A case of a differential lysis for male infidelity

The wife became suspicious about a continued stains in her husbands underwear which appeared to be from encounters at his office.  After many discussions she sent in a pair that she was confident would produce female DNA from intercourse or fellatio.  Because she had handled the sample she also sent her control swab to ensure her contamination was not present.

DNA from epithelial cells can be removed using a procedure called a differential lysis, which takes advantage of unique properties associated with each cell type. The cells are removed from the suspected material by soaking them in a gentle solution.  Epithelial cell DNA (such as those found in vaginal fluid) is isolated under mild conditions that break open the epithelial cells but leave the sperm cells DNA intact.  The DNA in spermatozoa can then be extracted using a more harsh extraction procedure.

The DNA profile proved that there was only one male profile in her husbands underwear.  Since the profile was not complete and the Epithelial cell DNA matched the sperm DNA, it was concluded that the sample was most likely not from ejaculate matter because her husband was not vasectomized.   Had the sample been from sperm cells, the profile R1 should have been complete (unless badly degraded with lysed cells).  Therefore the two conclusions (no female profile and no ejaculate matter) cleared him of wrong doing.

Case # FR2005607 (GQ0017542) 

Evidence 

The items to be tested are R1- 1.7ml tube containing white micropunches labeled as “GQ0017542 DL”.  R2- 4 buccal swabs labeled as “Customer”. 

Analysis 

A differential lysis was performed to separate sperm and epithelial cells in different groups allowing a profile for any contributors to the stain to be profiled, followed by DNA extraction, PCR and Genotyper 

Results:
DNA ANALYSIS RESULTS: Allele and number of repeats

 *Partial profile 

Conclusions: 

Based on the analysis of the alleles CSF1PO, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, FGA, THO1, TPOX, vWA, Penta E, Penta D and Amelogenin the profile obtained from Sample R1 is consistent with one contributor and the Female Enriched Cell Fraction is a slight carry over from the Male Cell Fraction. The contributor of Sample R1 is a male profile and a profile consistent with female DNA was not detected.  The profile from Sample R2 is excluded as being a contributor to the stain. 

* Minor peaks were present and cannot be read with 100% confidence due to laboratory’s threshold level.