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Y chromosome short tandem repeats (Y-STRs) are commonly used to identify male lineages for investigative and judicial purposes and could represent the only source of male-specific genetic information from unbalanced female-male mixtures. The Yfiler Plus multiplex, which includes twenty conventional and seven rapidly-mutating Y-STRs, represents the most discriminating patrilineal system commercially available to date. Over the past five years, this multiplex has been used to analyze several Eurasian populations, with a reported discrimination capacity (DC) approaching or corresponding to the highest possible value. However, despite the inclusion of rapidly mutating Y-STRs, extensive haplotype sharing was still reported for some African populations due to a number of different factors affecting the effective population size. In the present study, we analyzed 27 Y-STRs included in the Yfiler Plus multiplex and 82 Y-SNPs in central Sahel (northern Cameroon and western Chad), an African region characterized by a strong ethnic fragmentation and linguistic diversity. We evaluated the effects of population sub-structuring on genetic diversity by stratifying a sample composed of 431 males according to their ethnicity (44 different ethnic groups) and urbanization degree (four villages and four towns). Overall, we observed a low discrimination capacity (DC = 0.90), with 71 subjects (16.5 %) sharing 27 Y-STR haplotypes. Haplotype sharing was essentially limited to subjects with the same binary haplogroup, coming from the same location and belonging to the same ethnic group. Haplotype sharing was much higher in rural areas (average DC = 0.83) than urban settlements (average DC = 0.96) with a significant correlation between DC and census size (r = 0.89; p = 0.003). Notably, we found that genetic differentiation between villages from the same country (Φ ST  = 0.14) largely exceeded that found among countries (Φ ST  = 0.02). These findings have important implications for the choice of the appropriate reference population database to evaluate the statistical relevance of forensic Y-haplotype matches., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Recent genome studies of modern and ancient samples have proposed that Native Americans derive from a subset of the Eurasian gene pool carried to America by an ancestral Beringian population, from which two well-differentiated components originated and subsequently mixed in different proportion during their spread in the Americas. To assess the timing, places of origin and extent of admixture between these components, we performed an analysis of the Y-chromosome haplogroup Q, which is the only Pan-American haplogroup and accounts for virtually all Native American Y chromosomes in Mesoamerica and South America., Results: Our analyses of 1.5 Mb of 152 Y chromosomes, 34 re-sequenced in this work, support a "coastal and inland routes scenario" for the first entrance of modern humans in North America. We show a major phase of male population growth in the Americas after 15 thousand years ago (kya), followed by a period of constant population size from 8 to 3 kya, after which a secondary sign of growth was registered. The estimated dates of the first expansion in Mesoamerica and the Isthmo-Colombian Area, mainly revealed by haplogroup Q-Z780, suggest an entrance in South America prior to 15 kya. During the global constant population size phase, local South American hints of growth were registered by different Q-M848 sub-clades. These expansion events, which started during the Holocene with the improvement of climatic conditions, can be ascribed to multiple cultural changes rather than a steady population growth and a single cohesive culture diffusion as it occurred in Europe., Conclusions: We established and dated a detailed haplogroup Q phylogeny that provides new insights into the geographic distribution of its Eurasian and American branches in modern and ancient samples.

Haplogroup E, defined by mutation M40, is the most common human Y chromosome clade within Africa. To increase the level of resolution of haplogroup E, we disclosed the phylogenetic relationships among 729 mutations found in 33 haplogroup DE Y-chromosomes sequenced at high coverage in previous studies. Additionally, we dissected the E-M35 subclade by genotyping 62 informative markers in 5,222 samples from 118 worldwide populations. The phylogeny of haplogroup E showed novel features compared with the previous topology, including a new basal dichotomy. Within haplogroup E-M35, we resolved all the previously known polytomies and assigned all the E-M35* chromosomes to five new different clades, all belonging to a newly identified subhaplogroup (E-V1515), which accounts for almost half of the E-M35 chromosomes from the Horn of Africa. Moreover, using a Bayesian phylogeographic analysis and a single nucleotide polymorphism-based approach we localized and dated the origin of this new lineage in the northern part of the Horn, about 12 ka. Time frames, phylogenetic structuring, and sociogeographic distribution of E-V1515 and its subclades are consistent with a multistep demic spread of pastoralism within north-eastern Africa and its subsequent diffusion to subequatorial areas. In addition, our results increase the discriminative power of the E-M35 haplogroup for use in forensic genetics through the identification of new ancestry-informative markers., (© The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

One hundred and forty-six previously detected mutations were more precisely positioned in the human Y chromosome phylogeny by the analysis of 51 representative Y chromosome haplogroups and the use of 59 mutations from literature. Twenty-two new mutations were also described and incorporated in the revised phylogeny. This analysis made it possible to identify new haplogroups and to resolve a deep trifurcation within haplogroup B2. Our data provide a highly resolved branching in the African-specific portion of the Y tree and support the hypothesis of an origin in the north-western quadrant of the African continent for the human MSY diversity.

Haplogroup E1b1, defined by the marker P2, is the most represented human Y chromosome haplogroup in Africa. A phylogenetic tree showing the internal structure of this haplogroup was published in 2008. A high degree of internal diversity characterizes this haplogroup, as well as the presence of a set of chromosomes undefined on the basis of a derived character. Here we make an effort to update the phylogeny of this highly diverse haplogroup by including seven mutations which have been newly discovered by direct resequencing. We also try to incorporate five previously-described markers which were not, however, reported in the 2008 tree. Additionally, during the process of mapping, we found that two previously reported SNPs required a new position on the tree. There are three key changes compared to the 2008 phylogeny. Firstly, haplogroup E-M2 (former E1b1a) and haplogroup E-M329 (former E1b1c) are now united by the mutations V38 and V100, reducing the number of E1b1 basal branches to two. The new topology of the tree has important implications concerning the origin of haplogroup E1b1. Secondly, within E1b1b1 (E-M35), two haplogroups (E-V68 and E-V257) show similar phylogenetic and geographic structure, pointing to a genetic bridge between southern European and northern African Y chromosomes. Thirdly, most of the E1b1b1* (E-M35*) paragroup chromosomes are now marked by defining mutations, thus increasing the discriminative power of the haplogroup for use in human evolution and forensics.

Although human Y chromosomes belonging to haplogroup R1b are quite rare in Africa, being found mainly in Asia and Europe, a group of chromosomes within the paragroup R-P25(*) are found concentrated in the central-western part of the African continent, where they can be detected at frequencies as high as 95%. Phylogenetic evidence and coalescence time estimates suggest that R-P25(*) chromosomes (or their phylogenetic ancestor) may have been carried to Africa by an Asia-to-Africa back migration in prehistoric times. Here, we describe six new mutations that define the relationships among the African R-P25(*) Y chromosomes and between these African chromosomes and earlier reported R-P25 Eurasian sub-lineages. The incorporation of these new mutations into a phylogeny of the R1b haplogroup led to the identification of a new clade (R1b1a or R-V88) encompassing all the African R-P25(*) and about half of the few European/west Asian R-P25(*) chromosomes. A worldwide phylogeographic analysis of the R1b haplogroup provided strong support to the Asia-to-Africa back-migration hypothesis. The analysis of the distribution of the R-V88 haplogroup in >1800 males from 69 African populations revealed a striking genetic contiguity between the Chadic-speaking peoples from the central Sahel and several other Afroasiatic-speaking groups from North Africa. The R-V88 coalescence time was estimated at 9.2-5.6 [corrected] kya, in the early mid Holocene. We suggest that R-V88 is a paternal genetic record of the proposed mid-Holocene migration of proto-Chadic Afroasiatic speakers through the Central Sahara into the Lake Chad Basin, and geomorphological evidence is consistent with this view.

Detailed population data were obtained on the distribution of novel biallelic markers that finely dissect the human Y-chromosome haplogroup E-M78. Among 6,501 Y chromosomes sampled in 81 human populations worldwide, we found 517 E-M78 chromosomes and assigned them to 10 subhaplogroups. Eleven microsatellite loci were used to further evaluate subhaplogroup internal diversification. The geographic and quantitative analyses of haplogroup and microsatellite diversity is strongly suggestive of a northeastern African origin of E-M78, with a corridor for bidirectional migrations between northeastern and eastern Africa (at least 2 episodes between 23.9-17.3 ky and 18.0-5.9 ky ago), trans-Mediterranean migrations directly from northern Africa to Europe (mainly in the last 13.0 ky), and flow from northeastern Africa to western Asia between 20.0 and 6.8 ky ago. A single clade within E-M78 (E-V13) highlights a range expansion in the Bronze Age of southeastern Europe, which is also detected by haplogroup J-M12. Phylogeography pattern of molecular radiation and coalescence estimates for both haplogroups are similar and reveal that the genetic landscape of this region is, to a large extent, the consequence of a recent population growth in situ rather than the result of a mere flow of western Asian migrants in the early Neolithic. Our results not only provide a refinement of previous evolutionary hypotheses but also well-defined time frames for past human movements both in northern/eastern Africa and western Eurasia.

Sequencing of 81 entire human mitochondrial DNAs (mtDNAs) belonging to haplogroups M1 and U6 reveals that these predominantly North African clades arose in southwestern Asia and moved together to Africa about 40,000 to 45,000 years ago. Their arrival temporally overlaps with the event(s) that led to the peopling of Europe by modern humans and was most likely the result of the same change in climate conditions that allowed humans to enter the Levant, opening the way to the colonization of both Europe and North Africa. Thus, the early Upper Palaeolithic population(s) carrying M1 and U6 did not return to Africa along the southern coastal route of the "out of Africa" exit, but from the Mediterranean area; and the North African Dabban and European Aurignacian industries derived from a common Levantine source.

The human Y chromosome haplogroup E-M78 (E3b1a) occurs commonly and is distributed in northern and eastern Africa, western Asia, and all of Europe. Previously, only two rarely observed internal biallelic markers (UEPs) were known within the E-M78 clade. Here we report the identification of six novel UEPs that significantly refine the phylogeny of this haplogroup. Then, we evaluate the correspondence between the newly defined sub-haplogroups and the E-M78 haplotype clusters previously identified by an 11-microsatellite loci-based network encompassing 232 chromosomes (Cruciani et al., 2004). We observed considerable correspondence between the trees generated by the two types of markers, but also noted important discrepancies between microsatellite and UEP findings. Overall, this analysis reveals that the currently visible terminal branches of the Y tree still contain a large amount of information, in terms of undiscovered biallelic markers, and that caution is needed when using the microsatellite alleles as surrogates of unique event polymorphisms.

Complete sequencing of 62 mitochondrial DNAs (mtDNAs) belonging (or very closely related) to haplogroup H revealed that this mtDNA haplogroup--by far the most common in Europe--is subdivided into numerous subhaplogroups, with at least 15 of them (H1-H15) identifiable by characteristic mutations. All the haplogroup H mtDNAs found in 5,743 subjects from 43 populations were then screened for diagnostic markers of subhaplogroups H1 and H3. This survey showed that both subhaplogroups display frequency peaks, centered in Iberia and surrounding areas, with distributions declining toward the northeast and southeast--a pattern extremely similar to that previously reported for mtDNA haplogroup V. Furthermore, the coalescence ages of H1 and H3 (~11,000 years) are close to that previously reported for V. These findings have major implications for the origin of Europeans, since they attest that the Franco-Cantabrian refuge area was indeed the source of late-glacial expansions of hunter-gatherers that repopulated much of Central and Northern Europe from ~15,000 years ago. This has also some implications for disease studies. For instance, the high occurrence of H1 and H3 in Iberia led us to re-evaluate the haplogroup distribution in 50 Spanish families affected by nonsyndromic sensorineural deafness due to the A1555G mutation. The survey revealed that the previously reported excess of H among these families is caused entirely by H3 and is due to a major, probably nonrecent, founder event.

We explored the phylogeography of human Y-chromosomal haplogroup E3b by analyzing 3401 individuals from five continents. Our data refine the phylogeny of the entire haplogroup, which appears as a collection of lineages with very different evolutionary histories, and reveal signatures of several distinct processes of migrations and/or recurrent gene flow that occurred in Africa and western Eurasia over the past 25000 years. In Europe, the overall frequency pattern of haplogroup E-M78 does not support the hypothesis of a uniform spread of people from a single parental Near Eastern population. The distribution of E-M81 chromosomes in Africa closely matches the present area of distribution of Berber-speaking populations on the continent, suggesting a close haplogroup-ethnic group parallelism. E-M34 chromosomes were more likely introduced in Ethiopia from the Near East. In conclusion, the present study shows that earlier work based on fewer Y-chromosome markers led to rather simple historical interpretations and highlights the fact that many population-genetic analyses are not robust to a poorly resolved phylogeny.

The variation of 77 biallelic sites located in the nonrecombining portion of the Y chromosome was examined in 608 male subjects from 22 African populations. This survey revealed a total of 37 binary haplotypes, which were combined with microsatellite polymorphism data to evaluate internal diversities and to estimate coalescence ages of the binary haplotypes. The majority of binary haplotypes showed a nonuniform distribution across the continent. Analysis of molecular variance detected a high level of interpopulation diversity (PhiST=0.342), which appears to be partially related to the geography (PhiCT=0.230). In sub-Saharan Africa, the recent spread of a set of haplotypes partially erased pre-existing diversity, but a high level of population (PhiST=0.332) and geographic (PhiCT=0.179) structuring persists. Correspondence analysis shows that three main clusters of populations can be identified: northern, eastern, and sub-Saharan Africans. Among the latter, the Khoisan, the Pygmies, and the northern Cameroonians are clearly distinct from a tight cluster formed by the Niger-Congo-speaking populations from western, central western, and southern Africa. Phylogeographic analyses suggest that a large component of the present Khoisan gene pool is eastern African in origin and that Asia was the source of a back migration to sub-Saharan Africa. Haplogroup IX Y chromosomes appear to have been involved in such a migration, the traces of which can now be observed mostly in northern Cameroon.

Graphical abstract Highlights • The Y-STR profiles of 477 northern African males were obtained using the 27-loci Yfiler® Plus kit. • About 46% of the samples belonged to the recent E-M81 Y haplogroup. • The AMOVA analysis showed significant differences between populations and countries. • The number of identical Y-STR profiles was drastically reduced using the Yfiler® Plus compared to Yfiler. Abstract The male-specific northern African genetic pool is characterised by a high frequency of the E-M81 haplogroup, which expanded in very recent times (2–3 kiloyears ago). As a consequence of their recent coalescence, E-M81 chromosomes often cannot be completely distinguished on the basis of their Y-STR profiles, unless rapidly-mutating Y-STRs (RM Y-STRs) are analysed. In this study, we used the Yfiler® Plus kit, which includes 7 RM Y-STRs and 20 standard Y-STR, to analyse 477 unrelated males coming from 11 northern African populations sampled from Morocco, Algeria, Libya and Egypt. The Y chromosomes were assigned to monophyletic lineages after the analysis of 72 stable biallelic polymorphisms and, as expected, we found a high proportion of E-M81 subjects (about 46%), with frequencies decreasing from west to east. We found low intra-population diversity indexes, in particular in the populations that experienced long-term isolation. The AMOVA analysis showed significant differences between the countries and between most of the 11 populations, with a rough differentiation between northwestern Africa and northeastern Africa, where the Egyptians Berbers from Siwa represented an outlier population. The comparison between the Yfiler® and the Yfiler® Plus network of the E-M81 Y chromosomes confirmed the high power of discrimination of the latter kit, thanks to higher variability of the RM Y-STRs: indeed, the number of chromosomes sharing the same haplotype was drastically reduced from 201 to 81 and limited, in the latter case, to subjects from the same population. [ABSTRACT FROM AUTHOR]

Recently, thirteen rapidly mutating Y-STRs (RM Y-STRs), characterized by a mutation rate higher than 10−2/STR/generation, have been proven to be extremely useful in distinguishing among close male relatives. Six of these RM-YSTRs have been included in the Yfiler™ Plus PCR Amplification Kit, which shows the highest discriminatory power among Y-STR commercial multiplex currently available. In this study, we used Yfiler Plus to analyze 1437 males from eastern, northern and sub-Saharan Africa (462, 477 and 498 subjects, respectively). 242 out of 1437 subjects were found to share 102 Y-STR haplotypes, resulting in a low discrimination capacity (DC = 0.90) as compared to other continental regions. With few exceptions, Y-STR haplotype sharing was limited to subjects coming from the same country and ethnic group, and belonging to the same binary Y-SNP haplogroup, suggesting possible familial relationships along the male lineage. In order to evaluate the presence of hidden familial relationships, all the 242 subjects sharing a Y-STR haplotype were further genotyped for 16 autosomal STRs using the AmpFℓSTR® NGM SElect™ PCR Amplification Kit. Blind search and simulation test analyses for kinship using the Familias software revealed the presence of a low proportion of close relatives (second degree or closer) in our sample set. These findings show that close relatedness explains only a relatively small proportion of the observed Y-STR haplotype sharing, suggesting that a higher number of RM Y-STRs should be included in commercial kits to improve the discrimination power of male-specific markers in regions characterized by high levels of endogamy. [ABSTRACT FROM AUTHOR]

By using the recently introduced 6-dye Yfiler ® Plus multiplex, we analyzed 462 males belonging to 20 ethnic groups from four eastern African countries (Eritrea, Ethiopia, Djibouti and Kenya). Through a Y-STR sequence analysis, combined with 62 SNP-based haplogroup information, we were able to classify observed microvariant alleles at four Y-STR loci as either monophyletic (DYF387S1 and DYS458) or recurrent (DYS449 and DYS627). We found evidence of non-allelic gene conversion among paralogous STRs of the two-copy locus DYF387S1. Twenty-two diallelic and triallelic patterns observed at 13 different loci were found to be significantly over-represented (p < 10 −6 ) among profiles obtained from cell lines compared to those from blood and saliva. Most of the diallelic/triallelic patterns from cell lines involved recurrent mutations at rapidly mutating loci (RM Y-STRs) included in the multiplex (p < 10 −2 ). At haplotype level, intra-population diversity indices were found to be among the lowest so far reported for the Yfiler ® Plus, while statistically significant differences among countries and ethnic groups were detected when considering haplotype frequencies alone (F ST ) or by using molecular distances among haplotypes (Φ ST ). The strong population subdivision observed is probably the consequence of the patrilineal social organization of most eastern African ethnic groups, and suggests caution in the use of country-based haplotype frequency distributions for forensic inferences in this region. [ABSTRACT FROM AUTHOR]

Y chromosome short tandem repeats (Y-STRs) typing is becoming increasingly popular in forensic casework mainly because it allows the recovery of male-specific genetic information from severely unbalanced male-female DNA mixtures. The relatively low discrimination power of conventional Y-STR multiplexes, due to linkage disequilibrium among polymorphic loci, has been partially overcome by the introduction of rapidly mutating Y microsatellites (RM Y-STRs) with mutation rates exceeding 1 × 10-2/generation. In previous works, we reported an unexpectedly high level of haplotype sharing among African males using the Yfiler Plus PCR Amplification kit, the most powerful commercially available system, including 19 conventional Y-STRs and 6 RM Y-STRs. In particular, analyzing 1370 males from northern, eastern and central Africa, 240 subjects were found to share 100 Y-STR haplotypes. We attributed the relatively low discrimination capacity to several factors including patrilocality, endogamy, sampling bias and degree of urbanization. In the present study, using a blind search analysis based on 16 autosomal STRs, we first investigated the kinship between pairs of African males previously found to share the Yfiler Plus haplotype; then, we evaluated the improvement in identification capacity allowed by a PCR multiplex assay (RM-YPlex) based on 13 "first generation" RM Y-STR, seven of which are not included in the Yfiler Plus multiplex. Among 228 pairs of males sharing a Yfiler Plus haplotype, we detected 134 related (cousins or closer) and 94 unrelated (or distantly related) pairs of subjects. By using the RM-YPlex, we observed a full genotype concordance for the six loci shared with the Yfiler Plus, while the additional seven RM Y-STRs allowed the discrimination among 58.2 % related pairs and 84.0 % unrelated pairs. The discrimination capacity increased from 0.898 to 0.958, while the proportion of males sharing a haplotype decreased from 17.5 % to 8.0 %. These findings further highlight the capability of RM Y-STRs to distinguish males even in close kinship scenarios and in sub-structured populations as African ones, but at the same time call for the discovery and testing of additional RM Y-STRs to fully differentiate male relatives. • Discrimination power of RM Y-STRs in endogamous African populations was investigated. • Low discrimination power previously observed is only partially due to close kinship. • Discrimination capacity increased from 0.898 (Yfiler Plus) to 0.958 using RM Y-STRs. • Additional RM Y-STRs are required to fully differentiate male relatives. [ABSTRACT FROM AUTHOR]