GEDmatch for beginners : JonBenet

Until recently GEDmatch was a free genealogy website started and run by two men – Curtis Rogers and John Olson that was primarily used by geneologists. GEDmatch allowed users to upload raw DNA data from consumer genetic testing companies like 23andMe and Ancestry to compare with each other.

But by 2018 forensic investigators had started to use GEDmatch to find criminals. In order to track down the suspect known as the Golden State Killer., investigators created a fake profile on GEDmatch and uploaded DNA from the 1980 crime scene. They got a match to distant relative of Joe DeAngelo, the man eventually arrested as the killer in that case. Since then, the platform has been used to identify many more individuals accused of violent crimes.

The weeks after the news hit about this case created a problem for Rogers and he quickly had to update GEDmatch’s terms of service, to alert users that law enforcement was the searching site.

Some users concerned about privacy did delete their data from GEDmatch, Rogers says. But he’s gotten an “awful lot” of emails thanking him, too. One in particular haunted him. He says a woman wrote that her father was a serial killer, and she wanted her data out there to give the families of his victim’s closure.

How does finding perpetrators of violent crimes through GEDmatch compare with finding them through the FBI CODIS? The first point to make is that different areas of the genome are sequenced in each case, so a DNA profile obtained for submission to the CODIS database is not suitable for submission to the GEDmatch database and vice versa.

When the FBI created CODIS in the 1990s, the way to identify people by DNA was looking for short tandem repeats, or STRs, which are short sequences that can be repeated dozens or hundreds of times in the genome. Each profile looks for STRs in up to 20 locations in the human genome.

In contrast, the DNA profiles on GEDmatch contains information from single-nucleotide polymorphisms, or SNPs at some 600,000 locations in the genome. So although SNPs are not as variable as STRs, you can test a lot more of them.

The forensic investigators however only look at a few dozen to a couple hundred of these 600,000 SNPs. Parabon Nanolabs is one such forensics company that has uploaded DNA from many crime scenes to GEDmatch

Above information was summarised from an article in The Atlantic. Go see the rest of the article – it’s very interesting and an easy read:

And this is a really interesting article. Wow I’m learning so much I didn’t know before

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