Before initiating abacavir, an anti-retroviral, for a newly diagnosed HIV
positive patient the nurse practitioner orders HLA-B*5701 allele genetic
testing. The test confirms that the patient carries the HLA-B*5701 allele.
The HLA-B*5701 is genetic testing used to determine the potential risk for severe
side effects from the antiviral medication abacavir (De Spiegelaere et al., 2015).
The HLA-B gene has an impact on how the immune system responds and
recognizes various pathogens while mediating hypersensitivity reactions (De
Spiegelaere et al., 2015). If a copy of the HLA-B*5701 is positive, it determines
there is at least one copy of the allele. This test is run by obtaining a sample of the
patient's saliva or blood. Abacavir is a nucleoside reverse transcriptase inhibitor
used as an antiretroviral therapy in HIV patients (De Spiegelaere et al., 2015). Due
to this drug having a hypersensitive reaction to patients that are HLA-B*5701
carriers, the FDA has recommended all providers pre-screen their patients before
prescribing this medication in the treatment of HIV patients (De Spiegelaere et al.,
2015).
In this scenario, the patient carries the HLA-B*5701 allele; therefore, they should
not be prescribed abacavir. The side effects of a patient receiving abacavir that test
positive for the HLA-B*5701 allele can be fatal (De Spiegelaere et al., 2015).
Additionally, they may exhibit symptoms that include a fever, rash, vomiting, and
shortness of breath (De Spiegelaere et al., 2015).
A patient is prescribed antiplatelet therapy (clopidogrel) following an acute
myocardial infarction (MI). Six months later, the patient suffers another acute
MI. The patient has been adherent to therapy and the nurse practitioner
, suspects that clopidrogel may have been ineffective. How might genetic
testing have been beneficial in this case?
For the last ten years, I have been working in the cardiac Cath Lab. Antiplatelet
therapy is a crucial aspect of positive patient outcomes. Plavix (clopidogrel) is an
antiplatelet drug that inhibits the ability of platelets from sticking together,
preventing clot formation. Plavix has been a gold standard for patients that receive
coronary interventions. If a patient has another cardiac event, we use P2Y12 blood
samples to determine if the patient is responsive to Plavix. When a patient is
resistant to Plavix, it generally means the CYP2C19 gene is nonfunctional (Moon
et.al., 2018). When the CYP2C19 gene is nonfunctional, it cannot convert Plavix to
its active form (Moon et.al., 2018).
In this scenario, pre-genetic testing could have determined if Plavix would have
been an effective Antiplatelet therapy for this patient. Unfortunately, patients that
have genetic variants of CYP2C19 have an increased risk for developing a major
cardiac event, stroke, and death (Moon et.al., 2018).
Identify 2 limitations of pharmacogenomics testing. Explain.
Two limitations of pharmacogenetics testing are the lack of genetic knowledge and
cost-effectiveness evidence (Krebs, & Milani, 2019). Many providers do not order
genetic testing for their patients due to a lack of understanding. Providers are not
aware of the amount of pharmacogenomic-guided medications that patients are
exposed to. One Vanderbilt study found that out of the 52,000 individuals that
were surveyed, 65% were exposed to pharmacogenomic-guided drugs (Krebs, &
Milani, 2019). Furthermore, the age of healthcare providers varies dramatically.
Those who graduated more than ten years ago had minimal training on genetic
testing (Krebs, & Milani, 2019). Additionally, due to increased discoveries and
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