Aug. 1, 2008 Genetic factors were shown to influence the number of copies of mitochondrial DNA (mtDNA) in healthy cells. A lower mtDNA copy number was associated with an increased risk of renal cell cancer in a case-control study, researchers report in the July 29 online issue of the Journal of the National Cancer Institute.
The degree to which mtDNA copy number is controlled genetically has been unknown. Previous studies have suggested that low mtDNA copy number may be associated with an increased risk of a variety of cancers, but researchers have not explored its possible association with kidney cancer.
In the first portion of the study, Xifeng Wu, M.D., Ph.D., of the University of Texas M. D. Anderson Cancer Center in Houston and colleagues analyzed mtDNA copy number from the peripheral blood cells of more than 300 identical and non-identical twins to estimate the influence of genetics on copy number. In the second portion of the study, the researchers analyzed mtDNA copy number from 260 renal cell cancer patients and 281 control subjects to examine the association between copy number and renal cancer risk.
The investigators estimate that genetics accounts for 65 percent of the variation in mtDNA copy number in the population. On average, renal cancer patients had a lower mtDNA copy number in peripheral blood cells than did control subjects. They also observed a statistically significant trend for increased risk of renal cell cancer with decreasing mtDNA copy number.
"To the best of our knowledge, this is the first molecular epidemiological study to evaluate mtDNA content in lymphocytes as a susceptibility biomarker for cancer," the authors write.
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