Apart from the standard uses of personalised medicine in
cancer, recent studies have suggested the importance of genetic sequencing in
patient groups on anticoagulation therapy. The dosage of Warfarin given, varies
between patients and is extremely difficult to predict accurately. This is
shown above in Figure 3. It
illustrates that although there is a common weekly dose which ‘fits’ the
majority of the patients, there are still a low number of patients that are at
the extreme ends of the scale and would need dose adjustments away from the
norm. Since the therapeutic window for Warfarin is relatively narrow, genetic
testing in warfarin-treated patients will allow physicians to offer a dose
which is safer and more effective than current national guidelines. Without an
accurate dose and monitoring, patients may experience
either insufficient anti-coagulation leading to thromboembolism, or excessive anti-coagulation
resulting in haemorrhaging. The variability in the drug-responses are due to
polymorphisms in the following 2 genes: CYP2C9 and Vitamin K epoxide reductase
complex subunit 1 (VKORC1). CYP2C9 is responsible for the metabolism of the warfarin
whereas, warfarin inhibits VKORC1 (Future Medicine, 2017). Since the genetics
of these enzymes varies, so does the concentration in patients’. This accounts
for the differences in response. Particularly in the case of CYP2C9. When
analysed in 200 patients on warfarin therapy, CYP2C9 variants, along with other
factors had a large bearing on warfarin dosing. However, the genetic variation
accounts for 29% of the total variation, with the remaining 71% caused by the
non-genetic factors (Age, current medications etc.) (Wadelius M, 2017). This is
only possible due to the findings from the Human Genome Project. I strongly
believe that in the future, this genetic data could be accessible via a
Patient’s Medication Record (PMR) to help pharmacists’ clinically check a
prescription, thus making any dose-adjustment recommendations. In Canada,
hospitals with a dosing policy in place permit pharmacists to adjust warfarin doses,
a similar approach could be implemented in the NHS. This would save time wasted
contacting the doctor and free up the doctors’ time allowing them to examine
others. There are prospects in the future to allow community pharmacists to
conduct pre-prescription screening prior to dispensing medications. Similar to
the warfarin example mentioned earlier, statins, although first-line for familial
hypercholesterolemia, have variable effects on patients. In the primary care
setting, saliva swab tests could be conducted. A sample could be taken from the
patient’s oral mucosa and placed into a machine which scans through the patient’s
genome in a matter of minutes. The machine looks for a copy of a particular
allele and since the results are obtained quickly, this is a cheap process compared
to the more complex testing required to sequence the entire genome of the
patient. This helps to alter doses, aiding to deliver pharmacogenetic medicines
to patients. (Jamie, 2017).

Like
everything else, not everything about this concept is positive and there are
many obstacles that come along with it. The Human Genome Project has allowed us to venture out into
the relatively new world of modern personalised medicine and the prospect of providing
us with a better understanding of disease mechanisms excites me greatly. New
secure servers would have to be built to house all this data as well as
wide-scale training programmes to educate professionals on how best to utilise
the information. However, the future is looking extremely
promising, as we expect a shift in focus from treatment towards the prevention
of disease. Patients will undergo tests establishing the defective genes, thus
helping to identify effective and well-tolerated treatments as often diseases
have different genetic causes. Further analysis of genetic markers can aid
selection of a treatment with minimal side-effects, a trait sought-after by all
pharma companies. Even though I have
discussed a few of the potential benefits and applications for the future and
how it may lead to preventative strategies, many people will still question the
accurateness of the data obtained and whether it’s worth the anxiety of knowing
they’ll develop a particular disease in the near future.

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