DNA Matching

Our Clan has an active project to help you understand your ancestors going back well beyond what can be achieved with genealogy. The original advisor to the project was Dr David H MacLennan OC, a medical researcher and retired professor. A a set of “Questions and Answers” between David and Melanie MacLennan about DNA testing can be found from the links below. David’s most distant known ancestor, George McLennan – i1121 in the Clan database – was born in Redcastle in Killearnan parish in 1776. His son, George McLennan 1810-1883, migrated to Canada in 1842.

The Y-Chromosome is carried only by men who inherit it from their fathers. Y DNA-matching is therefore only done on men. As surnames in Europe are typically patrilineal in descent the Y-Chromosome can be used to identify men who share a common ancestor. As women do not carry a Y-Chromosome, females who wish to participate require a male MacLennan to provide a sample. The DNA test itself involves a simple swab on the inside each cheek.

To study our maternal line, mitochondrial DNA is sequenced, since we all (men and women) inherit our mitochondria only from our mothers. Because mitochondrial DNA is very short compared to Y chromosome DNA, we have relatively few maternal markers to be tested. Thus the resolution for maternal lines is not as great as for paternal lines.

The DNA testing companies operate in an evolving market. There are a number of offerings in the market for Y chromosome DNA testing, but the only one that should be considered for entry into genetic genealogy through analysis of your “STR” markers is Family Tree DNA (FTDNA). This is because they have a huge number of individuals in their database and have virtually captured the British market and the US, Canadian, Australian (and probably NZ) markets for people whose ancestors emigrated from the British Isles. Since the objective is to compare your DNA directly with everyone else in a database with the largest number of candidate relatives, you want to be sure that you are in that largest database. FTDNA has a superb customer service track record in this area.

A discounted 67-marker FTDNA kit is available to Clan members from FTDNA’s UK representative Alasdair F Macdonald – please go to: www.yourscottishancestry.com/section.php/63/1/clan_maclennan

Alasdair F Macdonald is an Administrator of the “Clan MacLennan DNA Project” at FTDNA.  Contact Alasdair F Macdonald via www.yourscottishancestry.com/contact.php

At the moment, there are 3 stages to DNA testing:

Advice from David H MacLennan, Toronto:

1. The first is to obtain your STR markers (short tandem repeats). FTDNA offers several possible tests at different prices. Don’t consider ordering any less than 67 markers, because any less will be uninformative. If you can afford it now and if you intend to follow your testing through to a logical end, it will be cost saving in the long run to order the 111 marker test, but you can upgrade later. The “67 marker test” may well identify distant relatives within Family Tree DNA’s extensive database.

2. The second stage in your DNA testing will be to look for your terminal SNP (single nucleotide polymorphism), which will put you in a “bin” with othesr who share your terminal SNP. If your terminal SNPs are identical and your STR marker patterns show a high degree of identity, than you will probably be related within a few hundred years. You now have some possibility of finding paper trails that link you. Do not be discouraged by the facts that a) useful birth and death records are very scanty before about 1750 in Britain (they are better in the colonies) and b) that there is a high probability that you will not share a surname (or Clan name) with your closest genetic relatives.

For SNP testing, you will want to consider alternate companies. Yseq competes very effectively with FTDNA for SNP testing and David recommends both for SNP testing.

3. In the third stage, some of you will want to consider having all of the accessible regions of your Y chromosome sequenced. To meet this demand, FTDNA offers their “Big Y” test and Full Genomes Corporation (FGC) offers their “Y Elite 2″ test. Here there are several considerations in choosing a supplier. Big Y at about US$500 is cheaper than FGC Y Elite at about US$700. To date, some 4000 individuals in our area of interest have ordered Big Y, so the database will be huge. Only a fraction of that number have ordered FGC Elite. Why did I order FGC for myself? Because FGC sequences more Y chromosome area and, in my case, uncovered 5 additional SNPs that would not have been uncovered by the Big Y test. As we move forward with DNA sequencing the 4000 Big Y sequencers will be left wondering what do about the fact that they are missing the identification of ~40% of their potential SNPs, whereas I am already home and dry. I suspect that FTDNA will provide a “Big Y 2” that will correct this deficiency, but, in the meantime, consider carefully if you are thinking of doing Y chromosome sequencing now.

Why might people want to do Y chromosome sequencing? First, we have only uncovered a fraction of all of the SNPs that can provide useful information on branch points in our pedigrees. The sequencing tests are turning up new and useful SNPs every day and they are being organized into the trees that eventually will give us our terminal “bin”. When I did my FGC Elite Y chromosome sequence I found that I had 14 novel SNPs that could be tested against my 6 MacDonald and 2 McKenzie relatives. Alasdair MacLennan and Canadian David H MacLennan have 3 “terminal” SNPs that are not shared by our McDonald and McKenzie relatives creating a “MacLennan branch point”. If we had other Y chromosome sequences, we might find a recent MacDonald and a recent McKenzie branch point. Who knows?

Questions and Answers:

Part 1 What can we (MacLennan Clan members) learn from DNA-based genetic genealogy? Click here

Part 2 What can we (MacLennan Clan members) expect from DNA-based results? Click here

Further information about DNA-matching:

Educational material http://www.isogg.org/wiki/Wiki_Welcome_Page

Scottish Project www.scottishdna.net 

David H MacLennan

More about Dr David H MacLennan OC in Canadian Medical Hall of Fame- http://cdnmedhall.org/dr-david-h-maclennan