Effect of Preservation on DNA and its Profiling from Sternum Bone from Unidentified Bodies

There are certain chemicals which are used to preserve the unknown human body parts, taken for identification via DNA analysis. Formalin is a common preservative which is used either in the case of an aborted fetus or other skeletal remains but such exhibits do not remain suitable for further DNA examination. Degradation of tissues leads to the concatenation of events which ultimately results in reduced DNA quantity. Quantitation of DNA plays an important role in the analysis of forensic samples like bone, tissues or any other biological material so that optimum quantity of extracted DNA would be taken for amplification and profiling. Stochastic effects are common to the PCR if the DNA quantity varies from the limit as in the case of excess DNA. Alleles were found off ladder whereas allele dropout occurs due to less DNA quantity. Generally, two types of sternum bones are received in the Forensic lab in missing identity cases, one wet bone with tissues attached to bone and preserved in nonporous container while another type is, wrapped in gauze/cloth and kept in an envelope to let it dry in normal environmental condition. A comparative data of 30 such sterna had been prepared from the samples examined in the laboratory after 3 to 4 years of sample collection. The result of this study showed the way, Sternum bone was taken and preserved for identification, may affect the quantity and quality of DNA and its profiling. The dry sternum bone gave better quantity of DNA and complete DNA profiling comparative to wet sternum kept in a plastic container. The wet sternum gave multiple peaks on small size markers and allele drops out on big size markers.