That was great! If you keep this up, I may actually understand the DNA tests some day.
David Mello On Nov 8, 2012, at 11:19 AM, Cheri Mello <[email protected]> wrote: > Hi Paul G, > > I'm sorry about that. I guess in my rush I forgot to mark the email so I > could go back later and answer in more detail. Thanks for the reminder! > > There are different types of DNA testing. We've all heard about criminals > and their DNA being run through CODIS (COmbined DNA Index System) - at least > in America. These are unique, identifying markers where scientists can say > it was a 1 in a trillion chance. We don't use these for genealogy. We want > to know what unites us and makes us alike, not unique. > > There are also tests on the market for medical DNA testing. You can find out > if you are more at risk for certain diseases. Family Tree DNA (FTDNA) is not > involved in medical DNA testing. > > The 3 tests on the market for genealogy are Y-DNA, mtDNA (mitochondrial DNA), > and autosomal DNA (atDNA - FTDNA calls it their Family Finder). Not all > companies that use DNA for genealogy offer all 3 types of testing. FTDNA > does. They've been in the business of DNA for genealogy exclusively since > 2000. They have a very reputable advisory board. They have the largest > database. Those are some of the reasons why the Azores DNA project was set > up with FTDNA. Now for the 3 types of testing. > > 1) Y-DNA: The Y chromosome is part of the 23rd pair, or the sex chromosome. > It is what makes you a man and me a woman (the other 22 pairs are autosomes > and I'll discuss them in # 3 below). For you to be a man, your 23rd pair is > an XY. I'm an XX, being female. What this means is that you got the X from > your mom and the Y from your dad. You dad, being male, was also XY. He got > the X from his mom and the Y from his dad. Your grandfather, being male, was > also XY. He got the X from his mom and the Y from his dad. So the Y > chromosome follows the top of your pedigree chart, or a strict, all-male > line: Your father's father's father's father all the way back in time. Since > I am a female and have no Y, I had to find a male in my line to take the test > (my dad). Now, if you want to focus strictly on 1 line, this is the DNA test > to take. (And for those who want to know why they don't test the X of the XY > pair...the X did come from mom, who was XX. Which X did your mom give you? > Her mom's or her dad's? The scientists can't tell so we don't use it for > genealogy testing). > > 2) mtDNA (mitochondrial DNA): The mitochondria is the powerhouse of the cell > and it houses mtDNA in its nucleus. There's a lot of of and it is very hardy > and can withstand time and deterioration. A mother (female) passes it down > to her offspring. So either men or women can test their mtDNA. It traces the > mother's mother's mother's line, or the bottom of you pedigree chart. All > women, all the way back in time. The strict, all-female line. However, > because of its hardiness, it rarely mutates. It's much harder to use it to > for genealogical purposes. It's best use would be if you and I were in the > same freguesia and we see our 5great grandmas (who are our mother's mother's > mother's mother) being godmothers to each other's kids and we really think > that they are sisters, but the records run out. If we both did a DNA test > and had the same mutations, then we could be sure. But just to do it and > hope for a match without a location or theory is slim. However, the 1st DNA > match made in the Azores DNA project was through mtDNA. Both participants (a > man in Brasil and a woman in California) had a rare mutation and were in > adjacent freguesias. Research later proved they were related. > > 3) atDNA (autosomal DNA/Family Finder): This involves the other 22 pairs of > autosomal DNA. You got half your DNA from mom and half from dad. Your > parents got half from their parents; therefore, you have 25% of your > grandparents DNA, 12.5% of your greats DNA, 6.25% of your 2 greats, 3.125% of > your 3 greats, etc. Because this is looking a a cross-section of DNA that > recombines, it covers all of your pedigree chart, back approximately 200 > years (or 200 years from the person taking the test. My dad, born in 1934, > has DNA matches that I don't have because his DNA is taking him back to the > early half of the 1700s whereas my DNA only goes back to the mid-1700s). > Now, if you and I share the same 3 great, we should have about 3% of their > DNA in our genes. However, we don't have the SAME 3%, but different > fragments of it. And if "Fred" shared the same 3 great, he may not even show > up in my matches, but in yours because he has a different fragment that > matches one of yours, but not one of mine. So even though this uses our > complete pedigree chart back about 200 years, we need to have MOST of our > lines back, and we need to have it uploaded to our FTDNA page so we can look > for the common ancestor. Or if we are not back that far, at least the > freguesia so we can have a clue. We may not know initially which 3 great we > have in common, but with a little detective work, a few emails, and a lot of > patience, we can figure it out. > > So, do you want to focus on one line at a time? (Your father's father's > father's or your mother's mother's mothers)? You will probably wait a few > years for a significant genealogy DNA match (especially if your Y is > Portuguese). Or do you want a cross-section or overview of your DNA? If you > are 100% Portuguese, you will have approximately 2-4 pages of matches (at 10 > people per page). If you are a mixture, you will have more pages of matches > (my dad is half Portuguese and is up to 19 pages of matches now. About 2 to > 4 of them are Portuguese and the remaining are British Isles type surnames > from his mom's tree). If you go for Family Finder, it will take time to wade > through the matches and figure out exactly how you match these people. > > Hope this helps. If you have any further questions, let me know. > Cheri Mello > Listowner, Azores-Gen > Researching: Vila Franca, Ponta Garca, Ribeira Quente, Ribeira das Tainhas, > Achada > -- > To unsubscribe from this group, send email to > [email protected]. Follow the confirmation directions when > they arrive. > For more options, such as changing to List, Digest, Abridged, or No Mail > (vacation) mode, log into your Google account and visit this group at > http://groups.google.com/group/Azores. Click in the blue area on the right > that says "Join this group" and it will take you to "Edit my membership." -- To unsubscribe from this group, send email to [email protected]. Follow the confirmation directions when they arrive. For more options, such as changing to List, Digest, Abridged, or No Mail (vacation) mode, log into your Google account and visit this group at http://groups.google.com/group/Azores. Click in the blue area on the right that says "Join this group" and it will take you to "Edit my membership."
