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Recognize an individual genome from the rest. Part 2

Today we are going to describe and identify an individual genome analysed from a biological sample of interest.
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For the analysis of forensics samples, you can take any kind of sample. In the biology laboratories people is very happy using blood because this contains part of the cells with DNA only of my own, but we can also use saliva and in reality, anything that contains some tissue may be used. Now we know that we have cases of being able to do the whole genome sequences for ancient DNA samples that may have more than 40 thousand years of age, meaning that the potential of getting DNA is really very strong in ancient and degraded samples.
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And in these places what we try to do is to look for specific STRs (Short Tandem Repeats or microsatellites again) and then what we are going to do is to count the number of repetitions we have in our genome. So, STRs are this sets of two, three, four, five nucleotides repeated many times, and this is extremely variable. So, all of us, if you go to a specific STR, you’ll see that you are heterozygote and the number of repeats is for example ten and twelve and another individual has eight and twelve and so on. And this is what is mainly used to recognize the individuality of a given genome.
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In the lab, this is possible to be obtained looking at the length of the DNA fragments containing this variable and the peaks show the length, meaning that it’s possible to recognize the number of repetitions that each individual has. With this number of repetitions, then it is possible to use that in a paternity case or recognizing whether a given sample comes from an individual or from another.
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The idea is very simple: if it’s the same, it’s you. If it’s not the same, it’s another one. As simple as that. So, we have in this case the STRs that are being analysed and what has been possible to do do is to have a common set of STRs that are being used by the forensic community all over the world. In some cases, these STRs are also interesting to be looked at the Y chromosome because there are, in this case, specific variants in the Y chromosome. In the genome it should be possible also to look for traits, and in the 23andme results there are some specific traits,
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but there is a challenge still not well accomplished in which the point is: would it be possible to recognize the facial traits of individuals through the genome? We think that it will be feasible, but we have to recognize that still now has not been fully achieved. There are several works trying to do that, in some cases it’s very simple, so to recognize from the genome whether a person is black or is of European origin that’s very simple, but to recognize the facial traits to draw the face still is a challenging point.

Today we are going to describe and identify an individual genome analysed from a biological sample of interest.

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Why Biology Matters: The Genome and You

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