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Determining the number of contributors (NOC) accurately in a forensic DNA mixture profile can be challenging. To address this issue, there have been various studies that examined the uncertainty in estimating the NOC in a DNA mixture profile. However, the focus of these studies lies primarily on dominant populations residing within Europe and North America. Thus, there is limited representation of Asian populations in these studies. Further, the effects of allele dropout on the NOC estimation has not been explored. As such, this study assesses the uncertainty of NOC in simulated DNA mixture profiles of Chinese, Malay, and Indian populations, which are the predominant ethnic populations in Asia. The Caucasian ethnic population was also included to provide a basis of comparison with other similar studies. Our results showed that without considering allele dropout, the NOC from DNA mixture profiles derived from up to four contributors of the same ethnic population could be estimated with confidence in the Chinese, Malay, Indian and Caucasian populations. The same results can be observed on DNA mixture profiles originating from a combination of differing ethnic populations. The inclusion of an overall 30% allele dropout rate increased the probability (risk) of underestimating the NOC in a DNA mixture profile; even a 3-person DNA mixture profile has a > 99% risk of underestimating the NOC as two or fewer contributors. However, such risks could be mitigated when the highly polymorphic SE33 locus was included in the dataset. Lastly there was a negligible level of risk in misinterpreting the NOC in a mixture profile as deriving from a single source profile. In summary, our studies showcased novel results representative of the Chinese, Malay, and Indian ethnic populations when examining the uncertainty in NOC estimation in a DNA mixture profile. Our results would be useful in the estimation of NOC in a DNA mixture profile in the Asian context. [ABSTRACT FROM AUTHOR]

The extraction of DNA is a fairly standard procedure routinely undertaken in biological academic and research settings. In a forensic DNA context, DNA extraction is the crucial first step toward the generation of DNA profiles used to support convictions or exonerations in the criminal justice system. However, it is often complicated by the additional challenge of yielding sufficient quantities of clean DNA that is free from environmental inhibitors, from a wide spectrum of sample types which may contain limited quantities of biological material. While improvements in methods and technology over the decades have sped up and simplified the process of DNA extraction, several issues remain to be fully addressed—such as the incomplete separation of spermic DNA from sperm‐epithelial cell mixtures, increasing demands for ever‐faster DNA results, or even on‐scene DNA processing, and processing of difficult samples such as skeletal remains or samples contaminated by Chemical, Biological, or Radiological (CBR) agents. These challenges are often compounded by high work volumes and limited quantities of starting material. As such, this review focuses on recent trends and developments in four areas of forensic DNA extraction: (a) analysis of sexual assault evidence which often represents a significant portion of a forensic DNA laboratory's casework, (b) use of portable rapid DNA instruments which has gained much traction among law enforcement in recent times, (c) DNA extraction from difficult and CBR‐contaminated samples which, albeit rare, would be essential in a DNA laboratory's toolbox in the event of an incident, and (d) bypassing DNA extraction altogether. This article is categorized under:Forensic Biology > Forensic DNA Technologies [ABSTRACT FROM AUTHOR]