Wednesday, November 11, 2009

Find half-siblings through NEW DNA database


Exciting news today to report........

Lindsay has found her first half-sibling!!!!!

ANDDDDDDD......myself and Damian (Donated Generation) are starting a FREE database for donor conceived adults to submit their autosomal and/or Y-STR DNA tests to be scanned against everyone else in the database to search for potential siblings.

Now, for many of you you're thinking isn't that what they're doing in the UK with the UKDonorLink?!? My answer is YES and NO. See, UKDL has made an executive decision to ONLY notify offspring that have a match that is at 99% probability. That means there could be tens (maybe hundreds, I'm not sure how many members are in UKDL currently) who are NOT being contacted of possible siblings that score a combined index over 1.0 (threshold for relatedness) simply because their results are not 99% conclusive.

Even here in the USA, courts accept 90% probability of siblingship as legal, so the UKDL administration is simply not holding up their end of the project.

So, Damian and I propose a free database where any individuals that are found to hold a combined siblingship index OVER 1.0 will be contacted!!! It would then be up to those two individuals to decide if they want to continue on to a professional test based on other knowledge (place and time of conception, clinic, sperm bank, etc). We do NOT advise any "matches" to take our results as proof. We wish to act as a screening tool so that offspring are not put through the emotional and financial hardships of routinely going through DNA tests to find family.


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A bit more about the combined siblingship indexes:
The combined siblingship index is a series of special equations (that Damian and I cracked) that take into account the frequency of different loci's alleles in the general population. Basically, this means that some alleles are VERY common, say 50% of the general population. That means if two potential siblings share this allele it does not mean much, and receives a very low index.

Compare this to an allele that is very rare in the population, say 0.03 (only 3 out of 100 people have this allele). In this case, the index would be a larger number because the chances of two unrelated individuals sharing this allele is more unlikely, and the chances of two people who share this allele being related increases. Remember, we inherit one allele from each parent.

So, on a 15-loci DNA test, each of the 15 loci that have an allele that is shared, that index is going to be greater than 0.5 (often around 1.5-5.0 on average), and for loci that there is no allele shared the index stays at 0.5. This is because there is a 50% prior probability. The indexes for each loci are then multiplied together and that forms the combined siblingship index.

1.0 is the threshold. This means that anything below 1.0 is conclusive that there is non-relatedness between the two individuals. Anything that breaks the 1.0 combined siblingship index means it SUGGESTS relatedness, with the higher the index the more likely it is that the two individuals are actually related. I say suggests because half-siblingship tests cannot be 100% conclusive. Half-siblings share 25% of their DNA, so on a 15-loci DNA test with two alleles at each loci, that means that half-siblings share on average one allele on only 7-8 loci!!! This is why, unlike paternity tests where a child must have an allele present that matches one of the alleged fathers at EVERY loci, these frequencies and special equations are IMPERATIVE!!

It is also imperative to have mother's DNA samples as well if at ALL possible, as it excludes which allele came from her, and thus increases the index for an allele that matches if it HAD to have come from the alleged shared father.
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This database idea came out of the experimenting that Damian and I did in response to receiving previous DNA test results from a potential sibling. After assessing both her and my results I realized that we matched at 10/15 markers!! However, I did not know if this was significant or not, so I set out to find the frequencies and equations to determine a siblingship index. After finding several articles, databases, and programs, Damian and I together toyed with the information and came up with indexes anywhere from 0.8 and 1.62 (without mom's DNA) to 100, 147, 235, and 315 (with moms alleles excluded), using different programs, equations and frequencies!! We knew we had a HUGE range in results and that a professional test was necessary to confirm the analyses we did.

We also were missing my mom's alleles on 4 markers that had not worked in our last DNA test....if all 4 continued to match our index would be much higher. HOWEVER, if all 4 of those markers that we matched at were found to no longer be a match (because the allele I actually inherited from my mom was the one I matched with). In this "worst case scenario" I calculated our index to be about 5.8. This would NOT be conclusive or significant, but it would be over 1.0.

We realized however, that if the professional results came back in the same ballpark, that we had cracked it. We could essentially analyze DNA results!!

When the results came in this morning everything was confirmed. My new half-sister and I are 578 times (99.8% chance) more likely of being half-siblings than non-related!!! And Damian and I discovered a way to pre-test for siblingship and have a basis for a DNA database for offspring worldwide.

So what we propose is a database that will provide offspring with direction and a sense of hope. Direction into whom to do further confirmation tests with, and hope that despite not having any information that there's still a chance of finding siblings.

We want to provide the services that no one else has been able to give to donor conceived adults. UKDL has dropped the ball. They cannot be trusted to give this vital information to offspring even when they hold the answers. CaBRI, the non-profit X and Y chromosome database for offspring, it can only find siblings of the same sex. The registries cannot fulfill the needs of older offspring who do not have donor numbers. And the infertility industry has spent incredible time and energy refuting, demeaning, and denying donor conceived adults for several decades now, and it is time that we take control over governments, DI mommies, and the industry, and put our futures back into our own hands.

Contact Lindsay here if you would like more information or would like to submit DNA test results!


Update:
See more about siblingship DNA tests, and the Combined Sibship Index in my post "Even more about DNA half-siblingship tests"

4 comments:

paragon2pieces said...

congratulations on finding your half-sibling! i am so happy for you :)

Lindsay said...

thanks!!! :o)

nancy said...

The technology is improving fast and it would not take long before the above statement comes true.

Vinnie said...

Hi -- It's been a while since you posted this, but I just saw it and I am happy to hear you found a half sibling. My wife and I found a half-sister by the same donor as my DI son about 2 years ago, and have become friendly with the family (both my family and hers have been open with the children about their DI story since they were born, so as never to have to "drop a bomb"). It is an interesting relationship, pleasant in the moment but really kind of preparatory, entered into so that my son and his half sister will have an opportunity to make of it what they wish when they are older. We hope it will be a positive thing for my son, especially if he is troubled by the DI story as you are and even if not. (It doesn't bother him now and I hope it never does, but he's barely 4, so I wouldn't close the book on that yet, especially given Damien's experience.)