The genetic legacy of the Yaghnobis: A witness of an ancient Eurasian ancestry in the historically reshuffled central Asian gene pool

OBJECTIVES

The Yaghnobis are an ethno-linguistic minority historically settled along the Yaghnob River in the Upper-Zarafshan Valley in Tajikistan. They speak a language of Old Sogdian origin, which is the only present-day witness of the Lingua Franca used along the Silk Road in Late Antiquity. The aim of this study was to reconstruct the genetic history of this community in order to shed light on its isolation and genetic ancestry within the Euro-Asiatic context.

MATERIALS AND METHODS

A total of 100 DNA samples were collected in the Yaghnob and Matcha Valleys during several expeditions and their mitochondrial, Y-chromosome and autosomal genome-wide variation were compared with that from a large set of modern and ancient Euro-Asiatic samples.

RESULTS

Findings from uniparental markers highlighted the long-term isolation of the Yaghnobis. Mitochondrial DNA ancestry traced an ancient link with Middle Eastern populations, whereas Y-chromosome legacy showed more tight relationships with Central Asians. Admixture, outgroup-f3, and D-statistics computed on autosomal variation corroborated Y-chromosome evidence, pointing respectively to low Anatolian Neolithic and high Steppe ancestry proportions in Yaghnobis, and to their closer affinity with Tajiks than to Iranians.

DISCUSSION

Although the Yaghnobis do not show evident signs of recent admixture, they could be considered a modern proxy for the source of gene flow for many Central Asian and Middle Eastern groups. Accordingly, they seem to retain a peculiar genomic ancestry probably ascribable to an ancient gene pool originally wide spread across a vast area and subsequently reshuffled by distinct demographic events occurred in Middle East and Central Asia.

Identification of extra alleles in DYS385a/b multi-allelic patterns

Y chromosome short tandem repeats (Y-STRs) are widely used in forensic DNA analysis. Y-STRs usually genotyped as a monoallelic pattern, or a diallelic pattern at some double-copy loci. Abnormal genotypes with three or four alleles have been reported at DYS385a/b, which is a double-copy locus. However, multi-allelic patterns with more than four alleles have not been reported at this locus. In this study, abnormal five-allelic patterns at DYS385a/b locus were observed in 2 out of 7760 unrelated males from Henan Province, detected by the HG19+14Y fluorescence detection kit; and abnormal six-allelic pattern was observed in 1 out of 4920 unrelated males from Guangdong Province, detected by the AGCU Data Y30 fluorescence kit. The genotypes of these abnormal samples were confirmed again by the Yfiler® Plus and PowerPlex® Y23 kits. In order to understand the genomic structure of the extra alleles at this locus, forward and reverse primers were designed to sequence the three samples. The results showed that the five-banded and six-banded pattern genotype did exist at DYS385a/b locus. These data enriched the knowledge about multi-allelic patterns at DYS385a/b locus, which allowed the use of DYS385a/b profile in forensic analysis, even with multi-allelic patterns.

Genetic diversity of Chinese cattle revealed by Y-SNP and Y-STR markers

With its vast territory and complex natural environment, China boasts rich cattle genetic resources. To gain the further insight into the genetic diversity and paternal origins of Chinese cattle, we analyzed the polymorphism of Y-SNPs (UTY19 and ZFY10) and Y-STRs (INRA189 and BM861) in 34 Chinese cattle breeds/populations, including 606 males representative of 24 cattle breeds/populations collected in this study as well as previously published data for 302 bulls. Combined genotypic data identified 14 Y-chromosome haplotypes that represented three haplogroups. Y2-104-158 and Y2-102-158 were the most common taurine haplotypes detected mainly in northern and central China, whereas the indicine haplotype Y3-88-156 predominates in southern China. Haplotypes Y2-108-158, Y2-110-158, Y2-112-158 and Y3-92-156 were private to Chinese cattle. The population structure revealed by multidimensional scaling analysis differentiated Tibetan cattle from the other three groups of cattle. Analysis of molecular variance showed that the majority of the genetic variation was explained by the genetic differences among groups. Overall, our study indicates that Chinese cattle retain high paternal diversity (H = 0.607 ± 0.016) and probably much of the original lineages that derived from the domestication center in the Near East without strong admixture from commercial cattle carrying Y1 haplotypes.

Y-profile evidence: Close paternal relatives and mixtures

We recently introduced a new approach to the evaluation of weight of evidence (WoE) for Y-chromosome profiles. Rather than attempting to calculate match probabilities, which is particularly problematic for modern Y-profiles with high mutation rates, we proposed using simulation to describe the distribution of the number of males in the population with a matching Y-profile, both the unconditional distribution and conditional on a database frequency of the profile. Here we further validate the new approach by showing that our results are robust to assumptions about the allelic ladder and the founder haplotypes, and we extend the approach in two important directions. Firstly, forensic databases are not the only source of background data relevant to the evaluation of Y-profile evidence: in many cases the Y-profiles of one or more relatives of the accused are also available. To date it has been unclear how to use this additional information, but in our simulation-based approach its effect is readily incorporated. We describe this approach and illustrate how the WoE that a man was the source of an observed Y-profile changes when the Y-profiles of some of his male-line relatives are also available. Secondly, we extend our new approach to mixtures of Y-profiles from two or more males. Surprisingly, our simulation-based approach reveals that observing a 2-male mixture that includes an alleged contributor's profile is almost as strong evidence as observing a matching single-contributor evidence sample, and even 3-male and 4-male mixtures are only slightly weaker.

Phylogenetic analysis and forensic evaluation among Rakhine, Marma, Hajong, and Manipuri tribes from four culturally defined regions of Bangladesh using 17 Y-chromosomal STRs

We have analyzed haplotypes for 17 Y chromosomal STR loci in Bangladeshi mainstream Bengali population and four largest ethnic groups inhabiting the North-Eastern and Southern region of Bangladesh using AmpFlSTR® Yfiler® PCR amplification systems. A total of 667 haplotypes from Bangladeshi Bangali, 157 from Rakhine, 144 from Marma, 112 from Hajong, and 136 from Manipuri individuals were observed with corresponding discrimination capacity (DC) of 0.973 for Bengali, 0.723 for Rakhine, 0.743 for Marma, 0.794 for Hajong, and 0.720 for Manipuri groups, respectively. In order to investigate genetic relationship and the pattern of paternal contributions of the studied population, a comparison of the studied data with the published data from Y-STR haplotype reference database (YHRD) was conducted based on analysis of molecular variance (AMOVA). Construction of neighbour-joining tree revealed that the Rakhine population lies closer to a clade consisting, Korean and Japanese population. The Hajong population showed close affinity with Riang (Tripura, India) tribe followed by Marma population. On the other hand, Manipuri group is closely related to Thai population followed by Tamil and mainstream Bengali population.

Mediterranean Y-chromosome 2.0-why the Y in the Mediterranean is still relevant in the postgenomic era

CONTEXT

Due to its unique paternal inheritance, the Y-chromosome has been a highly popular marker among population geneticists for over two decades. Recently, the advent of cost-effective genome-wide methods has unlocked information-rich autosomal genomic data, paving the way to the postgenomic era. This seems to have announced the decreasing popularity of investigating Y-chromosome variation, which provides only the paternal perspective of human ancestries and is strongly influenced by genetic drift and social behaviour.

OBJECTIVE

For this special issue on population genetics of the Mediterranean, the aim was to demonstrate that the Y-chromosome still provides important insights in the postgenomic era and in a time when ancient genomes are becoming exponentially available.

METHODS

A systematic literature search on Y-chromosomal studies in the Mediterranean was performed.

RESULTS

Several applications of Y-chromosomal analysis with future opportunities are formulated and illustrated with studies on Mediterranean populations.

CONCLUSIONS

There will be no reduced interest in Y-chromosomal studies going from reconstruction of male-specific demographic events to ancient DNA applications, surname history and population-wide estimations of extra-pair paternity rates. Moreover, more initiatives are required to collect population genetic data of Y-chromosomal markers for forensic research, and to include Y-chromosomal data in GWAS investigations and studies on male infertility.

Carriers of mitochondrial DNA macrohaplogroup L3 basal lineages migrated back to Africa from Asia around 70,000 years ago

Background

The main unequivocal conclusion after three decades of phylogeographic mtDNA studies is the African origin of all extant modern humans. In addition, a southern coastal route has been argued for to explain the Eurasian colonization of these African pioneers. Based on the age of macrohaplogroup L3, from which all maternal Eurasian and the majority of African lineages originated, the out-of-Africa event has been dated around 60-70 kya. On the opposite side, we have proposed a northern route through Central Asia across the Levant for that expansion and, consistent with the fossil record, we have dated it around 125 kya. To help bridge differences between the molecular and fossil record ages, in this article we assess the possibility that mtDNA macrohaplogroup L3 matured in Eurasia and returned to Africa as basal L3 lineages around 70 kya.

Results

The coalescence ages of all Eurasian (M,N) and African (L3 ) lineages, both around 71 kya, are not significantly different. The oldest M and N Eurasian clades are found in southeastern Asia instead near of Africa as expected by the southern route hypothesis. The split of the Y-chromosome composite DE haplogroup is very similar to the age of mtDNA L3. An Eurasian origin and back migration to Africa has been proposed for the African Y-chromosome haplogroup E. Inside Africa, frequency distributions of maternal L3 and paternal E lineages are positively correlated. This correlation is not fully explained by geographic or ethnic affinities. This correlation rather seems to be the result of a joint and global replacement of the old autochthonous male and female African lineages by the new Eurasian incomers.

Conclusions

These results are congruent with a model proposing an out-of-Africa migration into Asia, following a northern route, of early anatomically modern humans carrying pre-L3 mtDNA lineages around 125 kya, subsequent diversification of pre-L3 into the basal lineages of L3, a return to Africa of Eurasian fully modern humans around 70 kya carrying the basal L3 lineages and the subsequent diversification of Eurasian-remaining L3 lineages into the M and N lineages in the outside-of-Africa context, and a second Eurasian global expansion by 60 kya, most probably, out of southeast Asia. Climatic conditions and the presence of Neanderthals and other hominins might have played significant roles in these human movements. Moreover, recent studies based on ancient DNA and whole-genome sequencing are also compatible with this hypothesis.

Electronic supplementary material

The online version of this article (10.1186/s12862-018-1211-4) contains supplementary material, which is available to authorized users.

North African-Mediterranean HLA genetic contribution in a population of the kidney transplant waiting list patients of Canary origin (Gran Canaria)

The peopling of the Canary Islands has been widely debated. The mitochondrial DNA and Y-chromosome data support the idea of a Berber genetic origin coming from the North of Africa (maternal) and a later contribution of the Spanish invaders (paternal). The frequencies of the HLA class II alleles from the Tenerife Island (another Canary Island) have previously been published, postulating a Berber and Atlantic/Iberian contributions to the current population. The HLA class I and class II allele frequencies, haplotype frequencies and phylogenetic comparisons were performed in 215 unrelated individuals from Gran Canaria Island (belonging to the kidney transplant waiting list), with at least three generations of ancestors from Canary Islands, in order to study the different ethnical HLA contributions to the genetic background of the Canary Islanders. Results showed the presence of a compound HLA haplotype of putative Phoenician-Berber origin, A*33:01-C*08:02-B*14:02-DRB1*03:01-DQB1*02:01, likely coming from the combination of haplotypes A*30:02-C*05:01-B*18:01-DRB1*03:01-DQB1*02:01 and A*33:01-C*08:02-B*14:02-DRB1*01:02-DQB1*05:01 of North African (probably Berber) and West Asian Mediterranean (probably Phoenician) origins, respectively. The latter haplotypes and others from the same origin (Berber/Phoenician) are also present in the population studied. Besides, other contributions from the North of Europe, North England-Iberian (Atlantic contribution), and Western Europe/Mediterraneans (Spanish colonization) are also discussed. These data conclude that the current genetic background of the Canary Islands inhabitants has been generated over the years by different ways with an original Phoenician-Berber substrate and several genetic contributions generated in different invasions.

Shared and Species-Specific Patterns of Nascent Y Chromosome Evolution in Two Guppy Species

Sex chromosomes form once recombination is halted around the sex-determining locus between a homologous pair of chromosomes, resulting in a male-limited Y chromosome. We recently characterized the nascent sex chromosome system in the Trinidadian guppy (Poeciliareticulata). The guppy Y is one of the youngest animal sex chromosomes yet identified, and therefore offers a unique window into the early evolutionary forces shaping sex chromosome formation, particularly the rate of accumulation of repetitive elements and Y-specific sequence. We used comparisons between male and female genomes in P. reticulata and its sister species, Endler’s guppy (P. wingei), which share an ancestral sex chromosome, to identify male-specific sequences and to characterize the degree of differentiation between the X and Y chromosomes. We identified male-specific sequence shared between P. reticulata and P. wingei consistent with a small ancestral non-recombining region. Our assembly of this Y-specific sequence shows substantial homology to the X chromosome, and appears to be significantly enriched for genes implicated in pigmentation. We also found two plausible candidates that may be involved in sex determination. Furthermore, we found that the P. wingei Y chromosome exhibits a greater signature of repetitive element accumulation than the P. reticulata Y chromosome. This suggests that Y chromosome divergence does not necessarily correlate with the time since recombination suppression. Overall, our results reveal the early stages of Y chromosome divergence in the guppy.

Non-invasive fetal sex diagnosis in plasma of early weeks pregnants using droplet digital PCR

Background

Fetal sex determination is useful for families at risk of X-linked disorders, such as Duchenne muscular dystrophy, adrenal hypoplasia, hemophilia. At first, this could be obtained through invasive procedures such as amniocentesis and chorionic villus sampling, having a 1% risk of miscarriage. Since the discovery of cell-free fetal DNA (cffDNA) in maternal plasma, noninvasive prenatal testing permits the early diagnosis of fetal sex through analysis of cffDNA. However, the low amount of cffDNA relative to circulating maternal DNA requires highly sensitive molecular techniques in order to perform noninvasive prenatal diagnosis. In this context we employed droplet digital PCR (ddPCR) in order to evaluate the earliest possible fetal sex determination from circulating DNA extracted from plasma of pregnant women at different gestational ages.

Methods

We identified the fetal sex on cffDNA extracted from 29 maternal plasma samples at early gestational ages, several of them not suitable for qPCR determination, using ddPCR designed for SRY gene target.

Results

All maternal plasma samples were determined correctly for SRY gene target using ddPCR even at very early gestational age (prior to 7 weeks).

Conclusions

The ddPCR is a robust, efficient and reliable technology for the earliest possible fetal sex determination from maternal plasma.

Y-chromosomal Status of Six Indo-European-speaking Arab Subpopulations in Chaharmahal and Bakhtiari Province, Iran

BACKGROUND

We analyzed the Y-chromosome haplogroups of six documented Arab subpopulations that accommodated separately in different counties of Chaharmahal and Bakhtiari Province but nowadays speak Indo-European language (Luri and Farsi).

METHODS

This was an outcome study conducted in 2015 to test whether there was any genetic relatedness among some Indo-European-speaking Arab subpopulation accommodated in a geographically similar region, Chaharmahal and Bakhtiari Province, Iran. Seven main Y-chromosome bi-allelic markers were genotyped in six documented Arab subpopulations. Therefore, after DNA extraction from blood samples, PCR reaction carried out by designed primers for J1-M267, J2-M172, and J-M304, I-M170, IJ-M429, F-M89 and K-M9 markers. Then PCR products after quality control on agarose gel were sequenced.

RESULTS

Most subjects (83.3%) belonged to F-M89 haplogroup. These subjects belonged to K-M9 (40%), J2-M172 (40%) and I-M170 (20%). Generally, there were at least three genetically distinct ancestors with a divergence date of about 22200 yr for I, 429000 for J and 47400 before present for K haplogroup and may show separate historical migrations of studied populations. As the most recent common ancestor (MRCA) of most of these populations, haplogroup F, lived about 40000-50000 yr ago, the data do not support a nearly close genetic relationship among all of these populations. However, there were populations with same haplogroups J2 (n=2), K (n=2), or with a closer MRCA, IJ haplogroups, among I and J2 haplogroups. Finding haplogroup I, a specific European haplogroup, among Arab populations was not expected.

CONCLUSION

Identification of various haplogroups in Arab subpopulations despite its small area and geographically conserved region of this part of Iranian plateau was unexpected.

Dispersals of the Siberian Y-chromosome haplogroup Q in Eurasia

The human Y-chromosome has proven to be a powerful tool for tracing the paternal history of human populations and genealogical ancestors. The human Y-chromosome haplogroup Q is the most frequent haplogroup in the Americas. Previous studies have traced the origin of haplogroup Q to the region around Central Asia and Southern Siberia. Although the diversity of haplogroup Q in the Americas has been studied in detail, investigations on the diffusion of haplogroup Q in Eurasia and Africa are still limited. In this study, we collected 39 samples from China and Russia, investigated 432 samples from previous studies of haplogroup Q, and analyzed the single nucleotide polymorphism (SNP) subclades Q1a1a1-M120, Q1a2a1-L54, Q1a1b-M25, Q1a2-M346, Q1a2a1a2-L804, Q1a2b2-F1161, Q1b1a-M378, and Q1b1a1-L245. Through NETWORK and BATWING analyses, we found that the subclades of haplogroup Q continued to disperse from Central Asia and Southern Siberia during the past 10,000 years. Apart from its migration through the Beringia to the Americas, haplogroup Q also moved from Asia to the south and to the west during the Neolithic period, and subsequently to the whole of Eurasia and part of Africa.

The geographic mosaic of Ecuadorian Y-chromosome ancestry

Ecuadorians originated from a complex mixture of Native American indigenous people with Europeans and Africans. We analyzed Y-chromosome STRs (Y-STRs) in a sample of 415 Ecuadorians (145 using the AmpFlSTR^® Yfiler™ system [Life Technologies, USA] and 270 using the PowerPlex^®Y23 system [Promega Corp., USA]; hereafter Yfiler and PPY23, respectively) representing three main ecological continental regions of the country, namely Amazon rainforest, Andes, and Pacific coast. Diversity values are high in the three regions, and the PPY23 exhibits higher discrimination power than the Yfiler set. While summary statistics, AMOVA, and R_ST distances show low to moderate levels of population stratification, inferred ancestry derived from Y-STRs reveal clear patterns of geographic variation. The major ancestry in Ecuadorian males is European (61%), followed by an important Native American component (34%); whereas the African ancestry (5%) is mainly concentrated in the Northwest corner of the country. We conclude that classical procedures for measuring population stratification do not have the desirable sensitivity. Statistical inference of ancestry from Y-STRS is a satisfactory alternative for revealing patterns of spatial variation that would pass unnoticed when using popular statistical summary indices.

Genetic diversity in Svaneti and its implications for the human settlement of the Highland Caucasus

OBJECTIVES

In this study, we characterized genetic diversity in the Svans from northwestern Georgia to better understand the phylogeography of their genetic lineages, determine whether genetic diversity in the highland South Caucasus has been shaped by language or geography, and assess whether Svan genetic diversity was structured by regional residence patterns.

MATERIALS AND METHODS

We analyzed mtDNA and Y-chromosome variation in 184 individuals from 13 village districts and townlets located throughout the region. For all individuals, we analyzed mtDNA diversity through control region sequencing, and, for males, we analyzed Y-chromosome diversity through SNP and STR genotyping. The resulting data were compared with those for populations from the Caucasus and Middle East.

RESULTS

We observed significant mtDNA heterogeneity in Svans, with haplogroups U1-U7, H, K, and W6 being common there. By contrast, ∼78% of Svan males belonged to haplogroup G2a, with the remainder falling into four other haplogroups (J2a1, I2, N, and R1a). While showing a distinct genetic profile, Svans also clustered with Caucasus populations speaking languages from different families, suggesting a deep common ancestry for all of them. The mtDNA data were not structured by geography or linguistic affiliation, whereas the NRY data were influenced only by geography.

DISCUSSION

These patterns of genetic variation confirm a complex set of geographic sources and settlement phases for the Caucasus highlands. Such patterns may also reflect social and cultural practices in the region. The high frequency and antiquity of Y-chromosome haplogroup G2a in this region further points to its emergence there.

Y-STR Haplogroup Diversity in the Jat Population Reveals Several Different Ancient Origins

The Jats represent a large ethnic community that has inhabited the northwest region of India and Pakistan for several thousand years. It is estimated the community has a population of over 123 million people. Many historians and academics have asserted that the Jats are descendants of Aryans, Scythians, or other ancient people that arrived and lived in northern India at one time. Essentially, the specific origin of these people has remained a matter of contention for a long time. This study demonstrated that the origins of Jats can be clarified by identifying their Y-chromosome haplogroups and tracing their genetic markers on the Y-DNA haplogroup tree. A sample of 302 Y-chromosome haplotypes of Jats in India and Pakistan was analyzed. The results showed that the sample population had several different lines of ancestry and emerged from at least nine different geographical regions of the world. It also became evident that the Jats did not have a unique set of genes, but shared an underlying genetic unity with several other ethnic communities in the Indian subcontinent. A startling new assessment of the genetic ancient origins of these people was revealed with DNA science.

MITOCHONDRIAL DNA VARIATION IN THE FIELD VOLE (MICROTUS AGRESTIS): REGIONAL POPULATION STRUCTURE AND COLONIZATION HISTORY

Restriction fragment length polymorphism analysis of mitochondrial DNA (mtDNA) was used to examine the genetic structure among field voles (Microtus agrestis) from southern and central Sweden. A total of 57 haplotypes was identified in 158 voles from 60 localities. Overall mtDNA diversity was high, but both haplotype and nucleotide diversity exhibited pronounced geographic heterogeneity. Phylogenetic analyses revealed a shallow tree with seven primary mtDNA lineages separated by sequence divergences ranging from 0.6% to 1.0%. The geographic structure of mtDNA diversity and lineage distribution was complex but strongly structured and deviated significantly from an equilibrium situation. The extensive mtDNA diversity observed and the recent biogeographic history of the region suggests that the shallow mtDNA structure in the field vole cannot be explained solely by stochastic lineage sorting in situ or isolation by distance. Instead, the data suggest that the genetic imprints of historical demographic conditions and vicariant geographic events have been preserved and to a large extent determine the contemporary geographic distribution of mtDNA variation. A plausible historical scenario involves differentiation of mtDNA lineages in local populations in glacial refugia, a moving postglacial population structure, and bottlenecks and expansions of mtDNA lineages during the postglacial recolonization of Sweden. By combining the mtDNA data with an analysis of Y-chromosome variation, a specific population unit was identified in southwestern Sweden. This population, defined by a unique mtDNA lineage and fixation of a Y-chromosome variant, probably originated in a population bottleneck in southern Sweden about 12,000 to 13,000 calendar years ago.

Differences in genetic structure assessed using Y-chromosome and mitochondrial DNA markers do not shape the contributions to diversity in African sires

Up to 173 African sires belonging to 11 different subpopulations representative of four cattle groups were analysed for six Y-specific microsatellite loci and a mitochondrial DNA fragment. Differences in Y-chromosome and mtDNA haplotype structuring were assessed. In addition, the effect of such structuring on contributions to total genetic diversity was assessed. Thirty-five Y-chromosome and 71 mtDNA haplotypes were identified. Most Y-chromosomes analysed (73.4%) were of zebu origin (11 haplotypes). Twenty-two Y-haplotypes (44 samples) belonged to the African taurine subfamily Y2a. All mtDNA haplotypes belonged to the "African" taurine T1 haplogroup with 16 samples and nine haplotypes belonging to a recently identified subhaplogroup (T1e). Median-joining networks showed that Y-chromosome phylogenies were highly reticulated with clear separation between zebu and taurine clusters. Mitochondrial haplotypes showed a clear star-like shape with small number of mutations separating haplotypes. Mitochondrial-based F_ST -statistics computed between cattle groups tended to be statistically non-significant (p > .05). Most F_ST values computed among groups and subpopulations using Y-chromosome markers were statistically significant. AMOVA confirmed that divergence between cattle groups was only significant for Y-chromosome markers (Φ_CT  = 0.209). At the mitochondrial level, African sires resembled an undifferentiated population with individuals explaining 94.3% of the total variance. Whatever the markers considered, the highest contributions to total Nei's gene diversity and allelic richness were found in West African cattle. Genetic structuring had no effect on patterns of contributions to diversity.

Phylogeography of human Y-chromosome haplogroup Q3-L275 from an academic/citizen science collaboration

Background

The Y-chromosome haplogroup Q has three major branches: Q1, Q2, and Q3. Q1 is found in both Asia and the Americas where it accounts for about 90% of indigenous Native American Y-chromosomes; Q2 is found in North and Central Asia; but little is known about the third branch, Q3, also named Q1b-L275. Here, we combined the efforts of population geneticists and genetic genealogists to use the potential of full Y-chromosome sequencing for reconstructing haplogroup Q3 phylogeography and suggest possible linkages to events in population history.

Results

We analyzed 47 fully sequenced Y-chromosomes and reconstructed the haplogroup Q3 phylogenetic tree in detail. Haplogroup Q3-L275, derived from the oldest known split within Eurasian/American haplogroup Q, most likely occurred in West or Central Asia in the Upper Paleolithic period. During the Mesolithic and Neolithic epochs, Q3 remained a minor component of the West Asian Y-chromosome pool and gave rise to five branches (Q3a to Q3e), which spread across West, Central and parts of South Asia. Around 3–4 millennia ago (Bronze Age), the Q3a branch underwent a rapid expansion, splitting into seven branches, some of which entered Europe. One of these branches, Q3a1, was acquired by a population ancestral to Ashkenazi Jews and grew within this population during the 1st millennium AD, reaching up to 5% in present day Ashkenazi.

Conclusions

This study dataset was generated by a massive Y-chromosome genotyping effort in the genetic genealogy community, and phylogeographic patterns were revealed by a collaboration of population geneticists and genetic genealogists. This positive experience of collaboration between academic and citizen science provides a model for further joint projects. Merging data and skills of academic and citizen science promises to combine, respectively, quality and quantity, generalization and specialization, and achieve a well-balanced and careful interpretation of the paternal-side history of human populations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-016-0870-2) contains supplementary material, which is available to authorized users.

Role of testosterone and Y chromosome genes for the masculinization of the human brain

Women with complete androgen insensitivity syndrome (CAIS) have a male (46,XY) karyotype but no functional androgen receptors. Their condition, therefore, offers a unique model for studying testosterone effects on cerebral sex dimorphism. We present MRI data from 16 women with CAIS and 32 male (46,XY) and 32 female (46,XX) controls.

METHODS

FreeSurfer software was employed to measure cortical thickness and subcortical structural volumes. Axonal connections, indexed by fractional anisotropy, (FA) were measured with diffusion tensor imaging, and functional connectivity with resting state fMRI.

RESULTS

Compared to men, CAIS women displayed a "female" pattern by having thicker parietal and occipital cortices, lower FA values in the right corticospinal, superior and inferior longitudinal tracts, and corpus callosum. Their functional connectivity from the amygdala to the medial prefrontal cortex, was stronger and amygdala-connections to the motor cortex weaker than in control men. CAIS and control women also showed stronger posterior cingulate and precuneus connections in the default mode network. Thickness of the motor cortex, the caudate volume, and the FA in the callosal body followed, however, a "male" pattern.

CONCLUSION

Altogether, these data suggest that testosterone modulates the microstructure of somatosensory and visual cortices and their axonal connections to the frontal cortex. Testosterone also influenced functional connections from the amygdala, whereas the motor cortex could, in agreement with our previous reports, be moderated by processes linked to X-chromosome gene dosage. These data raise the question about other genetic factors masculinizing the human brain than the SRY gene and testosterone. Hum Brain Mapp 38:1801-1814, 2017. © 2017 Wiley Periodicals, Inc.

Y-Chromosomal Microdeletion in Idiopathic Azoospermic and Severe Oligozoospermic Indonesian Men

AIM

to detect Y-chromosomal microdeletion in Indonesian men with azoospermia or severe oligozoospermia using multiplex PCR.

METHODS

we performed 2 multiplex PCR amplifications of the Azoospermia Factor (AZF) region in 71 men. Criteria for including a patient were fulfilled if they presented with azoospermia or severe oligozoospermia, with or without additional abnormalities of sperm motility or of head morphology, raised or normal levels of FSH, normal levels of LH and testosterone, and with no evidence of testicular tumors or other abnormalities. Five men participated as control persons.

RESULTS

partial deletion of AZFa was found in 11 men (15.49%), complete deletion of AZFb in 1 man (1.4%), and complete deletion of AZFc in 1 man (1.4%). The unspecific type of deletion was also detected, including the DBY gene in 2 men (2.81%), and partial deletion of both AZFa and AZFb in 2 men (2.81%). No AZF deletion was observed in the control probands. Related to the type of deletion, the AZFa and AZFb deletion showed spermatogenesis arrest in most tubules, while deletion of the DBY gene is associated with the sertoli cell only (SCO) syndrome.

CONCLUSION

the frequency of partial deletion of AZFa was found to be relatively high in our center. The type of deletion is associated with the testicular histology.

On the Bantu expansion

Here we report the results of fine resolution Y chromosomal analyses (Y-SNP and Y-STR) of 267 Bantu-speaking males from three populations located in the southeast region of Africa. In an effort to determine the relative Y chromosomal affinities of these three genotyped populations, the findings are interpreted in the context of 74 geographically and ethnically targeted African reference populations representing four major ethno-linguistic groups (Afro-Asiatic, Niger Kordofanin, Khoisan and Pygmoid). In this investigation, we detected a general similarity in the Y chromosome lineages among the geographically dispersed Bantu-speaking populations suggesting a shared heritage and the shallow time depth of the Bantu Expansion. Also, micro-variations in the Bantu Y chromosomal composition across the continent highlight location-specific gene flow patterns with non-Bantu-speaking populations (Khoisan, Pygmy, Afro-Asiatic). Our Y chromosomal results also indicate that the three Bantu-speaking Southeast populations genotyped exhibit unique gene flow patterns involving Eurasian populations but fail to reveal a prevailing genetic affinity to East or Central African Bantu-speaking groups. In addition, the Y-SNP data underscores a longitudinal partitioning in sub-Sahara Africa of two R1b1 subgroups, R1b1-P25* (west) and R1b1a2-M269 (east). No evidence was observed linking the B2a haplogroup detected in the genotyped Southeast African Bantu-speaking populations to gene flow from contemporary Khoisan groups.

Inferring paternal history of rural African-derived Brazilian populations from Y chromosomes

OBJECTIVES

Quilombo remnants are relics of communities founded by runaway or abandoned African slaves, but often with subsequent extensive and complex admixture patterns with European and Native Americans. We combine a genetic study of Y-chromosome markers with anthropological surveys in order to obtain a portrait of quilombo structure and history in the region that has the largest number of quilombo remnants in the state of São Paulo.

METHODS

Samples from 289 individuals from quilombo remnants were genotyped using a set of 17 microsatellites on the Y chromosome (AmpFlSTR-Yfiler). A subset of 82 samples was also genotyped using SNPs array (Axiom Human Origins-Affymetrix). We estimated haplotype and haplogroup frequencies, haplotype diversity and sharing, and pairwise genetic distances through F_ST and R_ST indexes.

RESULTS

We identified 95 Y chromosome haplotypes, classified into 15 haplogroups. About 63% are European, 32% are African, and 6% Native American. The most common were: R1b (European, 34.2%), E1b1a (African, 32.3%), J1 (European, 6.9%), and Q (Native American, 6.2%). Genetic differentiation among communities was low (F_ST  = 0.0171; R_ST  = 0.0161), and haplotype sharing was extensive. Genetic, genealogical and oral surveys allowed us to detect five main founder haplotypes, which explained a total of 27.7% of the Y chromosome lineages.

CONCLUSIONS

Our results showed a high European patrilineal genetic contribution among the founders of quilombos, high amounts of gene flow, and a recent common origin of these populations. Common haplotypes and genealogical data indicate the origin of quilombos from a few male individuals. Our study reinforces the importance of a dual approach, involving the analysis of both anthropological and genetic data.

Identification of specific DNA methylation sites on the Y-chromosome as biomarker in prostate cancer

As a diagnostic biomarker, prostate special antigen (PSA) tests always generate false positive results and lead to unnecessary and/or repeat biopsies. Therefore, there is an urgent need for developing more sensitive, specific diagnostic biomarkers. We epigenotyped methylated sites in cancer tissues and adjacent normal tissues from 66 patients. In comparison with normal adjacent tissues, we observed that there were 6 aberrant methylation sites in prostate cancer tissues on the Y-chromosome. We further performed pyrosequencing using urine of PCa patients and we identified one methylated site (cg05163709) as a potential biomarker. We evaluated the predictive capacity of the aberrant methylated sites using the area under receiver operating characteristic (ROC) curve (AUC). The ROC analysis showed a higher AUC for cg05163709 (0.915) than prostate-specific antigen (PSA, 0.769). These results indicated that aberrant DNA methylation of cg05163709 on the Y-chromosome could serve as a potential diagnostic biomarker with high sensitivity and specificity.

Y-STR markers from Ladakh in the Himalayas

A total of 223 samples from the general population of Ladakh in Northwestern India were amplified at 17 Y-STR loci using the AmpFlSTR® Yfiler™ system. The DNA profiles generated were employed to generate allelic frequencies, gene diversity, haplotype diversity and discrimination capacity values as well as number of different haplotypes, fraction of unique haplotypes and Rst pair wise genetic distances. Multidimensional Scaling (MDS) and Correspondence Analysis (CA) were performed with the Rst values and allelic frequencies, respectively. The 17-loci discrimination capacity of Ladakh was found to be 0.8093. Eleven out of the 16 loci have diversity values greater than 0.6, and 13 loci possess values greater than 0.5. Ladakh exhibits no significant genetic difference to seven of the 15 reference forensic databases after Bonferroni correction, three of which are located in South Central Asian and four are from the Himalayan region. Rst genetic distance values before and after Bonferroni corrections illustrate the capacity of the Yfiler system to discriminate among Himalayan populations. The intermediate position of the Ladakh population in the MDS and CA plots likely reflects genetic flow and admixture with neighboring populations. In addition, the longitudinal partition of populations in the MDS and CA plots likely reflect human dispersals such as the silk road migrations.