Citation

Klein SB, Buoncristiani MR. Forensic Sci. Int. Genet. 2017; 29: 109-117.

Affiliation

State of California, Department of Justice, Jan Bashinski DNA Laboratory, 1001 W. Cutting Blvd., Richmond, CA 94804, USA.

Copyright

(Copyright © 2017, Elsevier Publishing)

DOI

10.1016/j.fsigen.2017.03.021

PMID

28419902

Abstract

Analysis of sexual assault evidence, often a mixture of spermatozoa and victim epithelial cells, represents a significant portion of a forensic DNA laboratory's case load. Successful genotyping of sperm DNA from these mixed cell samples, particularly with low amounts of sperm, depends on maximizing sperm DNA recovery and minimizing non-sperm DNA carryover. For evaluating the efficacy of the differential extraction, we present a method which uses a Separation Potential Ratio (SPRED) to consider both sperm DNA recovery and non-sperm DNA removal as variables for determining separation efficiency. In addition, we describe how the ratio of male-to-female DNA in the sperm fraction may be estimated by using the SPRED of the differential extraction method in conjunction with the estimated ratio of male-to-female DNA initially present on the mixed swab. This approach may be useful for evaluating or modifying differential extraction methods, as we demonstrate by comparing experimental results obtained from the traditional differential extraction and the Erase Sperm Isolation Kit (PTC(©)) procedures.

Copyright © 2017 Elsevier B.V. All rights reserved.

Language: en

Keywords

Differential extraction; Non-sperm DNA carryover; Sexual assault evidence; Short tandem repeat; Sperm DNA recovery