If every cloud has a silver lining, does every gene in our body also have a specific benefit?
Three years ago, researchers at Duke University Medical Center discovered that patients with the E-4 variant of the apolipoprotein gene suffered greater cognitive declines after heart bypass surgery then patients without this gene variant. This APO gene is also associated with some common forms of Alzheimer's disease.
But in a new study published in the August edition of the journal Anesthesiology, a team of Medical Center researchers discovered that the E-4 gene variant can also help protect kidneys from injury during heart surgery, making for an interesting paradox.
Assistant Professor of Anesthesiology Dr. Mark Stafford-Smit, the lead author of the study, explained that this is not only the first case of a proven genetic basis for kidney impairment but also a curious phenomenon. "While the gene is the devil in case of Alzheimer's disease, it's the hero with the kidneys," he said.
Out of approximately 800,000 patients who undergo coronary bypass surgery each year, about eight percent suffer some form of kidney dysfunction. In one percent of cases, the injury to the kidney is serious enough to require a dialysis machine.
Researchers are not sure why kidneys might be damaged during the surgery. Still, regardless of the seriousness or cause of the injury, Stafford-Smit pointed out that these dysfunctions in the renal system cause significant increases in patient morbidity, mortality and overall cost of the procedure.
"Kidney injury [during heart surgery] isn't frequent but if it is severe it greatly increases the chance that the patient won't survive," Stafford-Smit said.
The researchers took patients' blood samples and tested them for accumulated levels of creatinine, a product of the body's daily functions that is usually filtered out of the blood by the kidneys. Since increased levels of creatinine in the patient's blood are accompanied by other harmful chemicals, it is a clear indicator of kidney dysfunction.
Associate Professor of Anesthesiology Dr. Mark Newman explained that this latest finding would enable doctors to better tailor specific operations to the patient's genotype. "Down the road it may help us to understand which patients are at a greater risk for a specific type of procedure," he said.
Stafford-Smit agreed, further explaining that genetic factors could potentially determine what type of surgery the patient would have or if it would be better to rely on medication alone.
Newman added that further identification of risks associated with certain genes brings researchers closer to finding out the exact causes of kidney injury during heart surgery.
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