Lemba origins revisited: Tracing the ancestry of Y chromosomes in South African and Zimbabwean Lemba

Background. Previous historical, anthropological and genetic data provided overwhelming support for the Semitic origins of the Lemba, a Bantu-speaking people in southern Africa.Objective. To revisit the question concerning genetic affinities between the Lemba and Jews.Methods. Y-chromosome variation was examined in two Lemba groups: one from South Africa (SA) and, for the first time, a group from Zimbabwe (Remba), to re-evaluate the previously reported Jewish link.Results. A sample of 261 males (76 Lemba, 54 Remba, 43 Venda and 88 SA Jews) was initially analysed for 16 bi-allelic and 6 short tandem repeats (STRs) that resulted in the resolution of 102 STR haplotypes distributed across 13 haplogroups. The non-African component in the Lemba and Remba was estimated to be 73.7% and 79.6%, respectively. In addition, a subset of 91 individuals (35 Lemba, 24 Remba, 32 SA Jews) with haplogroup J were resolved further using 6 additional bi-allelic markers and 12 STRs to screen for the extended Cohen modal haplotype (CMH). Although 24 individuals (10 Lemba and 14 SA Jews) were identified as having the original CMH (six STRs), only one SA Jew harboured the extended CMH.Conclusions. While it was not possible to trace unequivocally the origins of the non-African Y chromosomes in the Lemba and Remba, this study does not support the earlier claims of their Jewish genetic heritage.

Drafting a Code of Conduct for Research under the Protection of Personal Information Act No. 4 of 2013

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A Genomic Portrait of Haplotype Diversity and Signatures of Selection in Indigenous Southern African Populations

We report a study of genome-wide, dense SNP (∼900K) and copy number polymorphism data of indigenous southern Africans. We demonstrate the genetic contribution to southern and eastern African populations, which involved admixture between indigenous San, Niger-Congo-speaking and populations of Eurasian ancestry. This finding illustrates the need to account for stratification in genome-wide association studies, and that admixture mapping would likely be a successful approach in these populations. We developed a strategy to detect the signature of selection prior to and following putative admixture events. Several genomic regions show an unusual excess of Niger-Kordofanian, and unusual deficiency of both San and Eurasian ancestry, which were considered the footprints of selection after population admixture. Several SNPs with strong allele frequency differences were observed predominantly between the admixed indigenous southern African populations, and their ancestral Eurasian populations. Interestingly, many candidate genes, which were identified within the genomic regions showing signals for selection, were associated with southern African-specific high-risk, mostly communicable diseases, such as malaria, influenza, tuberculosis, and human immunodeficiency virus/AIDs. This observation suggests a potentially important role that these genes might have played in adapting to the environment. Additionally, our analyses of haplotype structure, linkage disequilibrium, recombination, copy number variation and genome-wide admixture highlight, and support the unique position of San relative to both African and non-African populations. This study contributes to a better understanding of population ancestry and selection in south-eastern African populations; and the data and results obtained will support research into the genetic contributions to infectious as well as non-communicable diseases in the region

Development of a single base extension method to resolve Y chromosome haplogroups in sub-Saharan African populations

<p>Abstract</p> <p>Background</p> <p>The ability of the Y chromosome to retain a record of its evolution has seen it become an essential tool of molecular anthropology. In the last few years, however, it has also found use in forensic genetics, providing information on the geographic origin of individuals. This has been aided by the development of efficient screening methods and an increased knowledge of geographic distribution. In this study, we describe the development of single base extension assays used to resolve 61 Y chromosome haplogroups, mainly within haplogroups A, B and E, found in Africa.</p> <p>Results</p> <p>Seven multiplex assays, which incorporated 60 Y chromosome markers, were developed. These resolved Y chromosomes to 61 terminal branches of the major African haplogroups A, B and E, while also including a few Eurasian haplogroups found occasionally in African males. Following its validation, the assays were used to screen 683 individuals from Southern Africa, including south eastern Bantu speakers (BAN), Khoe-San (KS) and South African Whites (SAW). Of the 61 haplogroups that the assays collectively resolved, 26 were found in the 683 samples. While haplogroup sharing was common between the BAN and KS, the frequencies of these haplogroups varied appreciably. Both groups showed low levels of assimilation of Eurasian haplogroups and only two individuals in the SAW clearly had Y chromosomes of African ancestry.</p> <p>Conclusions</p> <p>The use of these single base extension assays in screening increased haplogroup resolution and sampling throughput, while saving time and DNA. Their use, together with the screening of short tandem repeat markers would considerably improve resolution, thus refining the geographic ancestry of individuals.</p

Ethical issues in genomic research on the African continent: experiences and challenges to ethics review committees

Abstract This is a report on a workshop titled ‘Ethics for genomic research across five African countries: Guidelines, experiences and challenges’, University of the Witwatersrand, Johannesburg, South Africa, 10 and 11 December 2012. The workshop was hosted by the Wits-INDEPTH partnership, AWI-Gen, as part of the H3Africa Consortium

Hierarchical Patterns of Global Human Y-Chromosome Diversity

We examined 43 biallelic polymorphisms on the nonrecombining portion of the Y chromosome (NRY) in 50 human populations encompassing a total of 2,858 males to study the geographic structure of Y-chromosome variation. Patterns of NRY diversity varied according to geographic region and method/level of comparison. For example, populations from Central Asia had the highest levels of heterozygosity, while African populations exhibited a higher level of mean pairwise differences among haplotypes. At the global level, 36% of the total variance of NRY haplotypes was attributable to differences among populations (i.e., Phi(ST) = 0.36). When a series of AMOVA analyses was performed on different groupings of the 50 populations, high levels of among-groups variance (Phi(CT)) were found between Africans, Native Americans, and a single group containing all 36 remaining populations. The same three population groupings formed distinct clusters in multidimensional scaling plots. A nested cladistic analysis (NCA) demonstrated that both population structure processes (recurrent gene flow restricted by isolation by distance and long-distance dispersals) and population history events (contiguous range expansions and long-distance colonizations) were instrumental in explaining this tripartite division of global NRY diversity. As in our previous analyses of smaller NRY data sets, the NCA detected a global contiguous range expansion out of Africa at the level of the total cladogram. Our new results support a general scenario in which, after an early out-of-Africa range expansion, global-scale patterns of NRY variation were mainly influenced by migrations out of Asia. Two other notable findings of the NCA were (1) Europe as a "receiver" of intercontinental signals primarily from Asia, and (2) the large number of intracontinental signals within Africa. Our AMOVA analyses also supported the hypothesis that patrilocality effects are evident at local and regional scales, rather than at intercontinental and global levels. Finally, our results underscore the importance of subdivision of the human paternal gene pool and imply that caution should be exercised when using models and experimental strategies based on the assumption of panmixia

Y-Chromosome variation in Southern African Khoe-San populations based on whole-genome sequences

Abstract: Although the human Y chromosome has effectively shown utility in uncovering facets of human evolution and population histories, the ascertainment bias present in early Y-chromosome variant data sets limited the accuracy of diversity and TMRCA estimates obtained from them. The advent of next-generation sequencing, however, has removed this bias and allowed for the discovery of thousands of new variants for use in improving the Y-chromosome phylogeny and computing estimates that are more accurate. Here, we describe the high-coverage sequencing of the whole Y chromosome in a data set of 19 male Khoe-San individuals in comparisonwith existingwholeY-chromosome sequence data.Due to the increased resolution,we potentially resolve the source of haplogroup B-P70 in the Khoe-San, and reconcile recently published haplogroup A-M51 data with the most recent version of the ISOGG Y-chromosome phylogeny. Our results also improve the positioning of tentatively placed new branches of the ISOGG Ychromosome phylogeny. The distribution ofmajor Y-chromosome haplogroups in the Khoe-San and other African groups coincide with the emerging picture of African demographic history;with E-M2 linked to the agriculturalist Bantu expansion, E-M35 linked to pastoralist eastern Africanmigrations, B-M112 linked to earlier east-south gene flow, A-M14 linked to shared ancestrywith central African rainforest hunter-gatherers, and A-M51 potentially unique to the Khoe-San