The Effect of Common Imaging and Maceration Techniques on DNA Recovery from Skeletal Remains

DNA testing is an essential tool for human identification, particularly from skeletal remains. Therefore it is important to understand how different processing methods used to clean and prepare bones for research and analysis influence the recoverability of CODIS marker DNA from skeletal remains. Thirteen elements from three sets of recently skeletonized remains were macerated with hot water, scanned by computed tomography (CT), X-rayed, or exposed to a combination of the three methods. The number of CODIS marker loci, relative fluorescent units (RFU) values and DNA yields were compared to an unprocessed control group to determine if there was a significant difference in STR-DNA recoverability between processed and unprocessed remains.

The RFU values differed significantly between the processed and unprocessed groups (p=0.000) and among samples from each separate processing treatment. CODIS-DNA yields showed a different pattern. None of the processing methods significantly affected yield. There was a significant difference in the profile completeness (number of loci) between the overall group of processed and unprocessed remains (p=0.007). However, results indicate no significant difference when comparing each method individually. Due to the inconsistencies between the different measures of DNA quality and quantity, it is still unclear how these three processing methods affect DNA recovery from skeletal remains.

Identifications are established by amplifying a standard set of CODIS marker loci comprising a “complete profile,” but complete profiles do not indicate an equal recovery of CODIS marker DNA between samples. It is only necessary for the quantity of CODIS marker DNA to exceed a minimum RFU threshold for a locus to be identified. Since processing skeletal remains appears to reduce RFU values, maintaining an unprocessed element from every skeleton would maximize CODIS marker preservation for future testing without significantly changing current processing procedures.