NCJ Number
193737
Journal
Journal of Forensic Sciences Volume: 47 Issue: 1 Dated: January 2002 Pages: 175-177
Date Published
2002
Length
3 pages
Annotation
This paper used an alternative DNA extraction procedure from fingernail clippings. In addition, the application of an STR locus residing on the Y chromosome DYS19 was typed allowing for genetic characterization of the perpetrator.
Abstract
In the commission of a sexual assault or homicide, the victim may try to defend herself. In these cases, fingernail clippings from the victim are sent to the forensic laboratory for DNA extraction. Sometimes, with the current autosomal STR loci, the victim’s profile may mask the perpetrator’s DNA profile or the perpetrator’s DNA may be substantially lower in quantity than the victim’s DNA. Under these conditions, no characterization is possible. In this work, an alternative DNA extraction procedure for fingernail clippings after scratching was optimized. Eleven pairs of female volunteers scratched known male volunteers at which time one of four fingernails were clipped and preserved for DNA analysis. The nail clippings received no treatment before extraction. DNA samples were amplified and typed for DYS19 locus. The amplification product was evaluated in 2 percent agarose gels. PCR products were separated on 0.4 mm 6 percent denaturing polyacrylamide gels. Products were visualized using the silver stain method. The advantages of this method include: (1) the use of a nonorganic extraction technique that reduces purification-concentration time to 5 minutes; and (2) the specific analysis of DYS19 marker allows the detection of the perpetrator’s profile without potential confusion of the female’s profile. The results represent the data for locus DYS19 typing from fingernail clippings from the volunteers. In cases of male perpetrator and female victim the success rate of typing the suspect’s profile was variable, ascending to 100 percent if there is sufficient DNA recovered from the nail material. There was a good correlation between the success ratio and the total DNA concentration and/or DNA used for amplification. In conclusion, the application of this method and the typing of more Y-STR markers may allow more definitive characterization of the perpetrator on victims’ fingernail clippings, particularly in the situations where the perpetrator’s contribution may be too small or may be masked by the profile of the victim. Table, references