Posts tagged ‘mitochondrial’
I started down the DNA learning path several years ago. My Dad’s father was adopted, & when I eventually found his birth certificate it contained no information about his father. An unusual middle name and circumstantial evidence suggested someone, but with no documentary evidence, DNA seemed a way to test my theory.
I found a grandson of this possible ancestor – son of a son, so a good candidate for y-chromosome DNA comparison with my father. I asked – if I paid for it, would he be willing to have his DNA tested to compare with my father’s DNA? He said yes, but unfortunately the test proved that he and my father were not related. (DNA is often better at disproving rather than proving relationships.)
I used the company Family Tree DNA, which has the largest database for testing and comparison, and now that I am registered, I am advised when others match my Dad’s DNA. I hope that one day I will find someone with the right DNA,who had an ancestor in the right place and at the right time.
Some time later, I had the opportunity to speak to Megan Smolenyak about my problem & confirm my method. I asked Megan for her advice about which company should I use to test my Mum’s DNA.
Females don’t have y-chromosomes so cannot have the y-DNA tests done. However humans have other DNA outside the cell nucleus, called mitochondrial DNA (mtDNA). Mothers pass mtDNA to all their children, but only their daughters pass it on. I wanted my Mum’s DNA to be tested now and also stored for the future, for as-yet-undeveloped tests. Forensic scientists use mitochondrial DNA now, but for genealogists mtDNA is mostly only used for deep ancestry testing, not for finding ‘recent’ ancestors (those in a genealogical timeframe).
Megan suggested that I have my mother’s DNA tested with the company 23andMe, as they were developing new tests and could offer more information about female ancestors. 23andMe tests give information about genetic health issues, in addition to genealogical ancestry matching – so I took that advice.
These 2 companies that I had used (23andMe & FamilyTreeDNA) offer very different information in their test results. Results from the FamilyTreeDNA tests are tables of numbers, indicating the DNA at specific genetic marker points. There is also a YSearch database for comparing results, and even people who have had their DNA tested with other companies can search this freely – you manually enter the numbers (alleles) at various marker locations and see if the results match anyone in the YSearch database.
The results from 23andMe gave information about genetic health risks and tendencies and general DNA groupings – it required a bit more delving to actually find the numbers that correspond to the (mitochondrial) DNA markers.
Around a year ago, both these companies announced new tests involving autosomal DNA. 23andMe call this ‘Relative Finder’ – FamilyTreeDNA call it ‘Family Finder’. Humans have 23 pairs of chromosomes in every cell nucleus – 22 pairs of autosomes and also another pair, the ‘sex chromosomes’ (XX for females, XY for males). The autosomes contain bits of DNA inherited from all your ancestors, not just from all-male or all-female lines. You share larger pieces of DNA in common with close relatives, and smaller bits of autosomal DNA with relatives less closely related.
Both males and females have this autosomal DNA, so now you can find relationships with anyone sharing any common ancestor, not just the all-paternal or all-maternal lines. This new autosomal DNA test has thrown up some new possibilities and new candidates in the search for my father’s father’s heritage. (We already have found a close relative with interesting possibilities.)
However, back to the initial subject. The company 23andMe is offering a special price for the next few days, and some Facebook friends decided to take advantage of it. I agonised whether I should join them, given that I already have tested my father’s DNA as well as my mother’s mitochondrial DNA.
In terms of autosomal DNA, although the test is new, I suspect that the company FamilyTreeDNA is likely to have a bigger database for comparisons. (For me the main value of DNA tests is looking to match with others, and so larger databases are better.)
But 23andMe gives other information – about genetic related diseases – in addition to the study of ancestry. I have decided that both companies’ tests are of interest to me. So now I too have taken advantage of the current special price, and will get my own DNA tested.
Of course there are many other testing companies, and websites with information about DNA. I give talks about ‘DNA for Genealogists’ (my handout can be found on my website). The handout contains information about various testing companies and their information pages, as well as other sites with DNA tutorials, mailing lists and even a DNA Wiki.
For now though, I have joined the ranks of those waiting for a test tube to be posted to me, so I can take the next step in this DNA journey.