From One Strand Dyed/Undyed Hair With/Without Root to Fast and Successful STR Profiling and Evaluation With Principle Component Analysis.

Abstract

Fallen/shed single hair shafts with/without roots can be encountered as evidence in crime scenes. Identification from hair exhibits serious difficulties, due to the low amount of DNA, PCR inhibitors, and the existence of DNA mostly in degraded forms. Exposure of hair to chemical oxidation, sunlight, etc. brings extra difficulties to DNA analysis. In single hair shafts, no satisfactory nuDNA test method that can be used both for dyed/undyed single hair shafts with/without root exists in the literature. Next-generation systems are expensive, have a labor-intensive workflow, and are not available in many forensic laboratories. Here an STR profiling method has been developed modifying an isolation kit method for an easy, successful DNA for (1) dyed/undyed single hairs with root and (2) without root from 36 individuals and compared with the unmodified method (total 432 analyzed samples). Modified silica-based isolation method, yielded 0.65-1.05 ng/µL DNA. The success of STR typing after capillary electrophoresis was 96%-98% for dyed/undyed hair with roots and 89%-93% for rootless ones, while the results for the unmodified method were 67%-82%. The results were investigated using PCA, t-test, and F-test. This protocol is simple, inexpensive, does not require automation, and can be performed using kits/equipment available in every forensic laboratory for forensic genotyping.