title: A case-control study of peripheral blood mitochondrial DNA copy number and risk of renal cell carcinoma.
abstract: BACKGROUND
  Low mitochondrial DNA (mtDNA) copy number is a common feature of renal cell carcinoma (RCC), and may influence tumor development. Results from a recent case-control study suggest that low mtDNA copy number in peripheral blood may be a marker for increased RCC risk. In an attempt to replicate that finding, we measured mtDNA copy number in peripheral blood DNA from a U.S. population-based case-control study of RCC.
  
  
  RESULTS
  Relative mtDNA copy number was measured in triplicate by a quantitative real-time PCR assay using DNA extracted from peripheral whole blood. Cases (n = 603) had significantly lower mtDNA copy number than controls (n = 603; medians 0.85, 0.91 respectively; P = 0.0001). In multiple logistic regression analyses, the lowest quartile of mtDNA copy number was associated with a 60% increase in RCC risk relative to the highest quartile (OR = 1.6, 95% CI = 1.1-2.2; P(trend) = 0.009). This association remained in analyses restricted to cases treated by surgery alone (OR (Q1) = 1.4, 95% CI = 1.0-2.1) and to localized tumors (2.0, 1.3-2.8).
  
  
  CONCLUSIONS
  Our findings from this investigation, to our knowledge the largest of its kind, offer important confirmatory evidence that low mtDNA copy number is associated with increased RCC risk. Additional research is needed to assess whether the association is replicable in prospective studies.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America. purduem@mail.nih.gov
authors.forename: Mark P
authors.initials: MP
authors.lastname: Purdue
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Hofmann
authors.forename: Joanne S
authors.initials: JS
authors.lastname: Colt
authors.forename: Mirjam
authors.initials: M
authors.lastname: Hoxha
authors.forename: Julie J
authors.initials: JJ
authors.lastname: Ruterbusch
authors.forename: Faith G
authors.initials: FG
authors.lastname: Davis
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Rothman
authors.forename: Sholom
authors.initials: S
authors.lastname: Wacholder
authors.forename: Kendra L
authors.initials: KL
authors.lastname: Schwartz
authors.forename: Andrea
authors.initials: A
authors.lastname: Baccarelli
authors.forename: Wong-Ho
authors.initials: WH
authors.lastname: Chow
mesh_terms: D000368:Aged; D002292:Carcinoma, Renal Cell / Q000453:epidemiology* / Q000235:genetics*; D016022:Case-Control Studies; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D060888:Real-Time Polymerase Chain Reaction; D012307:Risk Factors
chemical_list: D004272:DNA, Mitochondrial