Mitochondrial diseases
cover a wide range of conditions
caused by genetic mutations.
In the UK alone, they affect thousands.
Mitochondria are the ‘powerhouses’ of the cell.
They use a process called
‘oxidative phosphorylation’ to generate energy.
But a mitochondrion
is a complex piece of machinery,
and a lot can go wrong.
It takes around 1500 proteins
for mitochondria to function,
and problems with many of these
can lead to disease.
The cell’s nuclear DNA creates
all but 13 of these proteins.
The rest are coded for by the DNA
in the mitochondria themselves.
And mutations in either can cause problems.
A cell has just one nucleus and many mitochondria.
All a cell’s mitochondria
contain their own DNA.
If a mutation affects mitochondrial DNA
some might be healthy: others, defective.
And different cells can have different numbers
of defective mitochondria inside them.
That means that some cells
may be less affected than others.
The diseases caused by damaged mitochondria
can also be varied.
They can affect any organ or tissue.
And they can appear at different times through-out life.
For example, Leigh syndrome
is the most common type to develop in childhood.
It can affect patients in a number of ways,
including loss of skills, epilepsy,
and problems with muscle function.
Mutations in over 75 genes –
in both nuclear and mitochondrial DNA –
can lead to this syndrome.
So what can be done to tackle
mitochondrial diseases, like Leigh syndrome?
Treating patients is difficult.
But in some cases, the disease can be stopped
before it’s passed on.
Mitochondria are inherited from the mother.
If the mutation is in the mitochondrial DNA,
this inheritance can be blocked.
One approach is to combine the nuclear DNA
from an affected egg cell
with healthy mitochondria from another woman.
The embryo would then have nuclear DNA
from the original mother and father,
and mitochondrial DNA
from the egg cell donor.
This has led some to call such potential infants
‘three parent babies’.
This technique is still very new.
But it has recently been approved in the UK.
It may be a controversial approach,
but techniques like these
could finally help combat these devastating diseases.
