Richard III and DNA testing

[davidft]

Archaeologists are currently digging up a car park in Leicester in search of the remains of Richard III of Bosworth fame. They have now found some bones which are going to be DNA tested.

According to the news this lunch time they are going to compare the DNA from the bones with that of a 17th generation descendant of Richard III’s sister. How is that going to work? It cannot be a Y-DNA comparison as Richard’s sister won’t have any. If it’s a mitochondrial DNA (maternal line) test will that provide any conclusive results? Mitochondrial DNA analysis as I understand it is much less precise and cannot conclusively prove a connection between Richard III and this 17th generation from Canada. All it can do is rule out a non connection.

Have I got it right or am I missing something in this DNA testing malarkey?

[shanew147]

They dont have to use mitochondrial or just Y chromosome DNA - other DNA is available from cell nuclei i.e. the other 22 pairs of chromosomes. Even small fragments can be amplified using PCR (Polymerase Chain Reaction) or similar and analyzed using Electrophoresis to produce to DNA results like those you see on CSI etc

see : PCR - example of Electrophoresis results


Shane

[Alexander.]

Though they could use autosomal DNA, it would be extremely difficult to prove a relationship since there are so many generations between Richard III and his 17th great nephew. They would only share a microscopic percentage of autosomal DNA (something like 0.5¹⁷ = 0.000763%).

Fortunately, Richard III's 17th great nephew is a direct descendant of his sister on the maternal line, meaning that they can use mitochondrial DNA. A benefit of this is that there's lots of mtDNA in our cells, so it's more easy to extract from ancient skeletons than nuclear DNA.

I'm sure they will do a very high level test (many more markers than you can easily test through a commercial company). While it is impossible to prove that two people were related using DNA, and there certainly will be differences in their mtDNA because of the 16 intervening generations, the test should be able to show whether there is a chance that the remains are related to the descendant. As you say, DNA is very good at disproving relationships, but not so good at proving them (because there is always the possibility that sequences could match by chance).

Alexander

[davidft]

Fortunately, Richard III's 17th great nephew is a direct descendant of his sister on the maternal line, meaning that they can use mitochondrial DNA. A benefit of this is that there's lots of mtDNA in our cells, so it's more easy to extract from ancient skeletons than nuclear DNA.

I'm sure they will do a very high level test (many more markers than you can easily test through a commercial company). While it is impossible to prove that two people were related using DNA, and there certainly will be differences in their mtDNA because of the 16 intervening generations, the test should be able to show whether there is a chance that the remains are related to the descendant. As you say, DNA is very good at disproving relationships, but not so good at proving them (because there is always the possibility that sequences could match by chance).

Alexander

BIB - Thank you. That was what I was thinking. They can't actually prove it, they can say there is a high possibility or say there is no possibility.

[davidft]

see : PCR - example of Electrophoresis results

thank you for the link, which I have read - if not fully understood.

i can see that technique working with close relatives eg son, mother  or grandparent, grandchild and believe that was possibly the techniques use on the recent channel 5 series identifying some of the close relatives of Tutankhamen.

However i didn't think it was a reliable technique for comparing say over 17 generations when multiple natural variations in the DNA could occur. So at best it would give an inconclusive result.

(I think Freckneales post has explained the position I was trying to get to)

[davidft]

They could do a Y-DNA comparison.

The Duke of Beaufort is a direct male line descendant of Edward III as was Richard III so there would be male candidates out there to compare Richard III's Y-DNA with (assuming its him and that the reputed fathers of all the Beaufort heirs are correct)

[Lydart]

I heard that the skeleton they are testing also had a somewhat curved spinal deformity .... or is that just Shakespeare ??        

[davidft]

Yes that is true which is a bit ironic as for years the Richard III society have said he wasn't a hunchback and that was all Tudor propaganda ......

[alpinecottage]

He wasn't a hunchback, as Shakespeare alleged, but he did have scoliosis, which is a sideways curvature of the spine.  Apparently the skeleton also has scoliosis.