A Comparison of HLA Data of the North American Black with African Black and North American Caucasoid Populations

Abstract

For purposes of genetic comparison, the available HLA data on United States and African Black, together with United States Caucasoid populations, are summarized. Antigen frequencies and pairwise linkage disequilibria are presented for the HLA‐A, ‐B and ‐C loci in Black populations typed for the 1975 Histocompatibility Testing Workshop. The Black population samples comprise 356 North American Blacks and 411 African Blacks of whom 222 were Bantu. These are compared with a sample of 503 American Caucasoids. All significant linkage disequilibria between the A and B loci found in North American Blacks were also present in the North American Caucasoids. Between the B and C loci, Bw35 and Cw4 were in strong linkage disequilibrium in all groups. Significantly strong association between the A and C loci (Aw28 with Cw3) were observed only in the African Blacks. There were unique disequilibria both in the American Caucasoids and African Blacks. Although the frequencies of many antigens in U.S. Blacks lie between those in Africans and U.S. Caucasoids, there are exceptions such as Aw33, Bw35, Cw4.

B15 Heterogeneity in East African Blacks

“…The present study confirms the existence of Bw6-associated B15 antigens in E. African Blacks, and demonstrates the following: that they are common, with a population frequency of about 30%; that there may be two if not three Bw6associated variants other than the established B15.1; that in this population the apparently strong association of these variants with C-locus antigens may be helpful in their identification (q.v. the identification of Bw22.1 and Bw22.2 in European Caucasians), noting the established phenomenon that HLA-B and C-locus antigen association may vary for different populations; and that the commonest of these variants could be "SV", consistent with the observed association of T2 (Cw2) with what were then B-locus "blanks" in African Blacks (Oliver & Festenstein 1975a, Wolf et al 1975, Payne et al 1977, and with the findings in Bristol and Leiden that three out of four cells with SV but none of three cells with Bu also carried Cw2 on Table 3 Segregation of a BlS-related antigen with Cw3 (Shirati family X I ) the same haplotype (Schreuder et al 1980).…”

HLA antigens and Graves' disease in Black South Africans

“…Furthermore, hyperthyroidism is relatively uncommon in Black South Africans compared to the local Caucasian population (Kalk 1981). Only two (A2 and B8) of nine HLA antigens or phenotype combinations, common in Caucasians but rare in Blacks (Payne et al 1977), occurred with increased frequency in Black patients. Similarly, only one (A28) of nine antigens or combinations, common in Blacks but rare in Caucasians (Payne et al 1977), occurred with increased frequency in Caucasian patients.…”

“…Only two (A2 and B8) of nine HLA antigens or phenotype combinations, common in Caucasians but rare in Blacks (Payne et al 1977), occurred with increased frequency in Black patients. Similarly, only one (A28) of nine antigens or combinations, common in Blacks but rare in Caucasians (Payne et al 1977), occurred with increased frequency in Caucasian patients. Thus it is unlikely, but not impossible, that racial mixing influenced HLA frequencies in the patient groups.…”

“…Only frequencies which were notably or significunrly different in the patient groups as a whole have been included. Caucasian population may have influenced the development of Graves' disease in our Black thyrotoxics, the incidence of HLA antigens and phenotypic combinations common in Caucasians and uncommon in Blacks (Payne et al 1977) were compared (Table 4a). The frequencies of HLA-A2 and HLA-B8 were notably greater in Black thyrotoxics than in Black controls and were similar to those of Caucasian controls.…”

“…To explore the possibility that an admixture of Black HLA antigens might have contributed to the lack of a significant increase in HLA antigens in Caucasian thyrotoxic pa-tients, HLA antigen and phenotypic combination frequencies, common in Blacks and uncommon in Caucasians (Payne et al 1977), were compared in Caucasian patients and controls and in Black controls (Table 4b).…”