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1.
Am J Hum Genet ; 110(5): 880-894, 2023 05 04.
Article in English | MEDLINE | ID: mdl-37105174

ABSTRACT

Using contemporary people as proxies for ancient communities is a contentious but necessary practice in anthropology. In southern Africa, the distinction between the Cape KhoeSan and eastern KhoeSan remains unclear, as ethnicity labels have been changed through time and most communities were decimated if not extirpated. The eastern KhoeSan may have had genetic distinctions from neighboring communities who speak Bantu languages and KhoeSan further away; alternatively, the identity may not have been tied to any notion of biology, instead denoting communities with a nomadic "lifeway" distinct from African agro-pastoralism. The Baphuthi of the 1800s in the Maloti-Drakensberg, southern Africa had a substantial KhoeSan constituency and a lifeway of nomadism, cattle raiding, and horticulture. Baphuthi heritage could provide insights into the history of the eastern KhoeSan. We examine genetic affinities of 23 Baphuthi to discern whether the narrative of KhoeSan descent reflects distinct genetic ancestry. Genome-wide SNP data (Illumina GSA) were merged with 52 global populations, for 160,000 SNPs. Genetic analyses show no support for a unique eastern KhoeSan ancestry distinct from other KhoeSan or southern Bantu speakers. The Baphuthi have strong affinities with early-arriving southern Bantu-speaking (Nguni) communities, as the later-arriving non-Nguni show strong evidence of recent African admixture possibly related to late-Iron Age migrations. The references to communities as "San" and "Bushman" in historic literature has often been misconstrued as notions of ethnic/biological distinctions. The terms may have reflected ambiguous references to non-sedentary polities instead, as seems to be the case for the eastern "Bushman" heritage of the Baphuthi.


Subject(s)
Genetic Variation , Genetics, Population , Humans , Africa, Southern , Black People/genetics , Ethnicity/genetics
2.
Int J Legal Med ; 135(6): 2275-2284, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34599363

ABSTRACT

We compare DNA mixture analysis via DNAˑVIEW® Mixture Solution™ and the current combined probability of inclusion (CPI) method of the South African Police Service (SAPS). South Africa has a high incidence of property-related crimes and sexual offences and consequently a great deal of low-template (LT-DNA) forensic DNA mixture casework and a perpetual backlog. A range of casework and laboratory-prepared sexual assault mixtures with initial male DNA amounts varying from about 2 to 200 cells were analysed to evaluate the benefits of a continuous model program. Unfortunately CPI methods are nearly useless for LT-DNA cases because of dropout-common from a mixture contribution of fewer than 20 or 30 cells. We further argue that proposed CPI elaborations to circumvent dropout lack supporting research or even explanation. Mixture Solution models mixture data as continuous rather than binary, with a mathematically coherent ("probabilistic") model which incorporates dropout and other phenomena realistically. Much more information is thereby utilised resulting in applicability to more cases (7 or fewer contributor cells suffice), stronger evidence against a suspect who is a mixture contributor and stronger evidence to absolve a non-contributor. Mixture Solution incidentally provides information which, along with rfu data, allows estimating contributions in terms of number of cells, which is a useful perspective. The method of calculation is explained.


Subject(s)
DNA Fingerprinting , DNA , Humans , Laboratories , Likelihood Functions , Male , Models, Statistical
3.
Trop Anim Health Prod ; 50(2): 399-404, 2018 Feb.
Article in English | MEDLINE | ID: mdl-29043474

ABSTRACT

The Afrikaner is an indigenous South African breed of "Sanga" type beef cattle along with breeds such as the Drakensberger and Nguni. Six composite breeds have been developed from crosses with the Afrikaner. Additionally, Afrikaner has been the base from which exotic breeds were established in South Africa through backcrossing. The study examined genetic diversity of Afrikaner cattle by genotyping 1257 animals from 27 herds in different geographic areas of South Africa and Namibia using 11 microsatellite markers. Multiple-locus assignment, performed using the Bayesian clustering algorithm of STRUCTURE, revealed three underlying genotypic groups. These groups were not geographically localized. Across herds and markers, the proportion of unbiased heterozygosity ranged from 0.49 to 0.72 averaging 0.57; mean number of alleles per locus ranged from 3.18 to 7.09, averaging 4.81; and allelic richness ranged from 2.35 to 3.38, averaging 2.67. It is concluded that a low inbreeding level of 2.7% and a moderate to high degree of variation still persists within the Afrikaner cattle breed, despite the recent decline in numbers of animals.


Subject(s)
Cattle/genetics , Genetic Variation , Africa, Southern , Alleles , Animals , Bayes Theorem , Breeding , Genotype , Heterozygote , Inbreeding , Microsatellite Repeats , Namibia , South Africa
4.
Int J Legal Med ; 128(2): 275-6, 2014 Mar.
Article in English | MEDLINE | ID: mdl-23892950

ABSTRACT

Allele frequency distributions for 15 tetrameric short tandem repeat (STR) loci were determined using the AmpFlSTR® Identifiler Plus™ PCR amplification kit. There was little evidence of departures from Hardy-Weinberg equilibrium or association of alleles of different loci in the population samples. The probability of identity values for the different populations range from 1/3.3 × 10(17) (White) to 1/1.88 × 10(18) (Coloured). The combined probability of paternal exclusion for the different population groups ranges from 0.9995858 (Coloured) to 0.9997874 (Indian).


Subject(s)
Black People/genetics , Gene Frequency/genetics , Genetic Loci/genetics , Genetics, Population , Microsatellite Repeats/genetics , Female , Forensic Genetics , Genotype , Humans , Male , Paternity , Polymerase Chain Reaction/methods , South Africa
5.
Sci Justice ; 62(3): 358-364, 2022 05.
Article in English | MEDLINE | ID: mdl-35598928

ABSTRACT

South Africa has one of the highest rape statistics in the world, with an average of 117 rapes reported daily. Y-STR genotyping is becoming a popular tool in the analysis of DNA evidence collected after a crime of a sexual nature has been committed, but has yet to be implemented in South Africa's forensic laboratories. This study aimed to investigate the forensic value of the 27 Yfiler™ Plus loci in the South African population. A total of 271 samples from the African, Asian/Indian, Mixed Ancestry1, and Caucasian populations at the University of the Free State in Bloemfontein, South Africa were amplified and analysed using ThermoFisher Scientific's Yfiler™ Plus PCR Amplification kit. Of the 271 samples, 261 were identified to be unique, with an overall discrimination capacity of 98.15%. Discrimination capacities ranged from 91.67% for the Asian/Indian population to 100% for the Mixed Ancestry population. The haplotype diversity across the four populations is 0.9999, with an average gene diversity across all loci of 0.717. The forensic parameters estimated in this study provide evidence for the potential use of the commercial Yfiler™ Plus PCR amplification kit in a forensic application in South Africa.


Subject(s)
Chromosomes, Human, Y , Forensic Genetics , Microsatellite Repeats , Chromosomes, Human, Y/genetics , DNA Fingerprinting , Gene Frequency , Genetics, Population , Humans , Rape , South Africa
6.
Mol Imaging Biol ; 22(1): 33-46, 2020 02.
Article in English | MEDLINE | ID: mdl-31016638

ABSTRACT

Positron emission tomography/x-ray computed tomography (PET/CT) has long been discussed as a promising modality for response evaluation in cancer. When designing respective clinical trials, several design issues have to be addressed, especially the number/timing of PET/CT scans, the approach for quantifying metabolic activity, and the final translation of measurements into a rule. It is unclear how well these issues have been tackled in quest of an optimised use of PET/CT in response evaluation. Medline via Ovid and Science Citation Index via Web of Science were systematically searched for articles from 2015 on cancer patients scanned with PET/CT before and during/after treatment. Reports were categorised as being either developmental or evaluative, i.e. focusing on either the establishment or the evaluation of a rule discriminating responders from non-responders. Of 124 included papers, 112 (90 %) were accuracy and/or prognostic studies; the remainder were response-curve studies. No randomised controlled trials were found. Most studies were prospective (62 %) and from single centres (85 %); median number of patients was 38.5 (range 5-354). Most (69 %) of the studies employed only one post-baseline scan. Quantification was mainly based on SUVmax (91 %), while change over time was most frequently used to combine measurements into a rule (79 %). Half of the reports were categorised as developmental, the other half evaluative. Most development studies assessed only one element (35/62, 56 %), most frequently the choice of cut-off points (25/62, 40 %). In summary, the majority of studies did not address the essential open issues in establishing PET/CT for response evaluation. Reasonably sized multicentre studies are needed to systematically compare the many different options when using PET/CT for response evaluation.


Subject(s)
Biomarkers, Tumor/analysis , Fluorodeoxyglucose F18/metabolism , Neoplasms/pathology , Positron Emission Tomography Computed Tomography/methods , Response Evaluation Criteria in Solid Tumors , Combined Modality Therapy , Humans , Neoplasms/diagnostic imaging , Neoplasms/metabolism , Neoplasms/therapy , Prognosis , Radiopharmaceuticals/metabolism , Treatment Outcome
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