Department of Biochemistry, Microbiology & Biotechnology, Kenyatta University, Nairobi, Kenya.
Department of Genetics & Genome Biology, University of Leicester, Leicester, UK.
Forensic Sci Int Genet. 2021 Jul;53:102535. doi: 10.1016/j.fsigen.2021.102535. Epub 2021 May 19.
Kenya is a diverse and populous nation that employs DNA evidence in its criminal justice system, and therefore requires reliable information on autosomal STR allele frequency variation across the country and in its many ethnic groups. In order to provide reference data and to assess population structure, we analysed the 21 autosomal STRs in the GlobalFiler multiplex in a sample of 510 indigenous Kenyans representing the country's eight former provinces, 43 of its 47 counties, three main linguistic families and all 29 ethnic groups that each comprise >0.5% of the 2019 census population. The indigenous population originated from successive migrations of Cushitic, Nilotic and Bantu speaking groups who settled in regions that suited their distinctive sustenance lifestyles. Consequently, they now largely reside in a patchwork of communities with strong associations with particular counties and provinces and limited degrees of inter-group marriage, as shown by DNA donors' ancestry details. We found significant genetic differentiation between the three Nilotic language sub-families, with Western Nilotes (the Luo ethnic group) showing greater similarity to the Bantu than the Southern and Eastern Nilotes which themselves showed closer affinity to the Cushitic speakers. This concurs with previous genetic, linguistic and social studies. Comparisons with other African populations also showed that linguistic affiliation is a stronger factor than geography. This study revealed several rare off-ladder alleles whose structure was determined by Sanger sequencing. Among the unusual features that could affect profile interpretation were a deletion of Amelogenin Y but no other forensic marker (autosomal or Y-chromosomal), a triallelic pattern at TPOX and an extremely short SE33 allele falling within the expected size range of D7S820. Compared with the currently implemented Identifiler multiplex, Random Match Probabilities decreased from 6.4 × 10 to 3.9 × 10. The appreciation of local population structure provided by the geographically and ethnically representative sample in this study highlights the structured genetic landscape of Kenya.
肯尼亚是一个多样化和人口众多的国家，在其刑事司法系统中使用 DNA 证据，因此需要可靠的全国和各民族常染色体 STR 等位基因频率变化信息。为了提供参考数据并评估人口结构，我们分析了代表该国 8 个前省、47 个县、3 个主要语言家族和每个占 2019 年人口普查人口 0.5%以上的 29 个民族的 510 名肯尼亚本土人的 21 个常染色体 STR 基因座。这些本土人起源于库希特语、尼罗语和班图语群体的连续迁徙，他们在适合其独特生存方式的地区定居。因此，他们现在主要居住在与特定县和省有强烈联系的拼凑社区中，群体间通婚的程度有限，这一点从 DNA 供体的祖先细节中可以看出。我们发现三个尼罗语亚家族之间存在显著的遗传分化，西部尼罗人（卢奥族）与班图人比与南部和东部尼罗人更为相似，而后者与库希特语使用者更为相似。这与之前的遗传、语言和社会研究一致。与其他非洲人群的比较也表明，语言联系比地理位置更重要。本研究还发现了几个罕见的偏离梯级等位基因，其结构通过 Sanger 测序确定。在可能影响图谱解释的异常特征中，有 Y 染色体缺失的 amelogenin Y 但没有其他法医标记（常染色体或 Y 染色体），TPOX 的三等位基因模式以及属于 D7S820 预期大小范围内的非常短的 SE33 等位基因。与目前实施的 Identifiler 多重扩增试剂盒相比，随机匹配概率从 6.4×10 降至 3.9×10。本研究中具有地理和民族代表性的样本对当地人口结构的评估突出了肯尼亚结构化的遗传景观。
