title: Single-cell forensic short tandem repeat typing within microfluidic droplets.
abstract: A short tandem repeat (STR) typing method is developed for forensic identification of individual cells. In our strategy, monodisperse 1.5 nL agarose-in-oil droplets are produced with a high frequency using a microfluidic droplet generator. Statistically dilute single cells, along with primer-functionalized microbeads, are randomly compartmentalized in the droplets. Massively parallel single-cell droplet polymerase chain reaction (PCR) is performed to transfer replicas of desired STR targets from the single-cell genomic DNA onto the coencapsulated microbeads. These DNA-conjugated beads are subsequently harvested and reamplified under statistically dilute conditions for conventional capillary electrophoresis (CE) STR fragment size analysis. The 9-plex STR profiles of single cells from both pure and mixed populations of GM09947 and GM09948 human lymphoid cells show that all alleles are correctly called and allelic drop-in/drop-out is not observed. The cell mixture study exhibits a good linear relationship between the observed and input cell ratios in the range of 1:1 to 10:1. Additionally, the STR profile of GM09947 cells could be deduced even in the presence of a high concentration of cell-free contaminating 9948 genomic DNA. Our method will be valuable for the STR analysis of samples containing mixtures of cells/DNA from multiple contributors and for low-concentration samples.
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: Tao
authors.initials: T
authors.lastname: Geng
authors.forename: Richard
authors.initials: R
authors.lastname: Novak
authors.forename: Richard A
authors.initials: RA
authors.lastname: Mathies
mesh_terms: D045744:Cell Line, Tumor; D005260:Female; D053803:Forensic Genetics / Q000379:methods*; D006801:Humans; D008297:Male; D044085:Microfluidics / Q000379:methods*; D018895:Microsatellite Repeats / Q000235:genetics*; D059010:Single-Cell Analysis / Q000379:methods*