Systematic evaluations of forensic effectiveness and genetic structures of two ethnic groups in Northwest China using a self-developed Multi-InDel panel

Abstract Background The use of compound markers has gained significant interest among forensic practitioners, due to their ability to enhance genetic marker polymorphisms by introducing new alleles. Two or more closely linked insertion/deletion (InDel) markers form a compound marker termed Multi-InDel, which offers the advantages of microhaplotype (MH) and can be genotyped using capillary electrophoresis (CE) platform. A multiplex amplification panel, including 41 Multi-InDel markers and the sex-determination locus Amelogenin, was developed and validated as an effective tool for forensic and population genetics applications. Methods A total of 245 Kazakh and Kyrgyz samples from China were genotyped based on the 41 Multi-InDel markers to evaluate the forensic efficacy of the panel. In addition, Multi-InDel genotyping data from 28 reference populations were collected, and population genetic analyses were performed to elucidate the genetic backgrounds of Chinese Kazakh and Kyrgyz groups. Conclusions The Multi-InDel markers demonstrated high genetic polymorphisms in Chinese Kazakh and Kyrgyz ethnic groups, indicating their suitability for forensic applications. For the two ethnic groups, the cumulative power of discrimination (CPD) values were 0.999999999999999999999999835993 and 0.999999999999999999999999717184, respectively, while the cumulative power of exclusion (CPE) values were 0.999998887418153 and 0.999999348634116, respectively. Using this Multi-InDel panel, an average of 98.82% of full sibling (FS) pairs could be distinguished from unrelated individual pairs (likelihood ratio > 1). Regarding population genetics, Chinese Kazakh and Kyrgyz groups were found to exhibit an East Asia-Europe admixed ancestry pattern, while maintaining closer genetic affinities with East Asian populations.