An open community 
of Macintosh users,
for Macintosh users.

FineTunedMac Dashboard widget now available! Download Here

Topic Options
#28589 - 04/07/14 07:50 PM DNA Searching
ryck Offline


Registered: 08/04/09
Loc: Okanagan Valley
Does anyone have any experience with searching background using DNA?

Here's the challenge: A man has never known who his birth father was, and no longer has any relatives who could shed light. He has children who are interested in learning about their ancestry such as racial background, nationality, et cetera. He wants to help but has no understanding of DNA research. He also has concerns about validity, and how he would avoid hucksters.

Any thoughts would be appreciated.


Edited by ryck (04/07/14 08:01 PM)
_________________________
ryck

iMac (Retina 5K, 27", 2017), 3.4 GHz Intel Core i5, 8GB RAM, 2400 MHz DDR4
OS Mojave 10.14.6
Canon MX710 Printer
Epson Perfection V500 Photo Scanner
Carbon Copy Clone on 1TB LaCie USB-C
Carbon Copy Clone on 500GB OWC Mercury OTG Pro

Top
#28730 - 04/26/14 08:34 AM Re: DNA Searching [Re: ryck]
Ira L Offline


Registered: 08/13/09
Loc: California
My wife has a client for whom she did some DNA research (using the client's DNA of course). The only things that were commercially available to the public/my wife provided information on the "proclivity" towards certain illnesses. Your DNA won't show nationality, although if certain things show up, like the person is a Tay-Sachs carrier, then it is not unreasonable to conclude that somewhere, someone was of Eastern European Jewish origin.

Overall, the client was not that impressed with the results. On the other hand, if you have access to law enforcement databases or something similar, you might get more detailed feedback. grin
_________________________
On a Mac since 1984.
Currently: 27" iMacs, Macbook Air, macOS 10.14.x,; iPhones, iPods and iPads galore!

Top
#28734 - 04/26/14 09:16 AM Re: DNA Searching [Re: ryck]
alternaut Offline

Moderator

Registered: 08/04/09
Thanks to Ira for reviving this topic. I had started a brief reply some time ago, but was interrupted before finishing and promptly forgot about it. FWIW, here goes:

You can get some background info about ancestry testing (including some links for further reading) from the US National Library of Medicine article What is genetic ancestry testing? In general you need to know that with genetic testing you only get answers for the questions you ask (read: are certain DNA sequences present?), not for those you don't ask. That seems a bit like kicking in the proverbial open door, but as there are a great many such questions to ask, genetic testing tends to be a (far from exhaustive) sampling study. That can still be conclusive with regard to some questions, but that depends entirely on those questions.

In general though, it seems to me that quite a few people aren't particularly impressed with the results of the 'standard package' many vendors are offering, perhaps because they didn't realize exactly which questions these packages were answering, and had 'inflated' expectations. It may well be that one of those 'generic' tests, followed by a more specific one based on the results of the first is the way to go.
_________________________
alternaut moderator

Top
#28753 - 04/26/14 05:07 PM Re: DNA Searching [Re: alternaut]
ryck Offline


Registered: 08/04/09
Loc: Okanagan Valley
Thanks for the link…..looks like some very interesting reading there.

Clearly, if the answer you get is so dependent on the question you ask, this is not an undertaking to embark on without considerable thought about the questions. Good to know….I was one of those people who thought you could simply submit a sample and get back information such as having a connection to a distant group.


Edited by ryck (04/26/14 05:13 PM)
_________________________
ryck

iMac (Retina 5K, 27", 2017), 3.4 GHz Intel Core i5, 8GB RAM, 2400 MHz DDR4
OS Mojave 10.14.6
Canon MX710 Printer
Epson Perfection V500 Photo Scanner
Carbon Copy Clone on 1TB LaCie USB-C
Carbon Copy Clone on 500GB OWC Mercury OTG Pro

Top
#28754 - 04/26/14 05:08 PM Re: DNA Searching [Re: Ira L]
ryck Offline


Registered: 08/04/09
Loc: Okanagan Valley
Originally Posted By: Ira L
On the other hand, if you have access to law enforcement databases or something similar, you might get more detailed feedback. grin

Hmmmmm…….now there's a shortcut with possibilities. wink

Thanks for the information about your wife's experience with the process.
_________________________
ryck

iMac (Retina 5K, 27", 2017), 3.4 GHz Intel Core i5, 8GB RAM, 2400 MHz DDR4
OS Mojave 10.14.6
Canon MX710 Printer
Epson Perfection V500 Photo Scanner
Carbon Copy Clone on 1TB LaCie USB-C
Carbon Copy Clone on 500GB OWC Mercury OTG Pro

Top
#28773 - 04/27/14 08:51 AM Re: DNA Searching [Re: ryck]
alternaut Offline

Moderator

Registered: 08/04/09
Originally Posted By: ryck
I was one of those people who thought you could simply submit a sample and get back information such as having a connection to a distant group.

That may still be possible, assuming your distant group is sufficiently 'different'. As the global population intermingles more and more, these differences tend to diminish, and matches may mean less than they used to.

To elaborate a bit on what I mentioned above (and without pretending to be either complete or exact), the 'questions' asked in genetic testing boil down to establishing the presence (or absence) of specific stretches of DNA, a long chain molecule most of which manifests as chromosomes when tightly wound up for storage. Such stretches, sequences of nucleotides (the molecular building blocks of DNA), are part of longer and functionally discrete portions of your DNA, referred to as 'genes'. The total of those is called 'genome'.

The stretches selected for tests ('probes') tend to be associated with properties of interest (ethnic/racial origin, physiological traits, susceptibility to disease etc.). The fewer probes used, the more there is an element of interpretation in analyzing the test results, particularly when the question relates to multi-factorial gene effects, and many are. Things get even more complex when you realize that genes and their expression may be influenced by environmental factors and behavior. Finally, it's important to understand that a genome is not so much a blueprint but a recipe, subject to substitutions due to circumstance, etc. In summary, the bottom line in a good genetic analysis is (1) a judicious choice of (2) a sufficient number of (3) known good probes.

Because of the great variation* possible in the DNA chain molecule constituting genes, even apart from the fact that certain variations or combinations thereof may not have any noticeable effect, these associations aren't necessarily absolute, but are best expressed in percentages (of a full match). That's also why genetic probes often are selected from variable stretches, to maximize finding specific differences. The more probes you test or the more genes you compare, the greater the chance that you are found to be 'different' from others, until you arrive at the—presumably unique—individual: yourself.

*) Note that human genetic variation is limited to less than about 0.1% of one's DNA. But because the human genome is so huge (~ 5 billion nucleotide base pairs), that still amounts to very large numbers of possible combinations.
_________________________
alternaut moderator

Top
#28791 - 04/27/14 05:04 PM Re: DNA Searching [Re: alternaut]
ryck Offline


Registered: 08/04/09
Loc: Okanagan Valley
Wow, and thank-you. Clearly this is going to be a very educational undertaking. I really appreciate that you took the time to get this into lucid, bite-size chunks.
_________________________
ryck

iMac (Retina 5K, 27", 2017), 3.4 GHz Intel Core i5, 8GB RAM, 2400 MHz DDR4
OS Mojave 10.14.6
Canon MX710 Printer
Epson Perfection V500 Photo Scanner
Carbon Copy Clone on 1TB LaCie USB-C
Carbon Copy Clone on 500GB OWC Mercury OTG Pro

Top

Moderator:  alternaut, cyn