title: Stability of cell-free DNA from maternal plasma isolated following a single centrifugation step.
abstract: OBJECTIVE
  Cell-free fetal DNA can be used for prenatal testing with no procedure-related risk to the fetus. However, yield of fetal DNA is low compared with maternal cell-free DNA fragments, resulting in technical challenges for some downstream applications. To maximize the fetal fraction, careful blood processing procedures are essential. We demonstrate that fetal fraction can be preserved using a single centrifugation step followed by postage of plasma to the laboratory for further processing.
  
  
  METHODS
  Digital PCR was used to quantify copies of total, maternal, and fetal DNA present in single-spun plasma at time points over a two-week period, compared with immediately processed double-spun plasma, with storage at room temperature, 4°C, and -80°C representing different postage scenarios.
  
  
  RESULTS
  There was no significant change in total, maternal, or fetal DNA copy numbers when single-spun plasma samples were stored for up to 1 week at room temperature and 2 weeks at -80°C compared with plasma processed within 4 h. Following storage at 4°C no change in composition of cell-free DNA was observed.
  
  
  CONCLUSIONS
  Single-spun plasma can be transported at room temperature if the journey is expected to take one week or less; shipping on dry ice is preferable for longer journeys.
authors: Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors: Angela N
authors: AN
authors: Barrett
authors: Henna A
authors: HA
authors: Thadani
authors: Cecille
authors: C
authors: Laureano-Asibal
authors: Sukumar
authors: S
authors: Ponnusamy
authors: Mahesh
authors: M
authors: Choolani
mesh_terms: D002498:Centrifugation; D004247:DNA / Q000097:blood / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D011296:Prenatal Diagnosis; D013048:Specimen Handling; D013696:Temperature
chemical_list: D004247:DNA