Study of DNA Transfer from Hand Exfoliated Cells with Non-permeable Carriers
10.13471/j.cnki.j.sun.yat-sen.univ（med.sci）.20240907.012
- VernacularTitle:非渗透性载体手部脱落细胞DNA转移研究
- Author:
Li YUAN
1
;
Kainan ZOU
1
;
Shicheng HAO
2
;
Haixiao DENG
2
;
Jinpei ZHANG
2
;
Libin WU
2
;
Hang HE
2
Author Information
1. Shanghai Key Laboratory of Scene Evidence， Shanghai Research Institute of Criminal Science and Technology， Shanghai 200083， China
2. Key Laboratory of Evidence Science of Ministry of Education， China University of Political Science and Law， Beijing 100088， China
- Publication Type:Journal Article
- Keywords:
forensic biological evidence;
exfoliated cells;
DNA transfer;
non-porous substrates;
activity level;
vehicles
- From:
Journal of Sun Yat-sen University(Medical Sciences)
2024;45(5):818-825
- CountryChina
- Language:Chinese
-
Abstract:
ObjectiveTo investigate primary and secondary transfer of exfoliated cells from human hands on non-porous substrates such as plastic steering wheel or computer mouse. MethodsDNA detection sensitivity and detection limit for mixed DNA profiling were examined to understand our laboratory’s ability to test for trace DNA. Forensic swabs were used to collect samples from volunteers’ one-hour-long unwashed hands， substrates touched by volunteers’ dominant hand 30 min after hand washing， substrates touched by volunteers 30 min after washing their hands and then immediately or 30 min following shaking hands， and individual A’s daily-use substrates touched by individual B and then by individual A again. Simulations were conducted to assess the potential for introduction of another person’s exfoliated cells from hands into routine casework samples. ResultsOur laboratory can obtain a full DNA profile from as little as 0.020 ng of DNA and detect minor components in a 1：9 mixed DNA sample. 85% of samples from unwashed hands yielded a full DNA profile. Primary transfer of a full DNA profile was found in 77% of substrates touched by volunteers’ dominant hand 30 min after hand washing， allowing differentiation between good and poor shedders， with no significant difference in genders and substrate types. 75% of substrates touched 30 min after hand washing and then immediately following handshaking yielded the other individual’s DNA profile （secondary transfer）， with the number of short tandem repeat （STR） loci detected ranging from 0 to 23； the percentage and number decreased substantially when the substrates were touched 30 minutes later. No foreign DNA was detected in routine casework samples with introduced exfoliated cells from hands. When two individuals took turns touching items with their hands， the major contributor to the DNA profile was not always the individual who made the last contact. ConclusionsPrimary and secondary DNA transfer can be detected on non-porous substrates， and based on the deposit of hand exfoliated cells， individuals can be categorized as good or poor shedders， which is an important factor affecting detection of DNA transfer. Besides considering the laboratory’s DNA detection sensitivity， if DNA is detected on substrates by hand contact， we need to take into account the potential for secondary transfer at different levels of activity when interpreting the results.
