title: Identification of sample donor by 24-plex short tandem repeat in a post-race equine plasma containing dexamethasone.
abstract: BACKGROUND
  Animal sport such as horseracing is tainted with drug abuse as are human sports. Treatment of racehorses on race day with therapeutic medications in most cases is banned, and thus, it is essential to monitor the illicit use of drugs in the racing horse to maintain integrity of racing, ensure fair competition and protect the health, safety and welfare of the horse, jockeys and drivers. In the event of a dispute over the identity of the sample donor, if the regulator can provide evidence that the DNA genotype profile of the post-race sample matched that of the alleged donor, then the potential drug violation case might be easily resolved without legal challenges.
  
  
  METHODS
  We present a case study of a racehorse sample that tested positive for dexamethasone in a post-race plasma sample in Pennsylvania (PA) but the result was challenged by the trainer of the horse. Dexamethasone is a synthetic glucocorticoid widely used in the management of musculoskeletal problems in horses but its presence in the horse during competition is banned by the PA Racing Commissions. The presence of dexamethasone in the post-competition plasma sample was confirmed using liquid chromatography-tandem mass spectrometry. However, this finding was challenged by the trainer of the horse alleging that the post-race sample was not collected from his/her horse and thus petitioned the Commission to be absolved of any wrong-doing. To resolve the dispute, a DNA test was ordered by the PA Racing Commission to identify the correct donor of the dexamethasone positive sample. For this purpose, a 24-plex short tandem repeat analysis to detect 21 equine markers and three human markers was employed. The results indicated that all the samples tested had identical DNA profiles and thus, it was concluded that the samples were collected from the same horse and that the probability of drawing a false conclusion was approximately zero (1.5 × 10(-15)).
  
  
  CONCLUSIONS
  The plasma sample confirmed for the presence of dexamethasone was collected from the alleged horse.
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, PA 19348 USA.
authors.forename: Jin-Wen
authors.initials: JW
authors.lastname: Chen
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, PA 19348 USA ; Pennsylvania Equine Toxicology & Research Center, Department of Chemistry, West Chester University, 220 E Rosedale Avenue, West Chester, PA 19382 USA.
authors.forename: Cornelius E
authors.initials: CE
authors.lastname: Uboh
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, PA 19348 USA.
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Soma
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, PA 19348 USA.
authors.forename: Youwen
authors.initials: Y
authors.lastname: You
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, PA 19348 USA.
authors.forename: Zibin
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, PA 19348 USA.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Li
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, PA 19348 USA.
authors.forename: Fuyu
authors.initials: F
authors.lastname: Guan
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, PA 19348 USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
keywords: Dexamethasone; Hair; Horse; Liquid chromatography tandem mass spectrometry; Plasma; Short tandem repeat; Urine