Characteristics of HLA class I and class II polymorphisms in Rwandan women.

OBJECTIVE

To define HLA class I and class II polymorphisms in Rwandans.

METHODS

PCR-based HLA genotyping techniques were used to resolve variants of HLA-A, B, and C to their 2- or 4-digit allelic specificities, and those of DRB1 and DQB1 to their 4- or 5-digit alleles.

RESULTS

Frequencies of 14 A, 8 C, and 14 B specificities and of 13 DRB1 and 8 DQB1 alleles were >/=0.02 in a group of 280 Rwandan women. These major HLA factors produced 6 haplotypes extending across the class I and class II regions: A01-Cw04-B* 4501-DRB11503-DQB10602 (A1-Cw4-B12- DR15 - DQ6), A * 01 - Cw * 04 - B * 4901 -DRB1 * 1302-DQB10604 (A1-Cw4-B21-DR13-DQ6), A30 - Cw04 - B15 - DRB11101 - DQB10301 (A19-Cw4-B15-DR11-DQ7), A68-Cw07-B* 4901-DRB11302-DQB10604(A28-Cw7-B21- DR13 - DQ6), A30 - Cw07 - B5703 - DRB1 1303-DQB10301(A19 - Cw7 - B17 - DR13 - DQ7), and A74-Cw07-B4901-DRB11302-DQB1 0604 (A19-Cw7-B21-DR13-DQ6), respectively. Collectively, these extended haplotypes accounted for about 19% of the total. Other apparent class I-class II haplotypes (e.g., Cw17-B42-DRB10302-DQB10402, Cw06- B58-DRB11102-DQB10301, and Cw03- B15-DRB103011-DQB10201) did not extend to the telomeric HLA-A locus, and other 3-locus class I haplotypes (e.g., A68-Cw04-B15, A74-Cw04-B15, and A23-Cw07-B*4901) completely or partially failed to link with any specific class II alleles.

DISCUSSION

Frequent recombinations appeared to occur between the three evolutionarily conserved HLA blocks carrying the class I and class II loci. The HLA class I profile seen in Rwandans was not directly comparable with those known in the literature, although the class II profile appeared to resemble those in several African populations. These data provide additional evidence for the extensive genetic diversity in Africans.