Effect of Storage Time on DNA Obtained from Umbilical Cord Used in Forensic Identification.

Abstract

Background/objectives: In the identification of human remains, their genetic profile can be compared with that obtained from biological samples of the person from whom they are suspected to have come. Our aim was to evaluate the effect of storage time on DNA obtained from umbilical cord that could be used as a reference in forensic identification.

Methods: Fifteen umbilical cords stored by the donors in their homes for a period of between 0.5 and 47 years were collected. Saliva samples were obtained for use as a reference. DNA extraction was performed using the PrepFiler Express BTA™ Forensic DNA Extraction Kit and quantified using the Quantifiler™ HP DNA quantification kit. STR profiling was performed using the GlobalFiler™ PCR Amplification Kit. Alleles were detected using an ABI PRISM^® 3500 genetic analyzer.

Results: In samples from 0.5 to 21 years of age, DNA concentration and degradation index (DI) did not follow a linear pattern over time; the genetic profiles obtained matched that of the corresponding saliva sample. Older samples showed lower DNA concentration values and higher DIs. The percentage of alleles recovered decreased to 31% in the oldest umbilical cord analyzed. However, from a sample stored for 31 years, a DNA concentration and DI similar to the younger samples were obtained, along with a complete STR profile.

Conclusions: It is possible to obtain STR profiles useful for forensic identification from umbilical cords even after decades of storage; however, success is highly variable and cannot be predicted from storage time alone.