Morphological study of fragmented DNA on touched objects

Received 26 October 2007; received in revised form 1 September 2008; accepted 2 September 2008. published online 13 October 2008.

Abstract

In recent years, forensic scientists showed that an individual’s genetic profile can be retrieved from touched objects. Degraded DNA is believed to originate from epidermal cells and to be responsible for this phenomenon, yet the mechanism has not been confirmed. In the present study, we carried out a morphological and immunohistochemical investigation of nuclear DNA in differentiating keratinocytes in the skin and also a genetic analysis of DNA on swabs of human skin. Immunoelectron microscope analysis showed that single-stranded DNA was found both in the cornified layer of the skin and in swabs. Real-time-PCR assay proved that the DNA in the swabs was derived from the human DNA. Electron microscopic analysis of shadow-cast showed the presence of small DNA fragments in the swabs. It is conceivable that these DNA fragments on touched objects may originate from the epidermal cells of the cornified layer that are constantly sloughed off and leave for skin surface with sweat.

Keywords: Touch DNA, Genetic profile, DNA fragment, Nuclear DNA, Skin, Keratinization

a Department of Forensic Medicine, School of Medicine, University of Occupational and Environmental Health Yahata Nishi-ku, Kitakyushu, 807-8555 Japan

b Forensic Science Laboratory, Fukuoka Prefectural Police Headquarters, Higashikouen 7-7, Hakataku, Fukuoka City, Fukuoka 812-8576, Japan

c Bio-information Research Center, University of Occupational and Environmental Health, Yahata Nishi-ku, Kitakyushu 807-8555, Japan

Corresponding author. Tel.: +81 93 691 7432; fax: +81 93 601 6257.

PII: S1872-4973(08)00133-6

doi:10.1016/j.fsigen.2008.09.002

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