Dr. Brown studies the genetics of alcoholic liver disease.
We can clearly explain these three different experiences of alcohol
on the basis of genetic variation.
That’s because the enzymes that break down alcohol in our bodies
are determined by our genes.
Alcohol is first converted into a chemical called acetaldehyde,
which becomes toxic at high concentrations.
The acetaldehyde is then broken down mainly in the liver
by second enzymes into carbon dioxide and water.
These can be eliminated from the body.
So, we got the results.
Alice and Joe, you guys have the same variant.
And you are different to Glenn.
So, you guys do not get rid of the alcohol as quick.
65% of Eastern Asians and 5% of the Europeans have the genes
that code for the slow metabolising enzyme at this first stage,
meaning that alcohol stays in their systems for longer.
But then we do see a difference in this second enzyme
that gets rid of the toxic byproduct of the alcohol, the acetaldehyde.
And Alice you have a typical genetic profile for this,
so you get rid of it as fast as anyone else.
But Joe, this is where you have a variation in your genes,
that means you don’t get rid of the acetaldehyde,
which is what we are seeing, right now, looking at you.
This is living genetics. This is a great example.
And I think, you know, what Joe’s body is doing
is telling him to stop drinking.
What we see in people with that slow gene
is that if they carry on drinking through it
for social pressures, despite the sideeffects,
then they are putting themselves more at risk of liver disease.
And it’s thought that it’s this toxin,
this acetaldehyde produced, as we break down alcohol,
which makes Joe’s hangovers worse than most.
But in Glenn’s case, his enzymes work normally.
So, he breaks down both the alcohol
and the acetaledhyde at the typical rate.
So, if his enzymes are normal,
how come he can drink much more alcohol
than most people without feeling it?
There is an alternative pathway,
which actually breaks down alcohol by a different method.
What’s different about this pathway is that it’s inducible,
there’s no limits to the amount of alcohol
that you can carry on passing down that pathway.
This secondary metabolising pathway can be switched on
when we drink faster or in larger amounts than the body can cope with.
It works like an overflow system.
This allows the additional alcohol to still pass through the liver.
So, Glenn has induced or switched on
this second way of dealing with alcohol.
Correct. It goes from the gut to the liver, it’s broken down.
It never gets into the bloodstream.
So, it never has that effect on the brain,
which is effectively where we feel drunk.
Does this mean the alcohol is less dangerous,
in terms of the effects on Glenn’s liver than it would be
for someone who doesn’t drink that often or that regularly?
Okay, the alcohol is still being broken down by the liver,
and a breakdown products of the alcohol
are what’s causing the damage to the liver tissue.