Study of 30 DNA markers in three southern African populations

Thirty anonymous DNA markers were investigated in Southern African Caucasoid, Negroid and San populations. Sixteen of these are new markers that were developed in our laboratory; the remainder are closely linked to the cystic fibrosis locus on chromosome 7. Average heterozygosity in the Caucasoid and Negroid populations was calculated at the loci identified by each of the anonymous probes, using two approaches, and was found to be .0020 and .0030 for the Caucasoid population and .0023 and .0025 for the Negroid population. Variation between populations (measured by FST) and between markers was calculated from allele frequency data gathered for all markers in the three populations. Significant differences in allele frequency between the populations were observed for the cystic fibrosis markers MET D, MET H and 7C22, with little or no variation observed in the Negroid and San populations. Mean heterozygosity (D) was found to be considerably lower in San (.250) than in Caucasoid (.373) and Negroid populations (.0320) and possible explanations for this are provided. The smallest genetic distance (60 x 10(-3)) was found between the Negroid and San populations, and the greatest distance between the Caucasoid and San populations (167 x 10(-3)).