title: Reproducibility of Circulating MicroRNAs in Stored Plasma Samples.
abstract: BACKGROUND
  Most studies of microRNA (miRNA) and disease have examined tissue-specific expression in limited numbers of samples. The presence of circulating miRNAs in plasma samples provides the opportunity to examine prospective associations between miRNA expression and disease in initially healthy individuals. However, little data exist on the reproducibility of miRNAs in stored plasma.
  
  
  METHODS
  We used Real-Time PCR to measure 61 pre-selected microRNA candidates in stored plasma. Coefficients of variation (CVs) were used to assess inter-assay reliability (n = 15) and within-person stability over one year (n = 80). Intraclass correlation coefficients (ICCs) and polychoric correlation coefficients were used to assess within-person stability and delayed processing reproducibility (whole blood stored at 4°C for 0, 24 and 48 hours; n = 12 samples).
  
  
  RESULTS
  Of 61 selected miRNAs, 23 were detected in at least 50% of samples and had average CVs below 20% for inter-assay reproducibility and 31 for delayed processing reproducibility. Ten miRNAs were detected in at least 50% of samples, had average CVs below 20% and had ICCs above 0.4 for within-person stability over 1-2 years, six of which satisfied criteria for both interassay reproducibility and short-term within-person stability (miR-17-5p, -191-5p, -26a-5p, -27b-3p, -320a, and -375) and two all three types of reproducibility (miR-27b-3p and -26a-5p). However, many miRNAs with acceptable average CVs had high maximum CVs, most had low expression levels, and several had low ICCs with delayed processing.
  
  
  CONCLUSIONS
  About a tenth of miRNAs plausibly related to chronic disease were reliably detected in stored samples of healthy adults.
authors: Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America.
authors: Monica L
authors: ML
authors: Bertoia
authors: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America; Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America.
authors: Kimberly A
authors: KA
authors: Bertrand
authors: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America.
authors: Sherilyn J
authors: SJ
authors: Sawyer
authors: Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America; Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America; Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America.
authors: Eric B
authors: EB
authors: Rimm
authors: Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America; Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America.
authors: Kenneth J
authors: KJ
authors: Mukamal
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood*; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D003430:Cross-Sectional Studies; D005500:Follow-Up Studies; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000097:blood* / Q000235:genetics*; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results
chemical_list: D015415:Biomarkers; D035683:MicroRNAs