Evaluating a Test for Shedding Propensity Using Tape Lifts from Different Skin Locations

Author

Xiao M. Chen, CUNY John Jay CollegeFollow

Date of Award

Fall 12-27-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department/Program

Forensic Science

Language

English

First Advisor or Mentor

Mechthild Prinz

Second Reader

Nicholas Dominick Koslap Petraeo

Third Advisor

Grace Axler-DiPerte

Abstract

The shedding propensity of a person can assist data interpretation in casework when assessing the possibility of passive transfer for DNA analysis. Past studies on shedding propensity evaluated palmar skin (washed and unwashed) deposits. This study compared different skin locations with respect to shedding propensity, and explored the potential of tape-lifts as a skin surface collection method. Eight different skin types and samples were collected with adhesive tape disks from 28 participants over three non-consecutive days; the washed and unwashed fingers from both hands, toe, and arm, neck below ear, and nape. Samples were extracted, quantified, amplified, genotyped, and evaluated for the presence of DNA mixtures. Concentration for DNA mixtures were then modified by subtracting the non-donor DNA percentage. DNA concentrations for different skin sample types were log-transformed and tested for Pearson r correlation values. Of all the sampling locations tested, left and right washed fingers were the most suitable to predict shedding propensity. Despite lower DNA concentrations than for sebaceous and unwashed finger samples, washed fingers were the most consistent over the three collections, and provided good shedding propensity division within donors. A preliminary model was made to predict shedding propensity. Only for left washed fingers of “high shedders” the prediction for an individual remained unchanged over all three weeks, while for other locations and “medium” and “low” shedders predictions were inconsistent. Tape lifts from washed fingers seem to be a possible tool to determine shedding propensity, and further work will be needed on sampling other areas.

Recommended Citation

Chen, Xiao M., "Evaluating a Test for Shedding Propensity Using Tape Lifts from Different Skin Locations" (2021). CUNY Academic Works.
https://academicworks.cuny.edu/jj_etds/199