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My name is Anke Hinr.
I'm going to present you
some additional data
pertaining to monogenic
forms of obesity.
In the first part,
you already heard
a lot of data pertaining
to the major gene for obesity,
the leptin gene, with mutations
usually leading to severe
forms of extreme obesity.
And now we've
switched to a gene,
which is working
in the same cascade
of the weight regulation.
It's called the melanocortin-4
receptor gene.
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The leptin signal is received
in the central regions
of the brain.
And the melanocortin-4 receptor
is one of the effectors
of this leptin signal.
In 1997, the first knockout
mouse model was published,
showing the relevance
of this gene
for body weight regulation.
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Mice not expressing
this receptor
or only heterozygously
expressing the receptor,
and you can see
the weight charts of these mice,
on the upper part of this slide,
you can see the females
with the lack of this receptor.
And in the lower part
of this slide,
you can see
the male mice not harboring
or only harboring one copy
of this melanocortin-4 receptor.
So if you look
at the upper part,
then you see
the weight development
of the wild type mice,
indicated by the +/+ sign.
And on the other hand,
the -/- or +/- mice
display much higher weight
than the wild typic mice.
And you can also see
that the heterozygous mice,
the weight of these mice
are sort of in between,
at least in the female sex,
in between the knockout,
in the wild type mice,
and for the males
there is an overlap
between the wild type
and the heterozygous.
This also already
indicated that mutations
in this gene leads to
a dominant form of obesity.
So lack of one copy of
this gene is already sufficient
to lead to
an increased body weight.
And in the meantime,
a lot of mutation screens
had been performed
for this gene.
And a lot of obese and
normal weight individuals
had been screened
for mutation.
