Quantitative and qualitative study of STR DNA from ethanol and formalin fixed tissues

Complete and concordant autosomal short tandem repeat (STR) DNA profiles were obtained from 2.0mg human tissue samples of various types after they were preserved for 24 weeks in 100% ethanol and amplified with the GlobalFiler(®) and the PowerPlex(®) Fusion Amplification Kits. When 4.0mg of the same tissues were preserved for 12 weeks in 10% Neutral Buffered Formalin (NBF) they yielded partial profiles when amplified with the same kits. However, these NBF preserved tissues yielded complete autosomal profiles when amplified with the AmpFlSTR(®) MiniFiler™ Amplification Kit. Six tissue specimens from the male donor were also amplified with the PowerPlex(®) Y-23 System. Y-STR profiles were successfully generated from 2.0mg tissue specimens when preserved for 12 weeks in 100% Ethanol. Only partial profiles were obtained when the fixation time was increased to 24 weeks. Only partial Y-STR profiles were also obtained from 4.0mg tissue specimen from the same donor when preserved in 10% NBF. In an attempt to optimize the method, the preserved samples that yielded partial profiles were homogenized using the BioMasher III disposable homogenizer and BioMasher III homogenizer and filter. These homogenized tissues did not yield significantly better or more complete profiles when using the GlobalFiler(®), AmpFlSTR(®) MiniFiler™ Amplification Kits, the PowerPlex(®) Fusion System or the PowerPlex(®) Y23 System. A total number of 240 tissue samples were analyzed in this project. The amplification of the tissues preserved in 10% NBF with kits such as AmpFlSTR(®) MiniFiler™ and GlobalFiler(®) Amplification Kits that contain mini STR primers can be beneficial in forensic testing. The results of the study indicate that in cases such as when a victim or a suspect is missing, the profiles obtained from minute amounts of chemically fixed tissues can be used as reference samples and compared to evidence found at the crime scene.