Population genetics for 17 Y-STR loci(AmpFISTR®Y-filerTM) in Luzhou Han ethnic group

Genetic Polymorphism Analysis of 24 Y-STRs in a Han Chinese Population in Luzhou, Southwest China

Han is the largest of China's 56 ethnic groups and the most populous ethnic group in the world. The Luzhou region is located in southwest China, at the junction of three provinces. The unique historical factors contribute to the genetic polymorphism information. Short tandem repeats (STRs) are highly polymorphic, but the polymorphism of the Y chromosomal STRs (Y-STRs) loci in the Luzhou region is still unclear. It is of great significance to provide Y-STRs genetic data for the Han population from the Luzhou areas of southwest China. A total of 910 unrelated male individuals of the Han population from the Luzhou area were recruited, and 24 Y-STRs were analyzed. The population structure and phylogenetic relationships were compared with those of another 11 related Han populations. A total of 893 different haplotypes were achieved from 910 samples, of which 877 (98.21%) haplotypes were unique. Haplotype diversity and discrimination were 0.999956 and 0.981319, respectively. The lowest genetic diversity of DYS437 is 0.4321, and the highest genetic diversity of DYS385a/b is 0.9642. Pair-to-pair genetic distance and relative probability values indicate that Luzhou Han people are close to Sichuan Han people, Guangdong Han people, and Hunan Han people, which is consistent with geographical distribution, historical influence, and economic development. The 24 Y-STR markers of the southwest Luzhou Han population were highly polymorphic, which provided us with genetic polymorphism information and enriched the population genetic database. Therefore, it is of great value to our forensic applications and population genetics research.

Technical note: multi-alleles at the DYS385ab locus with high frequency in a Han Chinese population from southwestern China

Y-chromosome short tandem repeat (Y-STR) markers have been widely used in forensic applications and usually show monoallelic or diallelic genotypic patterns at certain double-copied loci. In this study, we have found 13 samples among 703 males with multi-alleles at the DYS385ab locus, including one with five mutant alleles, nine with four, and three with three. The frequency of abnormal DYS385ab genotypes was 1.85% (13/703), which is very high in the Han Chinese population. The percentage of samples with diallelic patterns at DYS385ab was higher than that of monoallelic patterns (80.23% vs. 17.92%). Additionally, the percentage of samples with tetra-allelic patterns at DYS385ab was higher than that of tri-allelic patterns (1.28% vs. 0.43%), suggesting that there are possibly two copies with duplicated events happening frequently on the Y chromosome. Interestingly, the peak height of allele 13 was two to three-folds higher than that of other alleles. The allele 18 peak height was also two-fold higher than others, which could potentially be explained by a duplication event mechanism. We also found that tri-allelic genotypes for alleles 13, 17, and 20, tetra-allelic genotypes for alleles 13, 14, 19, and 20, and tetra-allelic genotypes for alleles 12, 13, 19 and 21 were more common than others. Furthermore, all 13 samples had multi-alleles containing allele 13, implying a founder effect in this particular Chinese-specific ethnic group. Taken together, this study provides new information for this population and will be useful for paternal lineage identification, kinship analysis, and family relationship reconstruction using Y-STR forensic DNA analysis methods.

Revisiting the male genetic landscape of China: a multi-center study of almost 38,000 Y-STR haplotypes

China has repeatedly been the subject of genetic studies to elucidate its prehistoric and historic demography. While some studies reported a genetic distinction between Northern and Southern Han Chinese, others showed a more clinal picture of small differences within China. Here, we investigated the distribution of Y chromosome variation along administrative as well as ethnic divisions in the mainland territory of the People's Republic of China, including 28 administrative regions and 19 recognized Chinese nationalities, to assess the impact of recent demographic processes. To this end, we analyzed 37,994 Y chromosomal 17-marker haplotype profiles from the YHRD database with respect to forensic diversity measures and genetic distance between groups defined by administrative boundaries and ethnic origin. We observed high diversity throughout all Chinese provinces and ethnicities. Some ethnicities, including most prominently Kazakhs and Tibetans, showed significant genetic differentiation from the Han and other groups. However, differences between provinces were, except for those located on the Tibetan plateau, less pronounced. This discrepancy is explicable by the sizeable presence of Han speakers, who showed high genetic homogeneity all across China, in nearly all studied provinces. Furthermore, we observed a continuous genetic North-South gradient in the Han, confirming previous reports of a clinal distribution of Y chromosome variation and being in notable concordance with the previously observed spatial distribution of autosomal variation. Our findings shed light on the demographic changes in China accrued by a fast-growing and increasingly mobile population.

Genetic polymorphisms of 17 Y-chromosomal STRs in the Chengdu Han population of China

Chengdu is located at the center of Sichuan Province in southwestern China, and its primary demographic group is the Han population. The aim of this study was to contribute data detailing 17 Y-short tandem repeat (Y-STR) loci from 3291 Chengdu Han male samples analyzed with the AmpFLSTR^® Yfiler^® PCR Amplification Kit. We observed 2228 different haplotypes, and haplotype diversity (HD) was 0.9992. Gene diversity (GD) values for the 17 Y-STR loci of the Chengdu Han population ranged from 0.4156 to 0.9529. Haplotype match probability (HMC) was 0.0011. Compared with 13 reference populations of six provinces surrounding Chengdu, we observed that the Chengdu Han population was significantly different from each of these populations.

Detection of a novel X-chromosomal short tandem repeat marker in Xq28 in four ethnic groups

DNA testing of X-chromosomal short tandem repeat (X-STR) polymorphisms has been the focus of attention in several studies, mainly due to its applicability in the investigation of complex kinship cases. Studies of X-STR in analyses of DNA sequences, population studies and DNA testing applications have been reported. We performed detection and population genetic study of a novel tetranucleotide X-STR locus in the present study. We identified a unique X-STR locus consisting of two tetranucleotides in Xq28. Although the STR is a simple tetranucleotide, its polymorphism was comparatively high [polymorphism information content (PIC)=0.7140] in Japanese subjects. In addition, the STR varied in structure among ethnic groups. We conclude that this locus will be useful for forensic DNA testing and anthropological studies.

Genetic polymorphisms of 17 Y chromosomal STRs in She and Manchu ethnic populations from China

To evaluate the utility of Yfiler haplotype for DNA testing in two ethnic populations of China, a sample of 413 unrelated individuals (152 Shes and 261 Manchus) was determined. In the She and Manchu populations, the haplotype diversity was 0.9990 and 0.9988, respectively, and the discrimination capacity was 0.9474 and 0.9080, respectively. Research results will be valuable for human identification and paternity tests in the two minority regions and for Chinese population genetic study in the future.

Genetic analysis of 17 Y-STR loci in Han and Korean populations from Jilin Province, Northeast China

In this study, 17 Y chromosomal short tandem repeats (Y-STRs) were analyzed in 302 male individuals from the Chinese Han and Korean populations of Jilin Province. The haplotype diversities of two populations reached 0.99969 and 0.99874, respectively. The Jilin Han and Korean populations differed from each other significantly. The Jilin Han population showed no significant difference from almost any other Han population, but it did show significant differences from most other Chinese ethnic populations. The haplotype frequencies in the Jilin Korean population studied here showed significant differences from all reference populations in earlier reports. These data provide a reference for the Y-STR database in Jilin Province, and they may be valuable for population genetic analysis.

Analysis of 24 Y chromosomal STR haplotypes in a Chinese Han population sample from Henan Province, Central China

We analyzed haplotypes for 24 Y chromosomal STRs (Y-STRs), including 17 Yfiler loci (DYS19, DYS385a/b, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS437, DY438, DYS439, DYS448, DYS456, DYS458, DYS635 and Y-GATA-H4) and 7 additional STRs (DYS388, DYS444, DYS447, DYS449, DYS522 and DYS527a/b) in 1100 unrelated Chinese Han individuals from Henan Province using AGCU Y24 STR kit systems. The calculated average gene diversity (GD) values ranged from 0.4105 to 0.9647 for the DYS388 and DYS385a/b loci, respectively. The discriminatory capacity (DC) was 72.91% with 802 observed haplotypes using 17 Yfiler loci, by the addition of 7 Y-STRs to the Yfiler system, the DC was increased to 79.09% while showing 870 observed haplotypes. Among the additional 7 Y-STRs, DYS449, DYS527a/b, DYS444 and DYS522 were major contributors to enhancing discrimination. In the analysis of molecular variance, the Henan Han population clustered with Han origin populations and showed significant differences from other Non-Han populations. In the present study, we report 24 Y-STR population data in Henan Han population, and we emphasize the need for adding additional markers to the commonly used 17 Yfiler loci to achieve more improved discriminatory capacity in a population with low genetic diversity.

Understanding Y haplotype matching probability

The Y haplotype population-genetic terrain is better explored from a fresh perspective rather than by analogy with the more familiar autosomal ideas. For haplotype matching probabilities, versus for autosomal matching probabilities, explicit attention to modelling - such as how evolution got us where we are - is much more important while consideration of population frequency is much less so. This paper explores, extends, and explains some of the concepts of "Fundamental problem of forensic mathematics - the evidential strength of a rare haplotype match". That earlier paper presented and validated a "kappa method" formula for the evidential strength when a suspect matches a previously unseen haplotype (such as a Y-haplotype) at the crime scene. Mathematical implications of the kappa method are intuitive and reasonable. Suspicions to the contrary raised in rest on elementary errors. Critical to deriving the kappa method or any sensible evidential calculation is understanding that thinking about haplotype population frequency is a red herring; the pivotal question is one of matching probability. But confusion between the two is unfortunately institutionalized in much of the forensic world. Examples make clear why (matching) probability is not (population) frequency and why uncertainty intervals on matching probabilities are merely confused thinking. Forensic matching calculations should be based on a model, on stipulated premises. The model inevitably only approximates reality, and any error in the results comes only from error in the model, the inexactness of the approximation. Sampling variation does not measure that inexactness and hence is not helpful in explaining evidence and is in fact an impediment. Alternative haplotype matching probability approaches that various authors have considered are reviewed. Some are based on no model and cannot be taken seriously. For the others, some evaluation of the models is discussed. Recent evidence supports the adequacy of the simple exchangability model on which the kappa method rests. However, to make progress toward forensic calculation of Y haplotype mixture evidence a different tack is needed. The "Laplace distribution" model of Andersen et al. [3] which estimates haplotype frequencies by identifying haplotype clusters in population data looks useful.