This study presents a large-scale sampling of DNA from telogen hairs in order to determine the amount that can be extracted, and a method for assessing the degradation level of DNA from telogen hairs is also presented, as well as the effect of degradation on genotyping.
The study found that very low concentrations of DNA could be extracted from shed telogen hairs of consistent length; and the amount extracted varied from person to person. Most samples yielded a quantity of 550 pg or less per hair. Samples of epithelial DNA present on telogen hairs produced the same type as the hair donor, and the amount varied significantly. DNA from telogen hairs showed a high level of degradation, and this degradation reduced the probability of obtaining a full DNA profile. Based on these results, if sufficient DNA can be recovered from hair (>60 pg), partial profiles may be produced when using the Miniplex short tandem repeat (STR) systems. For larger amounts of DNA (>550 pg), more loci can be obtained; however, full profiles are rarely recovered due to the extensive degradation present. In addition to degradation, inhibition was found to be a problem for some samples. Telogen hairs can be an important form of forensic evidence, both for morphological and DNA studies. Since the amount of nuclear DNA that can be extracted may be very low as well as highly degraded, however, for many samples, mtDNA analysis may provide a better chance of obtaining a profile. For this study, nuclear DNA was extracted from human telogen hairs of 60 individuals. Six to nine hairs from each individual were individually extracted. A selective extraction buffer was used to remove epithelial cell DNA, and the amount of exogenous DNA was determined. 3 tables, 5 figures, and 16 references