Chromosome Y microsatellites: population genetic and evolutionary aspects

Mutation analysis for newly suggested 30 Y-STR loci with high mutation rates in Chinese father-son pairs

Rapidly mutating Y-STRs (RM Y-STRs) harbor great potential to distinguish male relatives and achieve male identification. However, forensic applications were greatly limited by the small number of the initially identified 14 RM Y-STRs. Recently, with the emergence of 12 novel RM Y-STRs, an integrated panel named RMplex was introduced, which contains all 26 RM Y-STRs and four fast mutating Y-STRs (FM Y-STRs). To obtain the first data on the mutation rates and father-son differentiation rates of the 30 newly proposed Y-STRs in Chinese populations, we performed an empirical mutation study on 307 DNA-confirmed Chinese paternal pairs. Previously reported mutation rates for 14 RM Y-STRs in Chinese and European populations were pooled and merged with our data. The highest meiosis number for the two groups reached 4771 and 2687, respectively. Five loci showed significant differences between the populations (DYS570, DYS399S1, DYS547, DYS612, and DYF403S1b). For the new panel covering 30 Y-STR loci, our results show extensive differences in the mutation rates between the two populations, as well. 10 RM Y-STR loci showed relatively low mutation rates (10^-3-10^-2 per meiosis) and 2 FM Y-STR loci had rapid mutation rates (> 10^-2 per meiosis) in the Chinese population. Several-fold differences in mutation rates were found in nine Y-STR loci between the Chinese and reference populations, with two loci having significantly higher mutation rates and one locus with a significantly lower mutation rate in the Chinese population (P < 0.05). Eighteen RM Y-STRs (> 10^-2 per meiosis), 8 FM Y-STR loci (5×10^-3-10^-2 per meiosis), 3 moderately mutating Y-STRs (MM Y-STRs, 10^-3-5×10^-3 per meiosis), and one locus with no observed mutation events were identified in the Chinese population. 40.06% of the Chinese paternity pairs were discriminated with RMplex while only 20.84% with the initial 14 RM Y-STRs, indicating that RMplex is beneficial for distinguishing paternally related males. Future studies on populations of different genetic backgrounds are necessary to obtain comprehensive estimates of mutation rates at these new loci.

On the Forensic Use of Y-Chromosome Polymorphisms

Nowadays, the use of Y-chromosome polymorphisms forms an essential part of many forensic DNA investigations. However, this was not always the case. Only since 1992 have we seen that some forensic scientists started to have an interest in this chromosome. In this review, I will sketch a brief history focusing on the forensic use of Y-chromosome polymorphisms. Before describing the various applications of short-tandem repeats (STRs) and single nucleotide polymorphisms (SNPs) on the Y-chromosome, I will discuss a few often ignored aspects influencing proper use and interpretation of Y-chromosome information: (i) genotyping Y-SNPs and Y-STRs, (ii) Y-STR haplotypes shared identical by state (IBS) or identical by descent (IBD), and (iii) Y-haplotype database frequencies.

Sequence Variations of 31 Υ-Chromosomal Short Tandem Repeats Analyzed by Massively Parallel Sequencing in Three U.S. Population Groups and Korean Population

BACKGROUND

Rapidly mutating (RM) Y-chromosomal short tandem repeats (Y-STRs) have been demonstrated to increase the possibility of distinguishing between male relatives due to a higher mutation rate than conventional Y-STRs. Massively parallel sequencing (MPS) can be useful for forensic DNA typing as it allows the detection of sequence variants of many forensic markers. Here, we present sequence variations of 31 Y-STRs including nine RM Y-STRs (DYF387S1, DYF399S1, DYF404S1, DYS449, DYS518, DYS570, DYS576, DYS612, and DYS627), their frequencies, distribution, and the gain in the number of alleles using MPS.

METHODS

We constructed a multiplex MPS assay capable of simultaneously amplifying 32 Y-chromosomal markers, producing amplicons ranging from 85-274 bp. Barcoded libraries from 220 unrelated males from four populations-African Americans, Caucasians, Hispanics, and Koreans-were generated via two-step polymerase chain reaction and sequenced on a MiSeq system. Genotype concordance between the capillary electrophoresis (CE) and MPS method and sequence variation of Y-STRs were investigated.

RESULTS

In total, 195 alleles were increased by MPS compared to CE-based alleles (261 to 456). The DYS518 marker showed the largest increase due to repeat region variation (a 3.69-fold increase). The highest increase in the number of alleles due to single nucleotide polymorphisms in the flanking region was found in DYF399S1. RM Y-STRs had more diverse sequences than conventional Y-STRs. Furthermore, null alleles were observed in DYS576 due to primer-binding site mutation, and allele drop-outs in DYS449 resulted from low marker coverage of less than the threshold.

CONCLUSION

The results suggest that the expanded and discriminative MPS assay could provide more genetic information for Y-STRs, especially for RM Y-STRs, and could advance male individualization. Compiling sequence-based Y-STR data for worldwide populations would facilitate the application of MPS in the field of forensic genetics and could be applicable in solving male-related forensic cases.

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.

HIV-1 Nucleic Acids Identify Rectal HIV Exposures in Self-Collected Rectal Swabs, Whereas Y-Chromosome Single Tandem Repeat Mixtures Are Not Reliable Biomarkers of Condomless Receptive Anal Intercourse

BACKGROUND

To focus interventions, biomarkers of HIV-1 exposure could help in identifying subpopulations at highest risk of acquisition. We assessed whether Y-chromosome single tandem repeat (YSTR) mixtures obtained from rectal swabs could serve as a biomarker of condomless receptive anal intercourse (CRAI) among men who have sex with men and transgender women and evaluated the feasibility of detecting HIV-1 virions to assess exposures.

METHODS

Twenty-nine sexually active HIV-seronegative men who have sex with men and one transgender woman from New York City answered on-site and mobile app sexual behavior questionnaires. They were randomized to collecting self-administered rectal swabs every morning or after receptive anal intercourse (RAI). YSTR profiles were assessed from blood sample and swabs; HIV-1 exposure was measured by conducting quantitative polymerase chain reaction in swabs.

RESULTS

After 2 months, the daily mobile survey had 135%-201% more instances of anal sex acts and 170%-193% more RAI than on-site surveys. Daily mobile reporting had 11%-35% less CRAI events than those reported on-site (Pdaily = 0.001; Pper-sex = 0.047). The daily swabbing arm reported less RAI (P < 0.001) and CRAI (P < 0.038) and had 2.95 lower odds of detecting YSTR mixtures (P = 0.021) than the per-sex-event arm. Surprisingly, YSTR detection was not significantly modified by report of bowel movements and lubricant, enema, or condom use. No participant became HIV-1 infected, yet HIV-1 total nucleic acids were detected in 6 independent episodes of CRAI in 2 participants taking pre-exposure prophylaxis.

CONCLUSIONS

YSTR mixtures demonstrated 80% specificity but only 30% sensitivity as a biomarker of CRAI in self-collected rectal swabs. However, detection of HIV-1 exposures in self-collected swabs may help in identifying those needing further HIV risk reduction strategies.

Forensic investigation of war graves from WWI and WWII in Hungary

The Hungarian war grave care professionals weren't in an easy situation when they started the work because, until 2012, the burial places of Hungarian soldiers had no legal protection. It was necessary to develop legal regulations and scientific methods. Since this is a multidisciplinary field, the work is quite compound as many professionals from different field of sciences work together. This work requires the harmonic work of military historians, archaeologists, anthropologists and geneticists. Thanks to the conscientious work of these professionals, nowadays, we can talk about a stable institutionalized, multidisciplinary war grave care in Hungary which encompasses the work of the above-mentioned professionals. Thanks to scientific development, new opportunities are available for the professionals to identify war heroic deads. In this article, the history and the formation of the Hungarian war grave care are introduced and the methodology of the Hungarian war grave care professionals work is shown. The paper also aims to illustrate the changes in laws and the standard practice currently followed by professionals during the exploration and the processing of the human remains.

Mining the red deer genome (CerEla1.0) to develop X-and Y-chromosome-linked STR markers

Microsatellites are widely applied in population and forensic genetics, wildlife studies and parentage testing in animal breeding, among others, and recently, high-throughput sequencing technologies have greatly facilitated the identification of microsatellite markers. In this study the genomic data of Cervus elaphus (CerEla1.0) was exploited, in order to identify microsatellite loci along the red deer genome and for designing the cognate primers. The bioinformatics pipeline identified 982,433 microsatellite motifs genome-wide, assorted along the chromosomes, from which 45,711 loci mapped to the X- and 1096 to the Y-chromosome. Primers were successfully designed for 170,873 loci, and validated with an independently developed autosomal tetranucleotide STR set. Ten X- and five Y-chromosome-linked microsatellites were selected and tested by two multiplex PCR setups on genomic DNA samples of 123 red deer stags. The average number of alleles per locus was 3.3, and the average gene diversity value of the markers was 0.270. The overall observed and expected heterozygosities were 0.755 and 0.832, respectively. Polymorphic Information Content (PIC) ranged between 0.469 and 0.909 per locus with a mean value of 0.813. Using the X- and Y-chromosome linked markers 19 different Y-chromosome and 72 X-chromosome lines were identified. Both the X- and the Y-haplotypes split to two distinct clades each. The Y-chromosome clades correlated strongly with the geographic origin of the haplotypes of the samples. Segregation and admixture of subpopulations were demonstrated by the use of the combination of nine autosomal and 16 sex chromosomal STRs concerning southwestern and northeastern Hungary. In conclusion, the approach demonstrated here is a very efficient method for developing microsatellite markers for species with available genomic sequence data, as well as for their use in individual identifications and in population genetics studies.

27 Y-chromosomal STR haplotypic structure for the Chinese Han population from Changchun, Northeastern China

Y- Changchun is the capital and largest city of Jilin Province in the northeast China. In this study, we genotyped and investigated haplotypes of 27 Y-STR loci in 1037 Changchun Han male individuals using commercially available AmpFlSTR Yfiler® Plus kit. We calculated the Gene diversity (GD) values and haplotype diversity (HD) as important forensic parameters. Furthermore, we observed genetic affinities between Changchun Han with other Northern Han Chinese populations and also Korans in Yanbian in the Multidimensional scaling and phylogenetic tree analysis.

The Y Chromosome: A Complex Locus for Genetic Analyses of Complex Human Traits

The Human Y chromosome (ChrY) has been demonstrated to be a powerful tool for phylogenetics, population genetics, genetic genealogy and forensics. However, the importance of ChrY genetic variation in relation to human complex traits is less clear. In this review, we summarise existing evidence about the inherent complexities of ChrY variation and their use in association studies of human complex traits. We present and discuss the specific particularities of ChrY genetic variation, including Y chromosomal haplogroups, that need to be considered in the design and interpretation of genetic epidemiological studies involving ChrY.

Geographical structuring and low diversity of paternal lineages in Bahrain shown by analysis of 27 Y-STRs

We have determined the distribution of Y-chromosomal haplotypes and predicted haplogroups in the ethnically diverse Kingdom of Bahrain, a small archipelago in the Arabian Gulf. Paternal population structure within Bahrain was investigated using the 27 Y-STRs (short tandem repeats) in the Yfiler Plus kit to generate haplotypes from 562 unrelated Bahraini males, sub-divided into four geographical regions—Northern, Capital, Southern and Muharraq. Yfiler Plus provided a significant improvement over the 17-locus Yfiler kit in discrimination capacity (from 77% to 87.5% overall), but discrimination capacity differed widely between regions from 98.4% in Muharraq to 75.2% in the Northern region, an unusually low value possibly resulting from recent rapid population expansion. Clusters of closely related male lineages were seen, with only 79.4% of donors displaying unique haplotypes and 59% of instances of shared haplotypes occurring within, rather than between, regions. Haplogroup prediction indicated diverse origins of the population with a predominance of haplogroups J2 and J1, both typical of the Arabian Peninsula, but also haplogroups such as B2 and E1b1a likely originating in Africa, and H, L and R2 likely indicative of migration from South Asia. Haplogroup frequencies differed significantly between regions, with J2 significantly more common in the Northern region compared with the Southern, possibly due to differential settlement by Baharna and Arabs. Our study shows that paternal lineage population structure can exist even over small geographical scales, and that highly discriminating genetic tools are required where rapid expansions have occurred within tightly bounded populations.

Rapidly mutating Y-STRs study in Chinese Yi population

Y-chromosomal short tandem repeats (Y-STRs) have been widely used in forensic analysis and population genetics. With low to moderate mutation rates, conventional Y-STR panels, including commercially available Y-STR kits, enable the identification of male pedigrees but typically fail to differentiate related male individuals. The introduction of rapidly mutating Y-chromosomal short tandem repeats (RM Y-STRs) with higher mutation rates (μ > 10^-2) has been demonstrated to increase the discrimination capacity of unrelated men and the differentiation rate of related men compared with standard Y-STRs. To date, several studies have been performed worldwide. Here, 260 father-son pairs from Chinese Yi population were investigated, and 18.8% of them were differentiated with the 13 RM Y-STR markers, which was close to the theoretical estimate of 19.5% based on the mutation rates of these markers. Among the 57 mutations observed, repeat gains were more common than repeat losses (1.48:1), and one-step mutations were more common than two-step mutations (27.5:1). Locus-specific mutation rates ranged from < 3.85 × 10^-3 (95% CI 0.00-1.41 × 10^-2) to 3.85 × 10^-2 (95% CI 1.86 × 10^-2-6.96 × 10^-2), with an average mutation rate of 1.46 × 10^-2 (95% CI 1.11 × 10^-2-1.89 × 10^-2). Furthermore, we combined the father-son pair data from the present study with the data from the previous studies, generating an overall mutation rate of 1.70 × 10^-2. The high differentiation rate obtained in the present study indicates the suitability of RM Y-STRs to distinguish paternal lineages in Chinese Yi population.

A forensic multiplex of nine novel pentameric-repeat STRs

Pentameric-repeat short tandem repeats (STRs), consisting of loci with repeat units of five base-pairs, have the advantage of reduced stutter products compared to their tetrameric-repeat STR counterparts. This characteristic potentially helps the interpretation of mixed DNA profiles when minor component alleles may coincide with stutter peaks from the major components. To develop a simple but informative forensic multiplex with the capability to aid mixture interpretation, we designed an 11-plex assay of nine pentameric STRs new to forensic analysis plus two male- specific markers: DYS391 and the Y-Indel rs2032678 used in GlobalFiler™ (Life Technologies). East Asian-specific variation in the recently adopted Y-Indel rs2032678 is reported in this study for the first time in its forensic use as a sex marker. We estimated the levels of variation observed in the nine pentameric STRs in three of the major population groups sampled in the HGDP-CEPH human genome diversity panel: African, European and East Asian (combining individual populations as their sample sizes were too small for STR allele frequency estimations); and we include genotype data from a population sample of Northwest Spain. From this data, forensic informativeness metrics were estimated when applying the nine novel STRs in identification or kinship analyses. The assay was assessed for forensic sensitivity and ability to successfully genotype highly degraded DNA. In the profiles from the 11-plex assay we observed an average 2.15% stutter ratio in all the pentameric loci compared to 7.32% across equivalently-sized tetrameric STRs in the Promega Powerplex^® ESX-17 kit.

Detecting past male-mediated expansions using the Y chromosome

Males and females display biological differences that lead to a higher variance of offspring number in males, and this is frequently exacerbated in human societies by mating practices, and possibly by past socio-cultural circumstances. This implies that the genetic record might contain the imprint of past male-mediated expansions, which can be investigated by analysing the male-specific region of the Y chromosome (MSY). Here, we review studies that have used MSY data to infer such expansions. Sets of short-tandem repeats define haplotypes of very low average frequencies, but in a few cases, high-frequency haplotypes are observed, forming the core of descent clusters. Estimates of the ages of such clusters, together with geographical information, have been used to propose powerful historical founders, including Genghis Khan, although without direct supporting evidence. Resequencing of multi-megabase segments of MSY has allowed the construction of detailed phylogenies in which branch lengths are proportional to time, leading to the identification of lineage expansions in the last few millennia as well as the more distant past. Comparisons with maternally-inherited mitochondrial DNA sequence data allow the male specificity of some of these expansions to be demonstrated. These include expansions in Europe in the last ~5000 years that may be associated with a cultural shift during the Bronze Age, as well as expansions elsewhere in the world for which explanations from archaeological evidence are not yet clear.

Forensic use of Y-chromosome DNA: a general overview

The male-specific part of the human Y chromosome is widely used in forensic DNA analysis, particularly in cases where standard autosomal DNA profiling is not informative. A Y-chromosomal gene fragment is applied for inferring the biological sex of a crime scene trace donor. Haplotypes composed of Y-chromosomal short tandem repeat polymorphisms (Y-STRs) are used to characterise paternal lineages of unknown male trace donors, especially suitable when males and females have contributed to the same trace, such as in sexual assault cases. Y-STR haplotyping applied in crime scene investigation can (i) exclude male suspects from involvement in crime, (ii) identify the paternal lineage of male perpetrators, (iii) highlight multiple male contributors to a trace, and (iv) provide investigative leads for finding unknown male perpetrators. Y-STR haplotype analysis is employed in paternity disputes of male offspring and other types of paternal kinship testing, including historical cases, as well as in special cases of missing person and disaster victim identification involving men. Y-chromosome polymorphisms are applied for inferring the paternal bio-geographic ancestry of unknown trace donors or missing persons, in cases where autosomal DNA profiling is uninformative. In this overview, all different forensic applications of Y-chromosome DNA are described. To illustrate the necessity of forensic Y-chromosome analysis, the investigation of a prominent murder case is described, which initiated two changes in national forensic DNA legislation both covering Y-chromosome use, and was finally solved via an innovative Y-STR dragnet involving thousands of volunteers after 14 years. Finally, expectations for the future of forensic Y-chromosome DNA analysis are discussed.

Developmental Validation of a novel 5 dye Y-STR System comprising the 27 YfilerPlus loci

In this study, a new STRtyper-27 system, including the same Yfiler Plus loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385a/b, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, Y-GATA H4, DYS449, DYS460, DYS481, DYS518, DYS533, DYS570, DYS576, DYS627 and DYF387S1a/b), was established using a set of 5 fluorescent dye labels. Primers, internal size standard, allelic ladders and matrix standard set were designed and created in-house for this multiplex system. This paper describes the validation studies conducted with the STRtyper-27Y system using a 3130XL genetic analyzer for fragment length detection that included the analysis of the following parameters and aspects: sensitivity, species specificity, inhibition, haplotype concordance, precision, stutter, DNA mixtures, and stability studies with crime scene samples. The studies demonstrated, that the STRtyper-27Y system provided equivalent overall performance comparable to the latest Yfiler Plus kit, but with enhanced compatibility in terms of instrument platforms and software allowing forensic laboratories to conduct its forensic application and evaluate its performance, all in their own 5 dye Y-STR chemistry system /environment without software or instrument upgrades.

Haplotype data of 23 Y-chromosome markers in Minnan Han Chinese and comparison with those of 12 Y-chromosome markers

We genotyped 23 Y-STR loci (DYS576, DYS389I, DYS448, DYS389II, DYS19, DYS391, DYS481, DYS549, DYS533, DYS438, DYS437, DYS570, DYS635, DYS390, DYS439, DYS392, DYS643, DYS393, DYS458, DYS385a/b, DYS456, and GATA-H4) in a sample of 109 unrelated male Chinese people residing in Minnan area and compared the results with those from our previous study on 12 Y-STR. The haplotype diversity and the discrimination capacity of the 23 Y-STR reached 0.9903 and 0.9725, respectively, and the genetic diversity for each locus ranged from 0.321 (DYS391) to 0.955 (DYS385). Besides, we observed a strong correlation between the number of Y-STR markers and the substantial improvement of forensic parameters used to discriminate between individuals. The results indicated that these highly polymorphic Y-STR markers were useful for human identification in forensic cases and paternity tests within the Minnan Han Chinese population.

Paleo-Balkan and Slavic contributions to the genetic pool of Moldavians: insights from the Y chromosome

Moldova has a rich historical and cultural heritage, which may be reflected in the current genetic makeup of its population. To date, no comprehensive studies exist about the population genetic structure of modern Moldavians. To bridge this gap with respect to paternal lineages, we analyzed 37 binary and 17 multiallelic (STRs) polymorphisms on the non-recombining portion of the Y chromosome in 125 Moldavian males. In addition, 53 Ukrainians from eastern Moldova and 54 Romanians from the neighboring eastern Romania were typed using the same set of markers. In Moldavians, 19 Y chromosome haplogroups were identified, the most common being I-M423 (20.8%), R-M17* (17.6%), R-M458 (12.8%), E-v13 (8.8%), R-M269* and R-M412* (both 7.2%). In Romanians, 14 haplogroups were found including I-M423 (40.7%), R-M17* (16.7%), R-M405 (7.4%), E-v13 and R-M412* (both 5.6%). In Ukrainians, 13 haplogroups were identified including R-M17 (34.0%), I-M423 (20.8%), R-M269* (9.4%), N-M178, R-M458 and R-M73 (each 5.7%). Our results show that a significant majority of the Moldavian paternal gene pool belongs to eastern/central European and Balkan/eastern Mediterranean Y lineages. Phylogenetic and AMOVA analyses based on Y-STR loci also revealed that Moldavians are close to both eastern/central European and Balkan-Carpathian populations. The data correlate well with historical accounts and geographical location of the region and thus allow to hypothesize that extant Moldavian paternal genetic lineages arose from extensive recent admixture between genetically autochthonous populations of the Balkan-Carpathian zone and neighboring Slavic groups.

Distinguishing the co-ancestries of haplogroup G Y-chromosomes in the populations of Europe and the Caucasus

Haplogroup G, together with J2 clades, has been associated with the spread of agriculture, especially in the European context. However, interpretations based on simple haplogroup frequency clines do not recognize underlying patterns of genetic diversification. Although progress has been recently made in resolving the haplogroup G phylogeny, a comprehensive survey of the geographic distribution patterns of the significant sub-clades of this haplogroup has not been conducted yet. Here we present the haplogroup frequency distribution and STR variation of 16 informative G sub-clades by evaluating 1472 haplogroup G chromosomes belonging to 98 populations ranging from Europe to Pakistan. Although no basal G-M201* chromosomes were detected in our data set, the homeland of this haplogroup has been estimated to be somewhere nearby eastern Anatolia, Armenia or western Iran, the only areas characterized by the co-presence of deep basal branches as well as the occurrence of high sub-haplogroup diversity. The P303 SNP defines the most frequent and widespread G sub-haplogroup. However, its sub-clades have more localized distribution with the U1-defined branch largely restricted to Near/Middle Eastern and the Caucasus, whereas L497 lineages essentially occur in Europe where they likely originated. In contrast, the only U1 representative in Europe is the G-M527 lineage whose distribution pattern is consistent with regions of Greek colonization. No clinal patterns were detected suggesting that the distributions are rather indicative of isolation by distance and demographic complexities.

Haplotype analysis of the polymorphic 17 YSTR markers in Kerala nontribal populations

The origin of the Kerala non tribal population has been a matter of contention for centuries. While some claim that Negritos were the first inhabitants, some historians suggest a Dravidian origin for all Keralites. The aim of our study has been to provide sufficient scientific evidence based on Y chromosome short tandem repeat (Y STR) analysis for tracing the paternal lineage and also to create a database of the Y STR haplotype of the male population for future forensic analysis. Whole blood samples (n = 168) were collected from unrelated healthy men of the Kerala non-tribal population over a period of 2 years from October 2009. Genomic DNA was extracted by salting out method. All samples were genotyped for the 17 Y STR loci by the AmpFLSTR Y-filer PCR Amplification Kit. The haplotype and allele frequencies were determined by direct counting and analyzed using Arlequin 3.1 software, and molecular variance was calculated with the Y chromosome haplotype reference database online analysis tool, www.yhrd.org . Haplotype diversity was calculated using HaPYDive ( http://portugene.com/hapydive.html ). The majority of haplotypes were unique (149/168). The variant allele 17.1 was observed in DYS 385 loci in three samples. Fifteen samples (8.93%) showed the presence of alleles that are not within the established marker range denoted as outside marker range (OMR). The allele frequency of Kerala non tribal population ranged from 0.00003 to 0.5809. The most polymorphic single locus marker was DYS 458. The haplotype diversity value for Kerala non tribal population was 0.9978. The pairwise difference value ranged from 0.0531 to 0.0854 on comparison of the haplotypes of the Kerala non tribals with other Indian populations. The multi dimensional scaling plot depicted the proximity of Kerala non tribal population with Vasterbotten population (Swedish) and Paiwan, Patyal population of Taiwan, Thailand, and Zhuang population of China. The results of the study indicate towards a European paternal lineage in the non tribal Kerala population.

Y-short tandem repeat haplotype and paternal lineage of the Ezhava population of Kerala, south India

AIM

To analyze the haplotype of the Ezhava population of Kerala, south India, using 8 short tandem repeat (STR) loci on the Y chromosome and trace the paternal genetic lineage of the population.

METHODS

Whole blood samples (n=104) were collected from unrelated healthy men of the Ezhava population over a period of one year from October 2009. Genomic DNA was extracted by salting out method. All samples were genotyped for the 8 Y-STR loci by the AmpFiSTR Y-filer PCR Amplification Kit. The haplotype and allele frequencies were determined by direct counting and analyzed using Arlequin 3.1 software, and molecular variance was calculated with the Y-chromosome haplotype reference database online analysis tool, www.yhrd.org.

RESULTS

Among the 104 examined haplotypes, we found 98 unique ones. The average gene diversity was 0.669, with the highest diversity of 0.9462 observed for the biallelic Y-STR marker DYS 385. The allele frequency among DYS loci varied between 0.0096 and 0.75. Out of the 104 haplotypes, 10 were identical to the Jat Sikh population of Punjab, which is the greatest number among the Indian populations, and 4 to the Turkish population, which is the greatest number among the European populations. According to the allele frequency of Y-STR, the Ezhavas were genetically more similar to the Europeans (60%) than to the East Asians (40%).

CONCLUSION

The vast majority of haplotypes were observed only once, reflecting the enormous genetic heterogeneity of the Ezhavas. Based on the genotype, the Ezhavas showed more resemblance to Jat Sikh population of Punjab and the Turkish populations than to the East Asians, hence indicating a paternal lineage of European origin.

[Polymorphism of 17 Y-STR loci in Shanxi Han population and genetic relationship with 13 populations]

To investigate the genetic polymorphisms of 17 Y-chromosomal short tandem repeats (Y-STR) loci in Shanxi Han population and to explore their forensic application values and genetic relationship with neighboring populations, 17 Y-STR in 222 unrelated healthy Shanxi Han individuals were amplified with Y-filerTM System, and the PCR products were detected with 3130 Genetic Aanalyzer. The allele frequencies and haplotype diversity were calculated. Y-STR data of another 13 populations were collected from publications. Cluster analysis and phylogenic trees were applied to show the genetic distance among the populations. As a result, a total of 219 haplotypes were identified, and the observed haplotypes diversity value was 0.9999. The gene diversity values (GD) for each locus ranged from 0.3894 (DYS391) to 0.9755 (DYS385a/b). Comparing with 13 populations, the genetic distance between Shanxi and Jihei Han populations was the smallest (0.0001), while the genetic distance between Shanxi and Taiwan population was the largest (0.0152). The phylogenetic tree was similar to the results of clustering analysis. Multiplex detection of the 17 Y-STR loci revealed a highly polymorphic genetic distribution, which would be very powerful for establishing a Y-STR database, for population genetics and forensic practice.

Characterization of Y-chromosomal short tandem repeat markers in Pakistani populations

The Y chromosome microsatellite markers have been extensively used for population genetic studies and in individual identification and paternity testing in forensic medicine. In the present study, we report the data of five male-specific, polymorphic microsatellites in 740 unrelated male individuals from 12 different ethnic groups of Pakistan. The overall diversities of these individual loci in Pakistan ranged from 0.236 to 0.799. The total haplotypes identified were 152, and of these, 70 different haplotypes were present in only single individuals. Two haplotypes were found more frequently, 9_8_17_11_24 (13.5%) and 9_8_17_11_25 (8.6%), showing population-specific clustering in the Mohanna and the Brahui, respectively. An overall haplotype diversity of 0.965 in Pakistan suggested a high power of discrimination for these loci. Few populations, particularly the Mohanna and the Balti, showed lower haplotype diversity values for these loci (0.662 and 0.758, respectively). This set of microsatellite loci reported in the study can be used for population genetics and forensic medicine analysis. This study also demonstrates the importance of studying haplotype distribution pattern in population genetics.

Diversity of five novel Y-STR loci and their application in studies of north Chinese populations

Y-chromosomal short tandem repeats (Y-STRs) show sufficient variability among individuals in a population and high degree of geographical differentiation, so their polymorphic character makes them especially suited for population genetic studies. In this study, five novel Y-STR loci were analysed in 174 samples from five minority populations residing in north China (Daur, Kazak, Xibe, Uighur and Kirgiz) to determine the diversity of these loci in north China and to evaluate their usefulness in population study. Ninety-seven haplotypes were constructed, with 30 in Daur, 24 in Kazak, 28 in Uighur, 27 in Xibe and 16 in Kirgiz. Sixty-six (68.04%) of them were unique. The R(ST) showed that there was no significant difference in Daur and Xibe (R(ST) = 0.02231, P > 0.05), while among the Kazak, Uighur and Kirgiz, who reside in northwest China, there were significant differences. These results showed that these five Y-STR loci were polymorphic in the five populations. The results of AMOVA showed that majority of the differences were found within populations. By RST, the relationships of the five populations were accordance with the historical records: Xibe migrated to Xinjiang during the Qing dynasty, and Kazak, Uighur and Kirgiz have different ancestors.

Brief communication: Restricted geographic distribution for Y-Q* paragroup in South America

We analyzed 21 paragroup Q* Y chromosomes from South American aboriginal and urban populations. Our aims were to evaluate the phylogenetic status, geographic distribution, and genetic diversity in these groups of chromosomes and compare the degree of genetic variation in relation to Q1a3a haplotypes. All Q* chromosomes from our series and five samples from North American Q* presented the derivate state for M346, that is present upstream to M3, and determined Q1a3* paragroup. We found a restrictive geographic distribution and low frequency of Q1a3* in South America. We assumed that this low frequency could be reflecting extreme drift effects. However, several estimates of gene diversity do not support the existence of a severe bottleneck. The mean haplotype diversity expected was similar to that for South American Q1a3* and Q1a3a (0.478 and 0.501, respectively). The analysis of previous reports from other research groups and this study shows the highest frequencies of Q* for the West Corner and the Grand Chaco regions of South America. At present, there is no information on whether the phylogenetic status of Q* paragoup described in previous reports is similar to that of Q1a3* paragroup though our results support this possibility.