SEARCHES FAMILY TREES MAILING LISTS MESSAGE BOARDS

3.  Technical Information on Y-chromosome testing

Other pages accessed via this portal
1. Portal entrance
2. List of Y-Chromosome DNA studies underway by family historians
4. Background to the science of genetics and modern applications of it
  
5. History since the last Ice Age: national and international DNA projects
6. Using DNA to unravel man's ancient origins

Sections on this page
3.1.  Issues for Family Historians organising DNA Testing Progammes
3.2.  Caveats relating to the statistical analysis of DNA results
  
3.3.  Key Academic Researchers


3.1.  Issues for Family Historians organising DNA Testing Progammes

I'm not an expert on DNA science, and I doubt whether in a few years' time family historians will need to be. We can expect that over the next few years it is likely that the test itself will become standardised (re the number of markers used and their selection) and that its price will fall to that of a commodity rather than as a luxury. At the moment the two major issues for organisers concern the selection of a lab (the markers used in the test and benefits for groups of testees) and the privacy issues surrounding the use of DNA samples.

If you read the background materials on cited here you'll have a good grounding in the issues and practices, and if you want more then the Genealogy-DNA mailing list archives are a good place to check what the current concerns are and how people feel about them. Kevin Duerinck's website is a good single place to check for relevant background information. As an example, check out his notes about polymorphic changes (mutations) in the Y-chromosome, particularly the section on the four main types of mutations -- snips, indels, microsatellites & minisatellites -- that constitute each man's haplotype which is well worth reading.

Organising your study

Several people who've already organised test series have created thoughtful descriptions of the process. The most comprehensive are by Ron Lindsay and Kevin Duerink. Sanford Toole's site has a sign-up form that can make the process even easier to manage while Kevin Duerinck's has a sample waiver form.

DNA markers & selecting a lab

Would-be study organisers need to consider which lab they want to work with when setting up a programme of tests. No standard minimum test for family history purposes has yet been agreed and different labs use different markers of the Y-chromosome in their testing processes. The current number of markers used in tests offered to family historians ranges between 10-23, It is doubtful whether, using current technology, the number of markers will increase significantly. There are some problems reported with calibrating results between labs for the same markers, though each lab provides consistent results within each test series. For a full list of potential markers review the NIST database and files on each marker.

Finding a match: databases of DNA halotypes

Once you have results you'll need to check several external haplotype databases. There are three that cover the geographical areas of North America, Europe and Asia run by Drs Lutz Roewer and Sascha Willuweit of the Institute of Legal Medicine, Humboldt University, Berlin. These are in their infancy but the numbers of results they contain are growing over time. Some testing companies offer to link testees to other people who've tested with them that have the same haplotype, but this be of only limited usefulness until many, many more men have tested.

Software to present Y-chromosome results

The only dedicated software I am aware of is some Windows/DOS s/w for creating phyllogenetic network charts produced by a German firm called Fluxus Engineering. My advice is not to attempt to install it unless you positively enjoy installing software on your PC as some people have reported that it turned out to be a bit too complex for them to handle.

TABLE: Databases DNA testing companies Studies
(Please read notes at foot of table for details of Group rates)
 Y-STR databases Oxford Ancestors FamilyTree DNA Relative Genetics & Ancestry GeneTree Pomeroy study
No. of markers: 10 10 25 22 22 14
For Individuals   US$ 220 US$ 209 - US$ 225  
For Groups   US$ 190 US$ 149 US$ 195 -  
DYS 19 = 394 * * * * * *
DYS 288
DYS 289
DYS 310
DYS 384
DYS 385a * * * *
DYS 385b * * * *
DYS 388 * * * * *
DYS 389i * * * * * *
DYS 389ii * * * * * *
DYS 390 * * * * * *
DYS 391 * * * * * *
DYS 392 * * * * * *
DYS 393 * * * * * *
DYS 395
DYS 425 * *
DYS 426 * * * * *
DYS 434
DYS 435
DYS 436
DYS 437 * * *
DYS 438 * *
DYS 439 = Y-GATA-A4 * * *
DYS 447 *
DYS 448 *
DYS 449 *
DYS 454 *
DYS 455 *
DYS 458 *
DYS 459a *
DYS 459b *
DYS 460 = Y-GATA-A7.1 * *
DYS 461 = Y-GATA-A7.2 * *
DYS 462 * *
DYS 464a *
DYS 464b *
DYS 464c *
DYS 464d *
YCAII * * *
GGAAT1B07 * *
Y-GATA-A8
Y-GATA-A10 * *
Y-GATA-C4 * *
Y-GATA-H4 * *
M9 *
92R7 *
SRY 1532 *
YAP = DYS 287 *

Notes to the table above:



There is also a MtDNA database viewable at the Emory University website.

Return to top of page


3.2.  Caveats relating to the statistical analysis of DNA results

The current rule of thumb for 'false paternity', the generic term used to cover all of the different reasons for the break in direct father-to-son DNA transmission, is 2-5% per generation (or once in every 20-50 generations). We also don't know whether the likelihood of illegitimacy, which one can expect would be the main transmission method for new DNA into a surname, is a constant over the centuries or between different communities. There is currently a huge debate over this one topic. The accepted average rate of naturally occurring Y-chromosome mutation is around 0.2% per generation, or once in every 500 generations (around 10,000 years).

These averages do, however, mask several potential problems for family historians running DNA test programmes. Although one haplotype may be found in more testees than another, this doesn't prove it is the haplotype of the common ancestor of the surname as a whole (the modal haplotype). Even if the test organiser knows exactly how all the men being tested are related to each other, which one generally does not, the largest group of living descendents is not necessarily the oldest group. It is conceivable that the *genuine* oldest ancestor has only a very few modern-day descendents. The statistics involved in processing all the variables derived during the tests is pretty fearsome.

Many DNA test sets consist of very small numbers of men. Even a relatively large group like the 51 put together for the Pomeroy project doesn't escape this problem. The randomness are the samples, and if they are not random how many assumptions have been built into their selection, has a major influence on the statistical robustness of the results. One needs a large sample to help minimise the distorting effect of non-paternity events introducing new DNA to a surname.

Finally, many of the assumptions being used in calculations have yet to be nailed down to a small variation in value. For example, Y-chromosome tests generally measure at least 8-12 microsatellite loci each one of which has its own, often as yet unknown, mutation rate. The 0.2% rate of naturally-occuring mutation mentioned above is an average of these averaged estimates. Testing more microsatellites might help, but again not enough tests have been done yet to create locus-specific mutations rates. A recent study using known genealogies or "deep-rooting pedigrees" by Mark Jobling puts the rate at 1:257 transmissions, but in a sense this is a circular argument and more studies need to be done per loci to clarify these variables. The most detailed paper on the topic is by Kayser et al Characteristics and Frequency of Germline Mutations at Microsatellite Loci from the Human Y Chromosome, as Revealed by Direct Observation in Father/Son Pairs published in The American Society of Human Genetics in February 2000.

It is possible that different microsatellite loci other than the ones generally used at the moment (which are used because they are relatively easy to test) would yield more accurate results. Genetic studies are so new that the nomenclature has in many cases yet to be fixed.
Return to top of page


3.3.  Key Academic Researchers & Commercial Labs


A range of academics have links with commercial labs. In the UK the key academic researchers in the field are: In the USA, the most visible academic research is by: There is a site focused on African ancestry linked to Howard University in Washington D.C., but nothing appears to have changed on it during 2001. Another site named simply The Seeker appears to claim to be aiming to build up a global universal DNA database wide enough to help adoptees find their birth parents. A German site appears to be under construction.


GO NEXT TO:   4. Background to the science of genetics and modern applications of it


All corrections & updates should be sent to the page maintainer: Chris Pomery
Last updated: 28th November 2002. Page launched: 8th July 2001.




Census Records | Vital Records | Family Trees & Communities | Immigration Records | Military Records
 Directories & Member Lists | Family & Local Histories | Newspapers & Periodicals | Court, Land & Probate | Finding Aids