Polymorphism in the 5' terminal region of the mRNA of HLA-DQA1 gene: identification of four groups of transcripts and their association with polymorphism in the alpha 1 domain.

Relative to other loci in the MHC, the HLA-DQ locus exhibits an exceptional degree of polymorphism of both A1 and B1 genes, particularly in the region coding for ? and ? chains. Diversification of the association between different ? and ? molecules either in cis or in trans contributes to the structural diversity of the repertoire of cell-surface class II protein's in the population. In addition, structural allelic polymorphisms in the 5? regulatory region of both DQB1 and DQA1 shows several linkage groups with respect to the allelic coding sequence of the respective genes. We describe here the allelic polymorphism in the DQA1 mRNA structure located at the 5? untranslated terminal region. This portion of the mRNA molecule represents, in many genes, a cisacting regulatory sequence playing a role in the posttranscriptional mechanisms by which gene expression can be modulated. Based on detailed transcriptional analysis, we have been able to define at least four groups of transcripts in DQA1. The mRNA variability was associated with the polymorphism of the second exon of the DQA1 gene, coding for the a 1 domain and not with the DNA polymorphism in the 5? regulatory region.