title: A droplet digital PCR detection method for rare L1 insertions in tumors.
abstract: BACKGROUND
  The active human mobile element, long interspersed element 1 (L1) currently populates human genomes in excess of 500,000 copies per haploid genome. Through its mobility via a process called target primed reverse transcription (TPRT), L1 mobilization has resulted in over 100 de novo cases of human disease and has recently been associated with various cancer types. Large advances in high-throughput sequencing (HTS) technology have allowed for an increased understanding of the role of L1 in human cancer; however, researchers are still limited by the ability to validate potentially rare L1 insertion events detected by HTS that may occur in only a small fraction of tumor cells. Additionally, HTS detection of rare events varies greatly as a function of read depth, and new tools for de novo element discovery are needed to fill in gaps created by HTS.
  
  
  RESULTS
  We have employed droplet digital PCR (ddPCR) to detect rare L1 loci in mosaic human genomes. Our assay allows for the detection of L1 insertions as rare as one cell in every 10,000.
  
  
  CONCLUSIONS
  ddPCR represents a robust method to be used alongside HTS techniques for detecting, validating and quantitating rare L1 insertion events in tumors and other tissues.
authors.affiliation: Tulane Cancer Center, 1430 Tulane Avenue, New Orleans, LA 70112 USA.
authors.forename: Travis B
authors.initials: TB
authors.lastname: White
authors.affiliation: Bio-Rad Laboratories, 750 Alfred Nobel Drive, Hercules, CA 94547 USA.|Present Address: Eureka Genomics, 2000 Alfred Nobel Drive, Hercules, CA 94547 USA.
authors.forename: Adam M
authors.initials: AM
authors.lastname: McCoy
authors.affiliation: Tulane Cancer Center, 1430 Tulane Avenue, New Orleans, LA 70112 USA.|Present Address: Division of Infectious Diseases, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115 USA.
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Streva
authors.affiliation: Bio-Rad Laboratories, 750 Alfred Nobel Drive, Hercules, CA 94547 USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Fenrich
authors.affiliation: Tulane Cancer Center, 1430 Tulane Avenue, New Orleans, LA 70112 USA.
authors.forename: Prescott L
authors.initials: PL
authors.lastname: Deininger
keywords: L1; droplet digital PCR; retrotransposon; tumor