Kelly Wheaton. Wheaton Surname Resources website.
- Exploring the Y Part 2 by Kelly Wheaton. Wheaton Surname Resources website.
- More with the Y by Kelly Wheaton. Wheaton Surname Resources website.
- The future of Y-DNA testing is here by Kelly Wheaton. Wheaton Surname Resources website.
- Y-DNA testing for genealogy by Rebekah Canada, Haplogroup blog
- What will a Y-DNA test tell you? by Debbie Kennett, Who Do You Think You Are? Magazine, 2019.
- Demystifying DNA 2: Y-DNA tests by Karen Cummings. Genealogical Ponderings 1 July 2018.
- Using Y-DNA for genealogy by Debbie Parker Wayne. US National Genealogical Society NGS Magazine 40 (January-March 2014): 20-24.
- Should I upgrade my Y-DNA test to 67 or 111 markers by Maurice Gleeson, DNA and Family Tree Research blog, 21 June 2016.
- Getting the most out of your Y-DNA test by Maurice Gleeson, DNA and Family Tree Research blog, 1 April 2016.
- DNA 101: Y chromosome testing by John Blair, Blair Genealogy website, 12 July 2010 (last updated on 17 January 2013).
- Understanding Y-DNA genealogical DNA testing by Steve Handy, DNA Genealogical Experiences and Tutorials blog, 3 November 2012.
- DNA testing for genealogy - Getting started, Part One: Y-DNA testing by CeCe Moore, Geni.com blog post, 18 July 2012.
- Understanding your Y-DNA matches at Family Tree DNA. World Families tutorial, 28 May 2012.
- Is the answer in your genes? by Debbie Kennett, an expanded version of an article first published in the Berkshire Family Historian, September 2008 (Volume 33), pp14-16.
- Whose Y to use? Paternal ancestry for ladies 23andMe blog, 7 May 2008.
- Why Y? The Y chromosome in the study of human evolution, migration and prehistory by Neil Bradman and Mark Thomas. Science Spectra 1998, Number 14.
- Signature marker values - what they are and how to use them by Diana Gale Matthiesen
- The role of inbetweeners in the analysis of Y-DNA test results by Diana Gale Matthiesen
FTDNA resources
- DNA test basics: paternal lineages
- Y-DNA testing - it's not just for men by Katy R, FamilyTreeDNA blog, 23 December 2019.
- My FTDNA user guide: Y-DNA results pages
- Advanced DNA: Y-DNA STR testing
- FTDNA TiP
- Advanced DNA: Y-DNA SNP testing and haplogroups
Y-DNA resources
- Y-chromosome DNA A video from the Sorenson Molecular Genealogy Foundation now hosted on the Learn Genetics website
- Y-DNA inheritance chart Created by Dennis West, to illustrate the path of the Y-chromosome
Examples
Specific examples of the application of Y-DNA testing using the case of Thomas Jefferson and results from the the Spearin Surname Project can be seen in this video presentation by Maurice Gleeson:
See also
- Before You Buy
- Free DNA tests
- Generation length
- Match
- SNP testing
- Success stories
- Y-DNA SNP testing chart
- Y-DNA STR testing chart
- Y-DNA haplogroup projects
- Y-DNA tools
- Y-STR
Licence
This article is licensed under the GNU Free Documentation Licence. It incorporates material from the Wikipedia article "Genealogical DNA test".