Phylogenetic analysis and forensic characteristics of 12 populations using 23 Y-STR loci

Genetic analysis of Y-STRs has the potential to be used to explore the complexity in population substructures and to perform forensic ancestry inference. In this study, 334 individuals from 12 populations were typed using the PowerPlex^® Y23 System (Promega, USA) to investigate their relationship. Population comparisons with other East Asian populations collated from YHRD (Y-STR Haplotype Reference Database) were also performed. Variant alleles, including seven intermediate alleles in 15 samples were observed, while the novel allele 11.3 at the DYS549 locus was confirmed by sequencing. Our results showed that the fraction of unique haplotypes differed among the 12 populations studied here. A close relationship was found between Chinese and other East Asian populations. The present study contributed to the enrichment of the forensic Y-chromosome databases with a high resolution 23 Y-STR marker set, which is informative in forensic casework, such as familial searching and estimating the geographical origin of the offender.     

Developmental validation of the DNATyper™Y26 PCR amplification kit: An enhanced Y-STR multiplex for familial searching

The DNATyper^™Y26 PCR Amplification kit, which including 26 low-medium mutating Y-STRs, is designed for Y-STR familial searching casework. The kit combines nine new Y-STR loci in addition to the 17 Y-STR loci from the commercially available AmpFlSTR®Yfiler® kit. The validation of the DNATyper^™Y26 kit was performed in terms of technical index, including accuracy, stability, species specificity, sensitivity, adaptability for various samples, and mixture. Further, mutations of the 26 Y-STRs were analyzed by 1167 DNA-confirmed father-son pairs, and the results indicated that these loci had low or medium mutation rates. Furthermore, these Y-STRs loci were also tested in 1072 random male samples from Henan, Shanxi, Inner Mongolia, and Chongqing in China, showing their high power for forensic discrimination in the Chinese population. Thus, the DNATyper^™Y26 PCR Amplification kit is a powerful tool for ‘Y-STRs familial searching’ in actual sexual-assault cases, indicating its unique advantage in familial searching due to Y-STR loci with only low-medium mutation rates.     

Extending STR markers in Y chromosome haplotypes

Two multiplex reactions were developed to amplify 16 Y-STRs (DYS19, DYS385, DYS389 I and II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, GATA A7.1, GATA A7.2, GATA A10, GATA C4, GATA H4). Here we extend previous population studies done in a sample from northern Portugal for the GATA A7.1, GATA A7.2, GATA C4 and GATA H4 loci. A total of 199 different haplotypes identified by the 16 Y-STR markers were observed in a sample of 208 male individuals, of which 190 were unique and 9 were found twice. The overall haplotype diversity was 0.9996. The haplotype diversity of the Y-STR set composed of the 8 new markers is higher than the Y-STR core set included in the Y-STR haplotype reference database. Sequence structure of new alleles for GATA C4 and GATA H4 is reported. The usefulness of the inclusion of this new set of Y-STRs in forensic casework was also assessed. The increase in haplotype diversity with the addition of any new Y-STR marker to the 8 Y-STR core set is dependent not only on the gene diversity (positively) but also (negatively) on the degree of gametic association between the markers and the haplotypes previously defined. For instance, in our sample the addition of the DYS437, DYS438 and GATA A7.2 to a 13-locus set increased haplotype diversity only by 0.0001.     

Seventeen Y-chromosomal short tandem repeat haplotypes in seven groups of population living in Taiwan

The analysis of Y-chromosome short tandem repeat (Y-STR) loci is a powerful tool in forensic casework. The aim of this study was to present the 17 Y-STR loci haplotype distributions of groups of population living in Taiwan and to demonstrate genetic distances between the groups as well as multidimensional scaling plot based on Y-STR genotype data. Five hundred and fifteen DNA samples from unrelated males of seven groups of population, including Taiwanese Han, two groups of indigenous Taiwanese of Taiwan Island, Tao, mainland Chinese, Filipinos, and a group of people with European, Near Eastern, or South Asian ancestry, were analyzed using a commercial kit that co-amplifies 17 Y-STRs. A total of 471 different haplotypes with 440 unique haplotypes were identified. The overall haplotype diversity was 0.9995 ± 0.0002. High haplotype diversity was observed in six groups of population, except the Tao. These Y-STRs revealed a low discrimination capacity in the Tao population (36.84%), which should be considered in forensic practice. The multidimensional scaling plot of these seven groups of population constructed based on the genetic distances according to 17 Y-STR loci presented a clear patrilineal genetic substructure in the area. Partial Y-STRs profiling reduced the discrimination capacity in most groups of population and distorted the multidimensional scaling plot.     

Analysis of seventeen Y-chromosome STR loci in the Cape Muslim population of South Africa

Two Y-STR genotyping systems were evaluated for usefulness in forensic casework in the Cape Muslim population of South Africa. Samples were collected from 105 males, and genotyped for 17 loci amplified in two multiplexes. Allele and haplotype frequencies were determined for nine Y-STR loci used to define the minimal haplotype (DYS19, DYS389-I, DYS389-II, DYS390, DYS391, DYS392, DYS393, and the duplicated locus DYS385) amplified in one multiplex, as well as for eight widely used loci amplified in a second multiplex and consisting of DYS449, DYS481, DYS518, DYS557, DYS570, DYS607, DYS612 and DYS614. When analysing the samples for all the loci, 104 unique haplotypes were obtained, and the discrimination capacity was 0.990. When considering only the nine Y-STRs included in the minimal haplotype, 91 unique haplotypes were obtained, and the discrimination capacity was 0.866. In the case of the remaining eight Y-STR loci, values of 97 and 0.924 were obtained, respectively.     

Y-Chromosome multiplexes and their potential for the DNA profiling of Koreans

We have developed four multiplex genotyping systems (GeneKin Y-STR multiplexes) using silver staining with allelic ladders for ten Y-chromosome STR markers (DYS19, DYS385, DYS388, DYS389I/II, DYS390, DYS391, DYS392, DYS393 and DXYS156Y), with a view towards the application of rapid and simple genotyping assay methods for DNA profiling. The GeneKin Y-STR multiplexes developed have followed the published nomenclature and ISFG guidelines for STR analysis. Allele and haplotype frequencies at these Y-STRs loci were analysed by PCR amplification using the GeneKin Y-STR multiplexes, followed by denaturing polyacrylamide gel electrophoresis in 316 unrelated males in the Korean population. A total of 295 different haplotypes were found, 279 of them being unique. Gene diversity ranged from 0.4026 at DYS391 to 0.9606 at DYS385. The haplotype diversity value (which is the same as the discrimination index) calculated from all ten loci combined was 0.9995, which is informative. Our results revealed that a set of ten Y-STRs can discriminate between most of the male individuals in the Korean population (discrimination capacity: 93.35%). The Y-STR multiplexes thus provide useful information for forensic analysis and paternity tests and can also be of great benefit for providing information not normally available from autosomal DNA systems. Received: 12 March 2001 / Accepted: 26 June 2001     

A new future of forensic Y-chromosome analysis: rapidly mutating Y-STRs for differentiating male relatives and paternal lineages

The panels of 9-17 Y-chromosomal short tandem repeats (Y-STRs) currently used in forensic genetics have adequate resolution of different paternal lineages in many human populations, but have lower abilities to separate paternal lineages in populations expressing low Y-chromosome diversity. Moreover, current Y-STR sets usually fail to differentiate between related males who belong to the same paternal lineage and, as a consequence, conclusions cannot be drawn on the individual level as is desirable for forensic interpretations. Recently, we identified a new panel of rapidly mutating (RM) Y-STRs, composed of 13 markers with mutation rates above 1 × 10(-2), whereas most Y-STRs, including all currently used in forensics, have mutation rates in the order of 1 × 10(-3) or lower. In the present study, we demonstrate in 604 unrelated males sampled from 51 worldwide populations (HGDP-CEPH) that the RM Y-STRs provide substantially higher haplotype diversity and haplotype discrimination capacity (with only 3 haplotypes shared between 8 of the 604 worldwide males), than obtained with the largest set of 17 currently used Y-STRs (Yfiler) in the same samples (33 haplotypes shared between 85 males). Hence, RM Y-STRs yield high-resolution paternal lineage differentiation and provide a considerable improvement compared to Yfiler. We also find in this worldwide dataset substantially less genetic population substructure within and between geographic regions with RM Y-STRs than with Yfiler Y-STRs. Furthermore, with the present study we provide enhanced data evidence that the RM Y-STR panel is extremely successful in differentiating between closely and distantly related males. Among 305 male relatives, paternally connected by 1-20 meiotic transfers in 127 independent pedigrees, we show that 66% were separated by mutation events with the RM Y-STR panel whereas only 15% were with Yfiler; hence, RM Y-STRs provide a statistically significant 4.4-fold increase of average male relative differentiation relative to Yfiler. The RM Y-STR panel is powerful enough to separate closely related males; nearly 50% of the father and sons, and 60% of brothers could be distinguished with RM Y-STRs, whereas only 7.7% and 8%, respectively, with Yfiler. Thus, by introducing RM Y-STRs to the forensic genetic community we provide important solutions to several of the current limitations of Y chromosome analysis in forensic genetics.     

Improving the regional Y-STR haplotype resolution utilizing haplogroup-determining Y-SNPs and the application of machine learning in Y-SNP haplogroup prediction in a forensic Y-STR database: A pilot study on male Chinese Yunnan Zhaoyang Han population

Improving the resolution of the current widely used Y-chromosomal short tandem repeat (Y-STR) dataset is of great importance for forensic investigators, and the current approach is limited, except for the addition of more Y-STR loci. In this research, a regional Y-DNA database was investigated to improve the Y-STR haplotype resolution utilizing a Y-SNP Pedigree Tagging System that includes 24 Y-chromosomal single nucleotide polymorphism (Y-SNP) loci. This pilot study was conducted in the Chinese Yunnan Zhaoyang Han population, and 3473 unrelated male individuals were enrolled. Based on data on the male haplogroups under different panels, the matched or near-matching (NM) Y-STR haplotype pairs from different haplogroups indicated the critical roles of haplogroups in improving the regional Y-STR haplotype resolution. A classic median-joining network analysis was performed using Y-STR or Y-STR/Y-SNP data to reconstruct population substructures, which revealed the ability of Y-SNPs to correct misclassifications from Y-STRs. Additionally, population substructures were reconstructed using multiple unsupervised or supervised dimensionality reduction methods, which indicated the potential of Y-STR haplotypes in predicting Y-SNP haplogroups. Haplogroup prediction models were built based on nine publicly accessible machine-learning (ML) approaches. The results showed that the best prediction accuracy score could reach 99.71% for major haplogroups and 98.54% for detailed haplogroups. Potential influences on prediction accuracy were assessed by adjusting the Y-STR locus numbers, selecting Y-STR loci with various mutabilities, and performing data processing. ML-based predictors generally presented a better prediction accuracy than two available predictors (Nevgen and EA-YPredictor). Three tree models were developed based on the Yfiler Plus panel with unprocessed input data, which showed their strong generalization ability in classifying various Chinese Han subgroups (validation dataset). In conclusion, this study revealed the significance and application prospects of Y-SNP haplogroups in improving regional Y-STR databases. Y-SNP haplogroups can be used to discriminate NM Y-STR haplotype pairs, and it is important for forensic Y-STR databases to develop haplogroup prediction tools to improve the accuracy of biogeographic ancestry inferences.     

Genetic polymorphisms and haplotypic structure analysis of the Guizhou Gelao ethnic group based on 35 Y-STR loci

In this research, 35 Y-chromosomal short tandem repeat (Y-STR) loci were analyzed in 286 unrelated healthy Gelao male individuals from Guizhou Province, China. Allelic and haplotype frequencies, haplotype diversity (HD), haplotype match probability (HMP), and discrimination capacity (DC) values were computed. Pairwise Rst values were assessed by AMOVA analysis and visualized through multidimensional scaling and neighbor-joining tree construction. A total of 609 alleles were detected at the 35 Y-STR loci, and the allelic frequencies ranged from 0.0035 to 0.8322. The HD, HMP, and DC were 0.9999, 0.0036, and 0.9825, respectively. A total of 281 haplotypes were found at 35 loci in the 286 Gelao individuals, 98.25% of which were unique. Related forensic parameters revealed that this panel of 35 loci had a high level of genetic polymorphisms in the Gelao group. However, the use of multi-copy and rapidly mutating Y-STR loci could significantly increase the discrimination power of a common Y-STR panel. Analyses of population differentiation with the same set of common Y-STR loci demonstrated that the Gelao group has a closer genetic relationship with the Guizhou Han and Guizhou Miao groups than other groups.     

Development of an Italian RM Y-STR haplotype database: Results of the 2013 GEFI collaborative exercise

Recently introduced rapidly mutating Y-chromosomal short tandem repeat (RM Y-STR) loci, displaying a multiple-fold higher mutation rate relative to any other Y-STRs, including those conventionally used in forensic casework, have been demonstrated to improve the resolution of male lineage differentiation and to allow male relative separation usually impossible with standard Y-STRs. However, large and geographically-detailed frequency haplotype databases are required to estimate the statistical weight of RM Y-STR haplotype matches if observed in forensic casework. With this in mind, the Italian Working Group (GEFI) of the International Society for Forensic Genetics launched a collaborative exercise aimed at generating an Italian quality controlled forensic RM Y-STR haplotype database. Overall 1509 male individuals from 13 regional populations covering northern, central and southern areas of the Italian peninsula plus Sicily were collected, including both “rural” and “urban” samples classified according to population density in the sampling area. A subset of individuals was additionally genotyped for Y-STR loci included in the Yfiler and PowerPlex Y23 (PPY23) systems (75% and 62%, respectively), allowing the comparison of RM and conventional Y-STRs. Considering the whole set of 13 RM Y-STRs, 1501 unique haplotypes were observed among the 1509 sampled Italian men with a haplotype diversity of 0.999996, largely superior to Yfiler and PPY23 with 0.999914 and 0.999950, respectively. AMOVA indicated that 99.996% of the haplotype variation was within populations, confirming that genetic-geographic structure is almost undetected by RM Y-STRs. Haplotype sharing among regional Italian populations was not observed at all with the complete set of 13 RM Y-STRs. Haplotype sharing within Italian populations was very rare (0.27% non-unique haplotypes), and lower in urban (0.22%) than rural (0.29%) areas. Additionally, 422 father-son pairs were investigated, and 20.1% of them could be discriminated by the whole set of 13 RM Y-STRs, which was very close to the theoretically expected estimate of 19.5% given the mutation rates of the markers used. Results obtained from a high-coverage Italian haplotype dataset confirm on the regional scale the exceptional ability of RM Y-STRs to resolve male lineages previously observed globally, and attest the unsurpassed value of RM Y-STRs for male-relative differentiation purposes.     

Population genetic data of 4 multicopy Y-STR markers in Chinese

Novel Y chromosomal STR (Y-STR) markers have been continuously discovered during the past decades, promoting the widely application of Y-STRs in the area of forensic science. Here, four multicopy Y-STR markers were focused, including DYF383S1, DYF409S1, DYF411S1 and DYF371, which are rarely reported in China and differ in the number of copies on Y chromosome. Characterization of the markers was performed in population of Hunan province, China, based on sequence analysis. Allele nomenclature and allelic ladder were then developed to avoid the disunity of typing standard. To evaluate their forensic performance, gene diversity of the four loci was investigated in 548 unrelated male individuals from Hunan population. The number of haplotype was analyzed by both conservative (C-type) and expanded approach (E-type) for markers containing more than 2 copies. As detected, there were 7, 9, 13 alleles and 15, 22, 23 haplotypes for DYF383S1, DYF409S1 and DYF411S1, respectively. Thirty-two C-types and 56 E-types were found in DYF371, indicating the highest haplotype diversity (HD) among all tested loci (0.871 and 0.888 for C-type and E-type, respectively). Two other Y-STRs (DYF409S1, DYF411S1) also showed high haplotype diversity (>0.8) in the population. Combining the four loci, discrimination capacity reached 0.505 (C-type) or 0.533 (E-type), and the total HD values exceeded 0.991. The results inferred great potential of the multicopy markers to improve the resolution of paternal identification in China population.     

Analysis of mutation rates and haplotypes of 23 Y-chromosomal STRs in Korean father–son pairs

Y-chromosomal short tandem repeats (Y-STRs) have been widely used in forensic genetics, and accurate knowledge of mutation rates at Y-STR loci is essential in kinship analysis. The main aim of this study was to estimate Y-STR mutation rates in Korean males. To obtain locus-specific mutations and haplotypes at 23 Y-STRs, we analyzed samples from 620 Korean father–son pairs. In addition, we also analyzed 476 unrelated individuals using the PowerPlex® Y23 System, with the aim of augmenting the available data for the Korean population. The PowerPlex® Y23 system facilitates analysis of the 23 Y-STR loci (DYS576, DYS570, DYS458, DYS635, DYS389 II, DYS549, DYS385, DYS481, DYS439, DYS456, DYS389 I, DYS19, DYS393, DYS391, DYS533, DYS437, DYS390, Y GATA H4, DYS448, DYS438, DYS392, and DYS643). Locus-specific mutation rate estimates varied from 0.00 to 8.06 × 10⁻³ per generation, with an average mutation rate of 2.17 × 10⁻³ (95% CI, 1.5–3.1 × 10⁻³). To obtain comprehensive genetic values for the Korean population, we combined data obtained in this study with previously reported values, thereby enabling us to estimate the locus-specific mutation rates regarding 22,711 allele transmissions. By combining these data, we obtained an overall average mutation rate of 2.91 × 10⁻³ (95% CI, 2.3–3.7 × 10⁻³). In addition, among the 476 unrelated Korean males, we detected 467 different haplotypes, with an overall haplotype diversity value of 0.9999. By extracting haplotypes of Y-STRs described in previous literature on 23 Y-STR reported in Korea, we obtained gene diversities for 1133 Korean individuals. We believe that the values and characteristics of the 23 Y-STRs analyzed in this study will contribute to establishing criteria for forensic genetic interpretation, including kinship analysis.     

Relating two deep-rooted pedigrees from Central Germany by high-resolution Y-STR haplotyping

Y-STR haplotyping is a powerful forensic and anthropological tool for identifying male lineages. We used high-resolution Y-STR haplotyping to evaluate the possibility of a blood relationship between two deep-rooted paternal genealogies with the same surname and originating from the same geographical region in Central Germany. One pedigree comprised 13 generations covering >450 years, the other comprised nine generations covering >300 years. Of the 68 loci tested, 64 (94%) consistently had the same allele in all males in the two pedigrees (except for some unambiguously sporadic mutations within pedigrees). Only four Y-STRs had a consistent allelic difference of exactly one repeat between the two pedigrees. These findings suggested that the two pedigrees were paternally related, and a conservative assessment taking average mutation rates and the available local haplotype frequencies for nine loci into account yielded a likelihood ratio of 8.2:1 in favour of this hypothesis. Our study thus highlights the power of Y-STR haplotyping to identify male lineages. It also shows that families can be linked to common ancestors on the basis of Y-STR data, even if these individuals lived several hundred years ago. However, the potential of Y-STR haplotyping could still not be fully exploited in our case due to a lack of appropriate population frequency data for all analysed Y-STR loci. This shortcoming makes a strong case for more comprehensive haplotype databases, including more samples and larger numbers of loci.     

Presentation of 17 Y-chromosomal STRs in the population of the Sverdlovsk region

We established a data set of 17 Y-STRs (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385a/b, DYS438, DYS439, DYS437, DYS448, DYS456, DYS458, DYS635 and Y-GATA-H4) of 832 unrelated males from the Sverdlovsk region, Russian Federation. In total we observed 773 different haplotypes of which 732 were unique and 41 occurred between two and nine times in the investigated population. The haplotype diversity was 0.9981 and the discrimination capacity was 0.9291. This study represents the Y-STR reference data set for forensic applications in the Sverdlovsk region.     

Y chromosomal STRs haplotypes in two populations from Bolivia

In the present study, we typed our previously reported two microsatellite markers, DXYS241 and DXYS266 together with a basic set of nine Y-STRs (DYS19, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DXYS156Y, DYS413) on Y chromosomes from two Bolivian populations. Unrelated males from communities living at high- (N=59) and low- (N=142) altitude, were studied. Combining the alleles into 11 Y-STRs haplotypes revealed that the high-altitude population is significantly less diverse than the low-altitude population. Haplotype diversities of 0.927+/-0.029 and 0.996+/-0.002 were found within the high-altitude, and the low-altitude populations, respectively. Within the high-altitude population 40 haplotypes were detected, whereas in the low-altitude population 113 haplotypes were found. Only three haplotypes were shared between both populations. Haplotyping-based discrimination using the 11 Y-STRs including our new two microsatellite markers DXYS241 and DXYS266 was shown to be powerful than using the conventional 9 Y-STRs, especially for the low-altitude Bolivian population. This 11 Y-STRs-based haplotyping system shows a very high potential for discrimination and could provide an ideal tool for forensic analysis and population studies. Moreover, this study includes data about two Bolivian populations which were not previously reported, this will help in building a world-wide database for future use in forensic and legal studies.     

RMplex reveals population differences in RM Y-STR mutation rates and provides improved father-son differentiation in Japanese

Rapidly mutating Y chromosomal short tandem repeat markers (RM Y-STRs) –characterized by at least one mutation per 100 generations– are suitable for differentiating both related and unrelated males. The recently introduced multiplex method RMplex allows for the efficient analysis of 30 Y-STRs with increased mutation rates, including all 26 currently known RM Y-STRs. While currently available RM Y-STR mutation rates were established mostly from European individuals, here we applied RMplex to DNA samples of 178 genetically confirmed father-son pairs from East Asia. For several Y-STRs, we found significantly higher mutation rates in Japanese compared to previous estimates. The consequent father-son differentiation rate based on RMplex was significantly higher (52%) in Japanese than previously reported for Europeans (42%), and much higher than with Yfiler Plus in both sample sets (14% and 13%, respectively). Further analysis suggests that the higher mutation and relative differentiation rates in Japanese can in part be explained by on average longer Y-STR alleles relative to Europeans. Moreover, we show that the most striking difference, which was found in DYS712, could be linked to a Y-SNP haplogroup (O1b2-P49) that is common in Japanese and rare in other populations. We encourage the forensic Y-STR community to generate more RMplex data from more population samples of sufficiently large sample size in combination with Y-SNP data to further investigate population effects on mutation and relative differentiation rates. Until more RMplex data from more populations become available, caution shall be placed when applying RM Y-STR mutation rate estimates established in one population, such as Europeans, to forensic casework involving male suspects of paternal origin from other populations, such as non-Europeans.     

Population genetic polymorphisms for 17 Y-chromosomal STRs haplotypes of Chinese Salar ethnic minority group

We studied and established a DNA database of 17 Y-STRs in a population sample of 133 unrelated individuals of Salar ethnic minority group, in order to investigate haplotype frequencies of Salar population, evaluate their usefulness in forensic applications, and enrich Chinese population genetic informational resources. Out of a total of 133 individuals 123 showed different haplotypes, while six haplotypes occurred more than once. The overall haplotype diversity for the Y-STRs loci was 0.9983, and the discrimination capacity was 0.9248.     

Development of the Kazakhstan Y-chromosome haplotype reference database: analysis of 27 Y-STR in Kazakh population

To improve available databases of forensic interest, all Y-STR haplotypes from Kazakh population were presented in this study. The reference database accumulated almost 3650 samples from academic and citizen science. Additionally, 27 Y-STR from Yfiler Plus System were first analyzed in 300 males from Kazakh (Qazaq) populations residing in Kazakhstan. The data is available in the YHDR under accession numbers YA004316 and YA004322. A total of 270 unique haplotypes were observed. Discrimination capacity was 90%. Obtained Y-STR haplotypes exhibited a high intra-population diversity. Analysis of pairwise genetic distances showed lowest R_ST values from Uighur and Mongolian populations.

     

Genetic diversity and phylogenetic analysis of 29 Y-STR loci in the Tibetan population from Sichuan Province,Southwest China

Y-Chromosomal short tandem repeat polymorphisms (Y-STRs) are widely applied in human forensic cases and population genetic studies. There is a lack of information about the Sichuan Tibetan population in the Y-STR Haplotype Reference Database (YHRD, https://yhrd.org, release 59). In this study, 502 unrelated male individuals residing in the Sichuan Province were recruited and genotyped at 29 Y-STR loci. A total of 479 haplotypes were observed, 460 (96.03%) of which were unique. The haplotype diversity (HD) and discrimination capacity (DC) for the Sichuan Tibetan population were 0.9998 and 0.9542, respectively. To reveal the genetic diversities and relationships between the Chinese Sichuan Tibetan and 29 other previously reported populations, forensic parameter analysis, multi-dimensional scaling, and phylogenetic reconstruction were performed. The results showed that the Sichuan Tibetan population was relatively isolated from other populations, suggesting that genetic proximity is in line with geographical boundaries.     

The impact of additional Y-STR loci on resolving common haplotypes and closely related individuals

Commercial Y-STR kits have permitted laboratories to go beyond the original nine minimal haplotype loci (MHL) and to discover the advantage of additional Y-STR loci in resolving common haplotypes. In an effort to examine the impact of Y-STR markers beyond the 17 loci now available in commercial kit form, new Y-STR loci are being investigated on a common set of samples representative of the major U.S. population groups. Additional Y-STRs can also increase the power of discrimination between closely related male individuals, which is important not only in forensics but also in the paternity and genetic genealogy communities.