DNA analysis has revolutionised forensic science by enabling the identification of individuals from the trace amounts of DNA transferred at a crime scene.
An individual’s DNA can be transferred either within an intact cell - such as a blood cell, a skin cell or a sperm cell - or as free DNA.
We shed cells and DNA wherever we go, often in a context-specific manner: different types of contact will result in the transfer and mixture of different cell types.
While DNA analysis is widely applied in a forensic setting, identifying individuals becomes much more difficult when material from multiple individuals is mixed.
Around 45 per cent of forensic samples within the UK criminal justice system are believed to contain human DNA from two or more individuals.
If there is DNA from more than one person present in a sample, traditional techniques may not be able to separate the identities of all the contributing individuals and reduce the success of searches against DNA databases.
The SCAnDi Project
Single-cell genomic technologies have advanced rapidly in the last decade, with an array of approaches for the analysis of genetic material from individual cells, but these technologies have had limited exploration in a forensic setting.
These approaches could allow DNA profiles to be constructed from cells found at the scene of a crime. These profiles could also be linked with images of the cell, which could provide valuable contextual information to forensic experts - particularly where there are mixed samples.
Funded by the UKRI Economic and Social Research Council, the project - ‘Single-cell and single molecule analysis for DNA identification (SCAnDi)' - brings together multidisciplinary expertise, including single-cell genomics, DNA profiling, microfluidics, artificial intelligence, forensic genetics with practitioners in the justice system to deliver proof-of-principle research to demonstrate the applicability of single-cell analysis in forensic science.
