Therapy and Cystic Fibrosis.
Therapy = helping people with mutated or faulty genes to alleviate
the symptoms of their disease.
who have cystic fibrosis (CF) have a faulty gene in their
cells. This gene codes for a carrier protein in the cell membrane
protein helps Chlorine ions (Cl-) leave the cell taking water
with them by osmosis.
CF patients not enough water leaves the cell and the mucus
made by the cells becomes very thick. This thick mucus has
a particular effect in the cells of the lung. It stops gas
exchange in the alveoli and blocks all bronchi and bronchioles.
This makes the sufferer cough, liable to chest infections
and reduces their breathing rate.
mucus may also block sperm tubes in male patients and fallopian
tubes in females. It can also upset digestion of food in the
sufferers of CF die before reaching 30 years of age.
looked to treat CF patients by cloning normal CFTR genes and
inserting them into the sufferer. To work the CFTR gene would
need to be inserted into the chromosomes of the sufferers
cells via a vector.
vectors used so far are either viruses or liposomes in sprays
inhaled into the nose or lungs.
are attenuated (killed/made harmless) viruses that do not
cause disease but carry the CFTR gene.
viruses are capable of inserting the recombinant DNA into
the hosts DNA so that the vital CFTR protein can be produced
in the cells.
the donor DNA has not proved able to insert itself and remain
stable in the hosts DNA. Regular treatments are needed.
patients have also had severe side affects to the viruses
used and the treatment.
are microscopic fluid filled droplets made of oil and water.
They contain the recombinant CFTR plasmids in the centre of
the droplet. These liposomes can be coated in sugars as receptor
molecules to allow them to be taken up by the lung cells.
However, although many of the liposomes are taken up and some
CFTR protein is found to be translated, very few of the CFTR
genes seem capable of recombining with the DNA in the nucleus
of the cells.
treatment needs to be repeated regularly to ensure the CFTR
protein is produced in the sufferers cells.
in summary :-
The treatment needs to be repeated regularly. The patient
is not cured for life.
Treatment is expensive and not widely available.
There has been little real success in trials so far.
There is much controversy over whether it is right to try
to insert normal/correct genes into humans. Many are worried
we will not just stop at diseases and move onto other characters
we may want to improve!