GENETIC-STUDIES ON THE SEPTAGE POPULATION .2. POLYMORPHISMS OF THE PLASMA-PROTEINS F13A, F13B, ORM1, AHSG, C6, C7, AND APOC2

Using isoelectric focusing and immunoblotting techniques, we tested 27 0 plasma samples from 3 populations of Senegal (Wolof, Peul, Tukulor) to determine genetic variation at 7 protein loci (F13A, F13B, ORM1, AH SG, C6, C7, APOC2). Four of the seven systems (F13A, ORM1, AHSG, C6) h ave not been studied previously in sub-Saharan Africa, and one system (C7) has never been examined in any population of African ancestry. Th e assumption that F13B6, F13B*23, and APOC2*2 represent African marke r alleles is supported by this study. At the AHSG locus we observed a four-allele polymorphism rather than the two-allele polymorphism commo nly seen in other ethnic groups. At the C6 locus, in addition to the t wo common alleles C6A and C6*B, we observed three other alleles, one of which (C6A3), found at polymorphic frequencies, seems to be anothe r example of a unique African allele. The C7 locus was found to be mon omorphic in the Peul but polymorphic in the Wolof and the Tukulor. At the F13A and ORM1 loci, Senegalese have allele frequencies similar to those reported for American blacks. All three Senegalese samples displ ay typical African features, such as a high frequency of the F13B2 al lele and the presence of the APOC22 allele at a polymorphic level. Ho wever, some differences in allele frequencies have been found between the three groups, and this could have implications for reconstructing their remote history. A comparison of the present results with publish ed data from other populations indicates that these genetic systems no t only could be valuable in defining intraregional genetic relationshi ps but also could provide a highly meaningful picture of the relative distances that separate major human groups.