Y-STR studies of genetic genealogy, population and forensic genetics of Indian and Zulu groups in the Durban, KwaZulu-Natal area of South Africa.

Abstract

The combination of molecular genetics and surname analysis of short tandem repeat (STR) data has the potential to shed light on population structure and history, falling within the field of forensic deoxyribonucleic acid (DNA) analysis. Since the Y-chromosome DNA along with surnames are paternally inherited, non-related males sharing a surname should be more closely related in comparison to the general population. Currently, no surname studies based on the Indian population in South Africa exist. This study aimed to explore the genetic genealogy, population and forensic genetics of Indian (different geographic origin, religion and language) and Zulu males with different common surnames from Durban, KwaZulu-Natal. This was achieved by: (1) Collecting samples from 224 non-paternal lineage related North Indians males and generating DNA profiles, using the Yfiler® Plus kit to amplify 27 Y-chromosome STR (Y-STR) loci; (2) Comparing the genetics of the North Indian group to that of other groups with South Indian and Zulu African surnames found in the forensic lab database. Hypotheses were formulated to analyse differences in relationships at ethnic, region, religion, language and surname-based levels (Figure 1). Population and forensic genetic analyses revealed that the Yfiler® Plus gave a higher number of unique haplotypes and discrimination capacity and a lower haplotype match probability, validating its use in this study. Genetic structure was found amongst examined sub-groupings. AMOVA was significant for all levels tested, with exception to between South Indian surnames. There are no known barriers to intermarriage among people bearing these South Indian surnames. Structure and PCoA analysis showed the presence of two significant sub-populations, which were ethnic based. Population structure and diversity were not surname based, but rather at an ethic level. This could be attributed to polyphyletic origin (many surname origin) of the analysed surnames. Surname transmission was polyphyletic for all surname groups, showing overlapping haplotypes and clades, implying multiple founders/ lineages for each specific surname investigated. The data generated in this study will contribute to the Indian DNA profiling database and could potentially serve as a baseline for further research. Further research could include sequencing autosomal STRs and hypervariable regions of mtDNA. enetic genealogy is a field of growing interest, involving genealogical testing to determine genetic relationships between individuals. The combination of molecular genetics and surname analysis of Y-STR data has the potential to shed light on population structure and history and is within the field of HID (human Identification) forensic DNA analysis. Since DNA along with surnames are passed down from our ancestors, people with the same surname should have a greater chance of sharing common ancestry when compared with the general population. There are currently no surname studies based on the Indian or Zulu populations of SA. The primary focus of this study was on genetic genealogy, i.e. co-inheritance of surnames and Y-STRs. In addition, population and forensic genetics of a sample group of mainly Indian and Zulu people from the greater Durban area of KwaZulu-Natal (KZN), SA, was investigated to search for genetic structure in comparisons of groups based on (1) Ethnicity (Indian vs Zulu), (2) Region of origin in India (North vs South), (3) Religion (Hindu vs Muslim), (4) Language (Hindi vs Muslim (Urdu) vs Tamil Indians) and, (5) Surname-based groups originating from North India (surnames Khan, Maharaj and Singh), South India (surnames Govender, Naidoo and Pillay), and Africa (surnames Buthelezi, Cele, Dlamini, Mkhize and Zulu). Further, an attempt was made to establish baseline aspects of the social history of the North Indian groups in Durban, which relate to genetic genealogy. The age profile and number of generations since the first family member arrived in the Durban area from India were investigated, along with information on whether a North Indian individual shares his surname, city, religion and language with his child and paternal and maternal forefathers. DNA samples were collected from 224 non-parentally related North Indian males with the surnames Khan, Maharaj and Singh and the Yfiler® Plus Polymerase chain reaction (PCR) amplification kit was used to amplify 27 Y-STR loci, from which DNA profiles were generated. In order to extend the basis for comparison to other Durban area ethnic groups, Y-STR profiles, from the lab database, of South Indians (n = 90, surnames Govender, Naidoo and Pillay) and Zulus (n = 100, surnames Buthelezi, Cele, Dlamini, Mkhize and Zulu) were included in the sample set. Null Alleles were observed at 77.8 % (21 out of 27) of the different loci analysed, with most contained in loci DYS391, DYS389II and DYS448.