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Authors

  1. Samai, Kathryn PharmD, BCPS

Article Content

In recent years, there has been an increase in information regarding personalized medicine and pharmacogenomics. Personalized medicine is the tailoring of medical treatment based on individual characteristics often determined through genetic testing (FDA, 2013). Furthermore, pharmacogenomics specifically describes this practice in relation to medication selection, dosing, efficacy, and toxicity. Most health care professionals in the emergency and trauma setting may acknowledge that urgency takes precedent over the luxury of genetic testing. However, as evidence gathers and personalized medicine becomes more routine in practice, we need to think about the impact this information may have on our trauma patients.

 

There are many genetic targets already under investigation to improve the outcomes in trauma care, particularly on traumatic brain injury (TBI). A recent study reviewed a gene for ATP-binding cassette transporters (ABCC1) responsible for proteins involved in the movement of medications across membranes, including the blood-brain barrier. The study found an increased expression of these transporter proteins after TBI. Some medications affected by increased expression of ABCC1 include analgesics and antiepileptic drugs (Cousar et al., 2013). ABCC1 may play an important role in medication selection and dosing after TBI (Willyerd et al., 2015).

 

Ankyrin repeat and kinase domain containing 1 (ANKK1) is a gene that encodes for a protein kinase involved in the regulation of other genes downstream and may influence expression of neurotransmitters. When studied in TBI, ANKK1 was found to have a negative association with long-term cognitive performance after TBI (Yue et al., 2015). Additionally, apolipoprotein E (ApoE) has several alleles that have been studied in relation to Alzheimer's and elevated cholesterol. Conversely, the ApoE4 allele appears to play a role in neuroinflammatory pathways and has been associated with poor long-term outcomes at six months after TBI (Zhou et al., 2008). Interestingly, the identification of ApoE4's role in central nervous system inflammation may identify a target to develop a drug for TBI patients in the future.

 

ApoE4 has several other clinical implications in addition to TBI and illustrates the important consideration of ethical concern for genetic testing. Are our patients prepared to know the ancillary or unintentional information that may be discovered? There may be consequences to how a patient may deal with looming information about the potential to develop a disease as debilitating as Alzheimer's. It is also a complicated discussion to consider when a patient and caregiver are already dealing with recovery from TBI. Informed consent and discussion around genetic testing are crucial areas that may be difficult in emergency settings but could potentially provide family and caregivers information to help them accept long-term decisions. Although ethics have much to be determined, it is still remarkable to witness the extent in which personalized medicine is being studied in the trauma setting. Genetic research has not been solely limited to targets concerning TBI but also identification of targets that may impact severe complications in critically ill trauma patients.

 

Glucose-6 phosphate dehydrogenase (G6PD) deficiency is a well-known enzyme deficiency worldwide that has been associated with intolerance to certain medications and foods. Patients exposed to fava beans or certain medications, including several antibiotics, experience severe hemolytic anemia. Recently, a study reviewed the association of G6PD deficiency to sepsis in African-American patients with high injury severity scores (>=16). Those G6PD-deficient patients studied were more likely to have sepsis and anemia after trauma compared with nondeficient patients (Spolarics et al., 2001).

 

ABO blood typing was also associated with an increased risk for serious complication. Acute respiratory distress syndrome was increased in white patients with ABO blood type A after major trauma or sepsis (Reilly et al., 2014). This is a particularly interesting target to watch, because blood typing is already a standard of care. If ABO blood type A could predict other important clinical outcomes, it could be extremely useful ancillary information.

 

For trauma, personalized medicine is still in its early stages. Most studies available identify associations of outcomes and are not yet predictive. As evidence continues to support personalized medicine, we may see these types of tests incorporated into practice and could be an interesting transformation in trauma medicine.

 

REFERENCES

 

Cousar J. l., Conley Y. P., Anthony Willyerd C. F., Sarnaik A. A., Puccio A. M., Okonkwo D. O., Clark R. S. B. (2013). Influence of ATP-binding cassette polymorphisms on neurological outcome after traumatic brain injury. Neurocritical Care, 19(2), 192-198. [Context Link]

 

Reilly J. P, Meyer N. J., Shashaty M. G. S., Feng R., Lanken P. N., Gallop R., Christie J. D. (2014). ABO blood type A is associated with increased risk of ARDS in Whites following both major trauma and severe sepsis. Chest, 145(4), 753-761. [Context Link]

 

Spolarics Z., Siddiqi M., Siegel J., Garcia Z. C., Stein D. S., Ong H., Deitch E. A. (2001). Increased incidence of sepsis and altered monocyte function in severely injured type A-glucose-6-phosphate dehydrogenase-deficient African American trauma patients. Critical Care Medicine, 29(4), 728-736. [Context Link]

 

U.S. Food and Drug Administration. (2013). Paving the Way for Personalized Medicine: FDA's Role in a New Era of Medical Product Development. http://www.fda.gov/downloads/ScienceResearch/SpecialTopics/PersonalizedMedicine/. Retrieved October 26, 2015. [Context Link]

 

Willyerd F., Empey P., Philbrick A., Ikonomovic M. D., Puccio A. M., Kochanek P. M., Clark R. S. (2015). Expression of ATP-binding cassette transporters B1 and C1 after severe traumatic brain injury in humans. Journal of Neurotrauma. doi:10.1089/neu.2015.3879 [Context Link]

 

Yue J., Pronger A., Ferguson A., Temkin N., Sharma S., Rosand J., Geoffrey T. M. (2015). Association of a common genetic variant within ANKK1 with six-month cognitive performance after traumatic brain injury. Neurogenetics, 16(3), 169-180. [Context Link]

 

Zhou W., Di X. U., Peng X., Zhang Q., Jianping J., Keith A. (2008). Meta-analysis of APOE4 allele and outcome after traumatic brain injury. Journal of Neurotrauma, 25(4), 279-290. [Context Link]