title: C4 polymorphism and extended HLA haplotypes in Namibian San and Khoi and in South African Xhosa.
abstract: We studied C4A and C4B polymorphisms and HLA-B and -DR associations in the San, Khoi and Xhosa. C4A and C4B alleles were determined using conventional protein allotyping methods. The C4A*3, C4B*1 haplotype had a high frequency (30-55%) in all populations. The frequency of C4A*3, C4B*Q0 was 7-19%. The C4A*Q0, C4B*1 haplotype was frequent (15%) in the Khoi but very rare in the San (P < 0.001). C4A*12 A*91, C4B*Q0 was frequent in the Xhosa (15%) but rare in the San and Khoi (P < 0.001). Alleles C4A*5 and C4A*6, and the C4B*2 B*92 duplication were only found in the Xhosa. C4A alleles A*4, A*45, A*58, A*12, A*14, A*19 and the C4A*3 A*91 duplication were only found in the San/Khoi population group. In the San, fourteen extended haplotypes were found in a relatively high frequency (2-7%). In the Xhosa, one extended haplotype (B42, C4A*12 A*91, C4B*Q0, DR18) was found in a very high frequency (13%) and was characteristic for this group; five other extended haplotypes were found with a low frequency (< 3%).
authors.affiliation: Provincial Laboratory for Tissue Immunology, Cape Town, South Africa.
authors.forename: P C
authors.initials: PC
authors.lastname: Creemers
authors.forename: E D
authors.initials: ED
authors.lastname: du Toit
mesh_terms: D015934:Complement C4a / Q000235:genetics*; D015935:Complement C4b / Q000235:genetics*; D005787:Gene Frequency; D015235:HLA-B Antigens / Q000235:genetics*; D006684:HLA-DR Antigens / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D009276:Namibia; D011110:Polymorphism, Genetic; D013019:South Africa
chemical_list: D015235:HLA-B Antigens; D006684:HLA-DR Antigens; D015934:Complement C4a; D015935:Complement C4b