We, for a very long time, have thought that if we had found
the secrets of DNA, we could find the secret of life.
We would be able to know exactly everything about that
human being, because all the information should be encoded
in the genome.
It's the blueprint of life.
Unfortunately, we still don't know exactly how those four
letters' combinations make everything that
we see around us.
So DNA sequence, the genome, is not the whole answer.
And chromosome 11 has helped us to understand that there is
something else besides the sequence of the bases on the
DNA that is important for the expression of these genes.
Now if we think about what happens when a child is born,
then you have one of these little arms that comes from
the mother and one of these arms that
comes from the father.
They come together, and they have in exactly the same
positions exactly the same genes.
We usually always have two copies of the same gene.
And for the most part, they are always both working.
But there are a few exceptions.
One of them is chromosome 11.
One needs to be on, and the other needs to be off.
And the mechanism that makes this copy silent is what
interests me.
It's called an epigenetic mechanism.
It's a way by which the sequence of the DNA that is
there, although intact, not changed, is just marked in a
special way with what we call epigenetic marks.
And those marks tell that sequence not to be
read, not to be on.
And that means that you can have exactly the same DNA in
two cells, as we do, and the same sequence being expressed
in one cell and not being expressed in another cell,
making those two cells different, although they have
exactly the same information, exactly the same blueprint.
What creates this opportunity is what we call epigenetics.
If you think about the DNA, all the bases of the DNA, as
the letters in a book, if you have just the letters, if you
have no punctuation marks, no spaces between the words, you
really don't know how to read that page.
Without the emphasis, without the pauses when you read a
text, you still cannot get the full meaning of
what's going on.
So epigenetics gives a layer of understanding, of
interpretation, of the underlying genetic code or
genome that we all have.
In the case of chromosome 11, it's quite obvious that it is
important to have the epigenetic marks in the right
place at the right time, because it gives you a very
serious syndrome if you don't.
So there are some examples that seem to show that the
environment can affect epigenetic marks in a quite
enduring and long term way.
One example is nutrition.
So the abundance of food for a period of time can have a big
influence in the expression of certain genes.
And that is usually controlled by epigenetic marks.
This can then stay as a memory of that event.
And they can be passed on to our children, and probably to
our children's children as well.
So chromosome 11 was and is a very important tool still to
study how these epigenetic modifications can actually
control the expression of genes.
And the future will tell where this will take us.