Phylogenetic analyses of 41 Y-STRs and machine learning-based haplogroup prediction in the Qingdao Han population from Shandong province, Eastern China.

BACKGROUND: Known for its rich history and culture, Qingdao is a typical symbol of Chinese maritime culture. Its unique genetic landscape has aroused interest among geneticists and forensic scientists. However, the genetic landscape of Qingdao has never been uncovered. AIM: This investigation intends to provide light on Qingdao's paternal genetic diversity and its evolutionary connections to other Han subgroups. SUBJECTS AND METHODS: The genetic polymorphisms of 41 Y-chromosomal short tandem repeat (STR) loci in the Qingdao Han were investigated using SureID® PathFinder Plus Kit. Phylogenetic studies were performed using genotype data from 52 East Asian groups at 23 common Y-STR loci. A multidimensional scaling plot and cladogram were constructed. Linear Discriminant Analysis (LDA) was carried out for predicting categories among the Han people. The k-nearest neighbour (kNN) algorithm was utilised to designate Y-SNP haplogroups for each haplotype. RESULTS: The Qingdao Han were genetically far from the Tibeto-Burman populations and close with the Han people from northern China. LDA indicated a deep integration among the present-day Han people. By the kNN model, the predicted O2a2 and O2a1 were shown to be the predominant Y-SNP haplogroups. CONCLUSIONS: This study would be helpful for reconstructing the patrilineal history in China and establishing a more comprehensive Y-STR database.

Assessing the factors influencing the performance of machine learning for classifying haplogroups from Y-STR haplotypes.

Two distinct genetic markers, single nucleotide polymorphisms (Y-SNPs) and short tandem repeats (Y-STRs), exist simultaneously in the non-recombining portion of the Y chromosome. Because of their different rates of mutation, Y-STRs and Y-SNPs play distinct roles in forensic and evolutionary genetics. Current approaches to infer haplogroup status rely on genotyping lots of Y-SNP loci. Given the relationship between haplotype and haplogroup of a Y chromosome, a cost-effective strategy of Y-STRs typing had an advantage in haplogroup prediction. Many machine learning algorithms have sprung up for assigning a Y-STR haplotype to a haplogroup. However, a series of issues must be solved before the using of machine learning method in practice. Thus, the k-nearest neighbor (kNN) classifier was built respectively based on different situations in this study. We assessed different factors which may influence the performance of the kNN prediction model for classifying haplogroups. The training set was based on a diverse ground-truth data set comprising Y-STR haplotypes and corresponding Y-SNP haplogroups. Our results showed that combining different levels of haplogroups into the observations or transracial prediction was impractical. Moreover, using more slow mutation Y-STR loci in the category is good for promoting classification accuracy. The preconditions for an effective and accurate haplogroup assignment by the kNN classifier were revealed.

Phylogenetic analyses of the 19 STR loci in X chromosome revealed discriminant forensic characteristics for Chinese Daur and Oroqen minorities.

In respect of forensic genetics, X-STRs are widely applied for deficiency paternity cases. Given the popularization of AGCU-X19 STR Kit in China, there has been investigation conducted into the genetic data and forensic parameters of 19 X-STR loci in many of the Chinese ethnic groups, which makes it possible to perform nationwide phylogenetic comparation. To evaluate the allele and haplotype diversity of 19 X-STR loci and to explore their forensic efficiency in the Daur and Oroqen minorities, unrelated healthy Daur (n = 86) and Oroqen (n = 165) individuals were recruited from Heilongjiang province, so as to reveal the phylogenetic relationship between the two minorities and other Chinese ethnic groups. Of the Daur and Oroqen minorities, 172 and 183 alleles at the 19 X-STR loci were observed, respectively. Haplotype diversity exceeded 0.9 among all the linkage clusters. High cumulative value was observed for the power of discrimination, the probability of exclusion, and the mean exclusion chance for deficiency cases (normal trios and duo cases). As revealed by this study, the panel of 19 X-STR loci is an effective supplementary tool for the kinship test of the studied nationalities.

Developmental validation study of a 32-plex STR direct amplification system for forensic reference samples.

The STRtyper-32G PCR Amplification Kit is a 6-dye multiplex system that combines the 30 autosomal STR loci with an Indel site (YIndel) and the sex-determinant locus Amelogenin. In addition to more loci, Master Mix has been optimized to amplify DNA on different substrates. The autosomal STR loci contained in this novel system meet the compatibility of requirements for databasing. In this study, the developmental validation study of the STRtyper-32G Kit followed the guidelines of SWGDAM (Scientific Working Group on DNA Analysis Methods), including PCR-based studies, species specificity, inhibitors, sensitivity, precision, repeatability, stutter, DNA mixtures, concordance studies, and population genetics studies. The validation results indicate that the new multiplex system is a robust tool for forensic database applications.

Gene flow and phylogenetic analyses of paternal lineages in the Yi-Luo valley using Y-STR genetic markers.

BACKGROUND: The Yi-Luo valley witnessed the most significant socio-political transformation of China and was deeply implicated in several enormous migrations of the Han population. However, little has been done to clarify its paternal genetic variation or phylogenetic relationship, particularly concerning the genetic evidence of their migrations. AIM: This study aims to uncover the population genetic characteristics in the Yi-Luo valley and provide genetic evidence for its people's migrations. SUBJECTS AND METHODS: Seventeen Y-STR loci included in the AmpFlSTR®Yfiler™ were typed in 2,314 individuals from seven different regions along the Yi-Luo valley. A multidimensional scaling plot and neighbor-joining tree were constructed for nationwide genetic comparisons. Y-haplogroup frequencies and migration rates were estimated among the studied populations. Gene flows were detected by different migration models and directions. RESULTS: The predicted Y-haplogroups demonstrated the predominance of O2a2. Genetic affinities were observed among Han, Hakka, Danmin, and Bai. Anhui was shown to be the most crucial transfer spot for the Hakkas when they moved out of the Central Plains to South China. CONCLUSIONS: This study reveals the genetic landscape of paternal lineages living in the Yi-Luo valley and enriches our understanding of the great migration in Chinese history.

Forensic and phylogenetic analyses of populations in the Tibetan-Yi corridor using 41 Y-STRs.

Y-chromosome haplotypes of 527 non-related males (176 Han, 186 Tibetan, and 165 Yi) in the Tibetan-Yi corridor were analyzed using SureID® PathFinder Plus. In the populations of Han, Tibetans, and Yi, the haplotype diversity was 0.9989, 0.9981, and 0.9993, respectively, and the discrimination capacity was 0.9148, 0.8925, and 0.9576, respectively. Phylogenetic relationships among 12 studied ethnic groups and 7 other ethnic groups in the Tibetan-Yi corridor were investigated. Both multi-dimensional scaling analysis and phylogenetic reconstructions indicated that Tibetans appeared separated from the Han and Yi ethnic groups in the Tibetan-Yi corridor. Their genetic homogeneity or heterogeneity has not entirely been affected by their geographical distance and linguistic origin.

Phylogenic analysis and forensic genetic characterization of Guizhou Miao tribes from 58 microareas via autosomal STR.

Genetic polymorphism of 17 autosomal short tandem repeat (STR) loci, included in the PowerPlex®18D amplification kit, were analyzed in Miao tribes from 58 different sampling microareas (N = 5255) of Guizhou as well as two cities (N = 151) of Hunan, China. Allele frequencies and forensic efficiency parameters were calculated. Moreover, comprehensive population genetic comparisons among 91 nationwide populations and 174 Asian populations were conducted based on raw genotype data and allele frequency data, respectively. Our results of forensic efficiency parameters showed that the panel was a robust tool in forensic individual identification and paternity cases for this population. Genetic affinities were observed among most of the Miao tribes revealed by multidimensional scaling plot, principal component analysis, and neighboring-joining tree. The genetic distance between Miao tribes and Han nationalities were varies by different geographical positions. Some of the Miao tribes were genetically closer to the Hmong-Mien populations living in southeastern contiguous regions and even the Indochina. The result coincided with the migration or reverse migration routes for Miao nationality in modern history. This study of the Miao tribes from plenty of microareas in Guizhou would be useful in reconstructing the population history and establishing a more comprehensive forensic reference database.

Forensic and phylogenetic analyses among three Yi populations in Southwest China with 27 Y chromosomal STR loci.

We have analyzed the Y chromosome haplotypes of 510 non-related Yi males grouped in three Chinese provinces (Guizhou, Sichuan, and Yunnan) using the Yfiler® Plus Kit. A total of 484 haplotypes were detected, out of which 460 were unique. The observed haplotype diversity and discrimination capacity were 0.9998 and 0.9490, respectively. To investigate the genetic relationship of the studied population, multidimensional scaling (MDS) plot and neighbor-joining (NJ) tree phylogenetic analyses were constructed which demonstrated that the Y chromosome lineage among the Yi ethnicity was different.

Detecting a hierarchical genetic population structure via Multi-InDel markers on the X chromosome.

Detecting population structure and estimating individual biogeographical ancestry are very important in population genetics studies, biomedical research and forensics. Single-nucleotide polymorphism (SNP) has long been considered to be a primary ancestry-informative marker (AIM), but it is constrained by complex and time-consuming genotyping protocols. Following up on our previous study, we propose that a multi-insertion-deletion polymorphism (Multi-InDel) with multiple haplotypes can be useful in ancestry inference and hierarchical genetic population structures. A validation study for the X chromosome Multi-InDel marker (X-Multi-InDel) as a novel AIM was conducted. Genetic polymorphisms and genetic distances among three Chinese populations and 14 worldwide populations obtained from the 1000 Genomes database were analyzed. A Bayesian clustering method (STRUCTURE) was used to discern the continental origins of Europe, East Asia, and Africa. A minimal panel of ten X-Multi-InDels was verified to be sufficient to distinguish human ancestries from three major continental regions with nearly the same efficiency of the earlier panel with 21 insertion-deletion AIMs. Along with the development of more X-Multi-InDels, an approach using this novel marker has the potential for broad applicability as a cost-effective tool toward more accurate determinations of individual biogeographical ancestry and population stratification.

[Advances in identification of semen stains].

Stain identification has long been a task in forensic biology. The identification of semen stain, one of the most common human stains, can provide crucial information for crime scene reconstruction and forensic investigation. Traditional detection of semen stain depends largely on the microscopic identification of spermatozoa, enzyme activity-based methods or antigen-antibody reactions. These morphological, proteinological and zymological approaches, however, are apparently inadequate in identifying tiny, admixed, degraded or contaminated samples. With the development of transcriptomics and epigenetics, many semen-specific mRNA markers, such as protamine-1 (PRM1) and -2 (PRM2), have been applied to semen and semen stain identification. Messenger RNA profiling shows great promise in identifying tissues as demonstrated by the recognition of specific markers. Further more, studies on tis-sue-specific differential DNA methylation will provide a scrumptious way of identifying difficult samples.