Population genetic analysis of insertion–deletion polymorphisms in a Brazilian population using the Investigator DIPplex kit

Population Genetic Data of 30 Insertion-Deletion Markers in the Polish Population

(1) Background: Insertion-deletion (InDel) markers show the advantages of both short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs) and are considered alternative markers in forensic genetics. (2) Methods: Allelic frequencies and corresponding forensic efficiency parameters of 30 autosomal polymorphic InDel loci included in the Investigator DIPplex kit (Qiagen) were obtained in a sample of 631 unrelated Polish individuals. Allelic frequency data were compared with those reported for selected populations (3) Results: All the loci conformed with Hardy-Weinberg equilibrium after applying a Bonferroni correction and no pair-wise significant linkage disequilibrium was detected. (4) Conclusions: DIPplex Kit differences were high among populations worldwide. The InDel markers are highly discriminating for human identification purposes in the Polish population.

Genetic Admixture History and Forensic Characteristics of Guizhou Sui People Inferred From Autosomal Insertion/Deletion and Genome-Wide Single-Nucleotide Polymorphisms

Insertion-deletion (Indel) serves as one of the important markers in forensic personal identification and parentage testing, especially for cases with degraded samples. However, the genetic diversity and forensic features in ethnolinguistically diverse southwestern Chinese populations remain to be explored. Sui, one Tai-Kadai-speaking population residing in Guizhou, has a complex genetic history based on linguistic, historic, and anthropological evidence. In this study, we genotyped 30 Indels from 511 Guizhou Sui individuals and obtained approximately 700,000 genome-wide single-nucleotide polymorphisms (SNPs) in 15 representative Sui individuals to comprehensively characterize the genetic diversity, forensic characteristics, and genomic landscape of Guizhou Sui people. The estimated forensic statistically allele frequency spectrum and parameters demonstrated that this Indels panel was polymorphic and informative in Tai-Kadai populations in southern China. Results of principal component analysis (PCA), STRUCTURE, and phylogenetic trees showed that Guizhou Sui had a close genetic relationship with geographically close Tai-Kadai and Hmong-Mien people. Furthermore, genomic analysis based on the Fst and f4-statistics further suggested the genetic affinity within southern Chinese Tai-Kadai-speaking populations and a close relationship with geographically adjoining Guizhou populations. Admixture models based on the ADMIXTURE, f4, three-way qpAdm, and ALDER results demonstrated the interaction between the common ancestor for Tai-Kadai/Austronesian, Hmong-Mien, and Austroasiatic speaking populations played a significant role in the formation of modern Tai-Kadai people. We observed a sex-biased influence in Sui people by finding that the dominant Y chromosomal type was a Hmong-Mien specific lineage O2a2a1a2a1a2-N5 but the mtDNA lineages were commonly found in Tai-Kadai populations. The additional southward expansion of millet farmers in the Yellow River Basin has impacted the gene pool of southern populations including Tai-Kadai. The whole-genome sequencing in the future will shed more light on the finer genetic profile of Guizhou populations.

Spanish allele and haplotype database for 32 X-chromosome Insertion-Deletion polymorphisms

X-chromosome markers have been proved to be decisive both complementing and solving kinship analysis, particularly when autosomal markers are not able to produce adequate likelihood ratios between different hypothesis. On the other hand, Pereira et al., (2012) have demonstrated that 32 Insertion/Deletion (InDel) markers located on the X-Chromosome have a very important power of discrimination in human populations, being a novel tool in the forensic and population fields. So, the aim of the present work was testing the forensic and population genetic efficiency of the 32 X-InDel polymorphisms in the Spanish population, and subsequently build an allele/haplotype frequencies database. To accomplish this objective, a total of 555 samples comprising male individuals from 13 Spanish regions were analysed for the above mentioned 32 X-InDels in two independent laboratories. A pairwise F_ST analysis was performed in order to understand if the studied Spanish sub-populations present significant differences among them, detecting possible population substructure. Also, linkage disequilibrium analyses were computed to investigate the presence of association between markers in the Spanish population. After Bonferroni correction, the absence of significant differences among the studied regions supports a global Spanish population database. Concerning LD, besides previously reported linked markers MID356-MID357 and MID3690-MID3719-MID2089, we also detected significant association between MID3703-MID3774, even after Bonferroni correction. Finally, after computing allele and haplotype frequencies, forensic efficiency parameters were calculated (PD_males = 99.999976 %; PD_females = 99.99999999998 %). Mean exclusion chance values for duos were 0.999 and trios 0.99999. These results reinforce the suitability of the 32 X-InDels marker set both in identification and kinship studies.

Genetic diversity and phylogenetic analysis of Chinese Han and Li ethnic populations from Hainan Island by 30 autosomal insertion/deletion polymorphisms

With the characteristics of low mutation rate, length variation and short amplicon size, insertion/deletion polymorphisms (InDels) have the advantages of both short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs). Herein, people of two ethnicities from Hainan Island were genotyped for the first time using the Investigator DIPplex kit. We investigated the forensic parameters of the 30 InDels and the phylogenetic relationships among different populations. The accumulated powers of discrimination and powers of exclusion were 0.999 999 999 9646 and 0.9897 in the Hainan Han population and 0.999 999 999 9292 and 0.9861 in the Hainan Li population, respectively. Additionally, population comparisons among geographically, ethnically and linguistically diverse populations via cluster heatmap, multidimensional scaling, principal component analysis, phylogenetic tree and STRUCTURE analyses demonstrated that the Hainan Han population had genetic similarities to the other Han, She and Tujia populations, while the Hainan Li population had close genetic relationships to the Zhuang and Miao groups; both populations had a high degree of genetic differentiation from most Turkic-speaking populations. Aforementioned results suggested that the 30 autosomal InDels are highly polymorphic and informative, which are suitable for human identification and population genetics.

Four hundred and forty-five Chinese individuals from two ethnicities (Hainan Han and Hainan Li) were firstly analyzed by 30 autosomal InDels included in the Investigator DIPplex panel.

Forensic parameters of the 30 InDels in the two populations showed high polymorphism and universality for human identification purposes.

The Investigator DIPplex panel had a certain capacity of differentiating intercontinental populations and different language populations.

Full mtDNA genome sequencing of Brazilian admixed populations: A forensic-focused evaluation of a MPS application as an alternative to Sanger sequencing methods

The use of Massive Parallel Sequencing (MPS) techniques have been proposed by the forensic community as an alternative to Sanger sequencing methods in routine forensic casework analysis regarding mitochondrial DNA (mtDNA). Interesting features of MPS include high throughput, ability to simultaneously genotype a significant number of samples by barcoding techniques, processing automation, reduced time and costs, among others. Advantages include the capability of generating full mtDNA genome sequences versus usual techniques, usually limited to hypervariable or control regions exclusively. In this work, 96 reference single-source samples from three different Brazilian cities were subjected to full mtDNA genome sequencing by MPS techniques using an early-access version of Precision ID mtDNA Whole Genome Panel on an Ion Torrent PGM platform (Thermo Fisher Scientific, Waltham, MA, USA). Complete, high-quality sequences were obtained and sequencing performance was evaluated via four different metrics. As a subset of evaluated samples have been previously submitted for Sanger sequencing of the control region, a comparative analysis of both methods' results was conducted in order to compare technique adequacy within a forensic context. Even though this study is one of the first to report full mtDNA genome sequences for Brazilian admixed populations, the observed haplotypes exhibit a predominance of Native American and African maternal lineages in the studied sample set, reproducing results described in the literature for control regions only. Interpopulation analysis among Brazilian and 26 worldwide populations was also carried out. The results indicate that MPS-generated full mtDNA genome sequences may have great utility in forensic real casework applications, with a pronounced gain of genetic information and discrimination power provided by coding region evaluation and the enhanced capacity of heteroplasmies determination. Database construction and other relevant factors concerning implementation of such techniques in Brazilian forensic laboratories are also discussed.

A GHEP-ISFG collaborative study on the genetic variation of 38 autosomal indels for human identification in different continental populations

A collaborative effort was carried out by the Spanish and Portuguese Speaking Working Group of the International Society for Forensic Genetics (GHEP-ISFG) to promote knowledge exchange between associate laboratories interested in the implementation of indel-based methodologies and build allele frequency databases of 38 indels for forensic applications. These databases include populations from different countries that are relevant for identification and kinship investigations undertaken by the participating laboratories. Before compiling population data, participants were asked to type the 38 indels in blind samples from annual GHEP-ISFG proficiency tests, using an amplification protocol previously described. Only laboratories that reported correct results contributed with population data to this study. A total of 5839 samples were genotyped from 45 different populations from Africa, America, East Asia, Europe and Middle East. Population differentiation analysis showed significant differences between most populations studied from Africa and America, as well as between two Asian populations from China and East Timor. Low F_ST values were detected among most European populations. Overall diversities and parameters of forensic efficiency were high in populations from all continents.

Study of InDel genetic markers with forensic and ancestry informative interest in PALOP's immigrant populations in Lisboa

The migratory phenomenon in Portugal has become one of the main factors for the genetic variability. In the last few years, a new class of autosomal insertion/deletion markers-InDel-has attracted interest in forensic genetics. Since there is no data for InDel markers of Portuguese-speaking African countries (PALOP) immigrants living in Lisboa, our aim is the characterization of those groups of individuals by typing them with at least 30 InDel markers and to compare different groups of individuals/populations. We studied 454 bloodstain samples belonging to immigrant individuals from Angola, Guinea-Bissau, and Mozambique. DNA extraction was performed with the Chelex® 100 method. After extraction, all samples were typed with the Investigator® DIPplex method. Through the obtained results, allelic frequencies show that all markers are at Hardy-Weinberg equilibrium, and we can confirm that those populations show significant genetic distances between themselves, between them, and the host Lisboa population. Because of this, they introduce genetic variability in Lisboa population.