Mitochondrial DNA polymorphisms in Southern African populations.
The subject of this thesis is mitochondrial DNA (mtDNA) variation in southern African populations. The purpose of this study was twofold. Firstly, mtDNA variations were used to investigate the genetic affinities of Negroid, Khoisan, Caucasoid and "Coloured" populations in an attempt to refine theories on southern African population affinities and prehistory. MtDNA variations were detected using two different methods. The first method makes use of restriction fragment length polymorphisms (RFLPs) detected with the restriction enzymes Hpal, BamUI, Haell, Mspl, Avail and Hindi in 795 unrelated individuals from twenty ethnic groups within the Khoisan, Negroid, Caucasoid and "Coloured" populations from South Africa and Namibia. The combinations of the various restriction enzyme patterns (morphs) for the enzymes Hpal, Bam HI, Hae II, Mspl, Avail and Hindi (in this order), were used to derive the mtDNA type for each individual studied. This resulted in the discovery of 52 distinct mtDNA types: 30 of which had been previously reported, 28 out of 32 resulted from new combinations of enzyme morphs and 4/32 were due to the discovery of new enzyme morphs (MspI-17 in the Ashkenazi Jewish population and AvaII-31, AvaII-32 and AvaII-33 in the South African "Coloured" population). The second method involves sequencing approximately 750 base pairs of mtDNA contained within the two hypervariable segments within the non-coding control region of the mtDNA molecule in 144 individuals, most of whom where investigated for mtDNA RFLP variations. Pairwise comparisons of mtDNA sequences revealed 119 variant sites which gave rise to 129 unique mtDNA types.
A thesis submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy.