Analysis of MHC class II DNA polymorphisms in Negroid subjects

Study of the MHC class II region is complicated by strong linkage disequilibrium between DR and DQ. Comparison of DR-DQ haplotypes between different races partly resolves this problem. We present the results of an analysis of DRB, DQA and DQB restriction fragment length polymorphisms in serologically DR-typed subjects of Negroid origin. Clearly distinguishable DRB RFLPs were observed for DR1,2,5,7 and w8. DR4,9 and w10 were uncommon in this group. DR3 was associated with two extended haplotypes, one characterised by the DQw4 allele, the other by the DQw2 allele. A recently recognised DQB RFLP (DQB 2c) was associated with DR7 and also occurred on DR5 and DR9 haplotypes. Both DR5 and DRw6 were heterogeneous in their DR-DQ relationships. Negroid subjects exhibit DR-DQ relationships distinct from other races. These provide scope for further study of MHC class II associations with disease.