Studies of random Black and White populations in North Carolina: hla antigen profile

HLA-A, -B, -DR, -DQ antigens in black North Americans

HLA antigens of black North Americans are not as well-characterized as those of other ethnic groups. We present results from HLA typing of black Americans using the 10th International Histocompatibility Workshop (IHW) sera. 1502 black Americans are typed for HLA-A, -B antigens. 128 black Americans are typed for HLA-DR, -DQ antigens. New specificities and splits established by the 10th IHW are identified in our data. Antigen frequency, gene frequency and haplotype frequency are computed for each phenotype observed. Haplotype A30--Bw42--DRw18--DQw4 and haplotype Aw36--Bw53 in strong linkage disequilibrium is characteristic of this black population. DR and DQ association patterns are similar to those of white North Americans. A major difference is the association of DRw8 with DQw7 in blacks versus an association of DRw8 with DQw4 in whites.

HLA genotypes and variant alleles in Sudanese families of Arab-Negroid tribal origin

The indigenous population of the Blue Nile Province, Sudan, is an Arab-Negroid admixture, although some isolates of west African origin (Fallata) have begun to intermix with the indigenous population. Consanguineous marriages are common in these Muslim families. Members of 22 nuclear families were typed for HLA class I and II antigens using complement-dependent microcytotoxicity with Ninth International Workshop (9th WS) and local reagents. Considerable polymorphism was observed at each locus with a majority of the World Health Organization (WHO)-recognized alleles represented in the parental sample, albeit at low frequency. Seven parental haplotypes carried A locus alleles which were not identical to WHO-recognized specificities. All appeared to be Aw19-related specificities. Five B locus serologic variants were observed; all appeared distinct from WHO-recognized specificities. In one family we observed a new DR-DQ association; DR4 segregated with DQw2, rather than with DQw3. As has been observed for several other genetic systems in these tribes, considerable polymorphism was found for all class I and class II gene products in spite of a high level of consanguinity. Tribal admixture and/or a selective advantage in protecting the population against disease may account for this unexpectedly high level of heterozygosity.

Study of HLA antigens in a population of Mali (West Africa)

Eighty-two healthy individuals have been typed for HLA-A, B, C, antigens, and 49 of them also for HLA DR alleles. They were a sample representative of 11 of the 14 Malian ethnic groups living in the area of Bamako (Mali). Phenotypic frequencies have been compared to those of other Negroid and Caucasoid reference populations. As expected, in Negroids the increased frequency of HLA A23, A28, A30, and ATh was confirmed in the present series. Additionally, a significantly increased frequency of HLA B5 (B51 and Bw52) was noted--already observed in some but not all Negroid populations. Conversely, a decreased frequency--compared with that usually found in Negroid population--was observed for the alleles Bw42, Bw58, Cw6, and DRw6. Our results underline the originality of the Malian population among Western Africans.

Probabilistic assessment of the degree of antigen sharing in couples with impaired reproductive performance

Increased histocompatibility antigen sharing has been reported in couples experiencing recurrent infertility problems. Mathematical expressions describing the probability distribution of the number of antigens shared by randomly mating couples are derived for a single locus, two linked loci, and multiple independent systems. These theoretical frequencies are applied in concert with conventional statistical procedures to evaluate hypotheses concerning antigen distributions. Extensions for simultaneous consideration of other genetic systems are discussed.

Study of the HLA system in the Haitian population

The HLA-A and HLA-B phenotypes of 329 unrelated Haitian adults were determined and gene and haplotype frequencies were estimated. A summary of the data is presented together with a brief comparison with American Black, American White, and African Black populations. HLA gene and haplotype frequencies of Haitians are quite similar to those for American Blacks. The frequency of Aw34 appears to be smaller in Haitians than in American and African Blacks. No statistically significant differences were found in the frequencies of B-locus antigens.

Lack of association between Alzheimer's disease and histocompatibility antigens

The present report describes the distribution of histocompatibility antigens in 52 patients with Alzheimer's disease. No significant associations were observed between this illness and particular HLA types before or after statistical correction for multiple comparisons. These findings are discussed in terms of the difficulties inherent in the clinical diagnosis of Alzheimer's disease and with regard to the choice of suitable control populations.