Aalbers Sanne E, Gettings Katherine B
Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20740, USA; US National Institute of Standards and Technology, Biomolecular Measurement Division, 100 Bureau Drive, Gaithersburg, MD 20899, USA.
US National Institute of Standards and Technology, Biomolecular Measurement Division, 100 Bureau Drive, Gaithersburg, MD 20899, USA.
Forensic Sci Int Genet. 2025 Aug 5;80:103336. doi: 10.1016/j.fsigen.2025.103336.
Population databases allow us to attach probabilities to DNA evidence by the estimation of genotype frequencies, which rely on accurate allele frequency estimates. As short tandem repeat (STR) marker sets for human identification have expanded to include more discriminating markers, and especially now that sequencing techniques allow us to distinguish between alleles based on variation in underlying base-pair structure, it is important to reevaluate existing guidance on population database sizes for the estimation of allele frequencies. In this paper, we revisit the topic of population sampling by focusing on the representation of alleles, i.e. whether alleles are observed or not, in a sample of individuals containing data for highly polymorphic autosomal STR loci. The effect of both length- and sequence-based STR data on population sample size implications are demonstrated, and differences between lesser and more polymorphic markers are discussed. The consequences of using a limited number of individuals are explored and the impact of increasing population sample sizes by combining different data sets is shown to help determine the point at which further sampling may no longer provide significant value. Finally, different approaches for accommodating previously unobserved alleles and their impact on DNA evidence evaluations are discussed.
群体数据库使我们能够通过估计基因型频率来为DNA证据赋予概率，而基因型频率的估计依赖于准确的等位基因频率估计。随着用于人类身份识别的短串联重复序列（STR）标记集不断扩展，纳入了更多具有鉴别力的标记，特别是现在测序技术使我们能够根据潜在碱基对结构的差异区分等位基因，重新评估现有关于群体数据库大小以估计等位基因频率的指导意见变得很重要。在本文中，我们通过关注在包含高度多态性常染色体STR位点数据的个体样本中等位基因的表现形式，即等位基因是否被观察到，来重新审视群体抽样的话题。展示了基于长度和序列的STR数据对群体样本大小的影响，并讨论了多态性较低和较高的标记之间的差异。探讨了使用有限数量个体的后果，并表明通过组合不同数据集增加群体样本大小的影响有助于确定进一步抽样可能不再提供显著价值的点。最后，讨论了容纳先前未观察到的等位基因的不同方法及其对DNA证据评估的影响。
