HLA-DRB1 and dengue disease: When HLA-A*33:01 was analyzed for linkage disequilibrium with alleles in other loci found in this study to have a similar tendency in dengue patients (i.e., protection against severe dengue), we found that HLA-B*58:01 and HLA-DRB1*03:01 are in linkage disequilibrium with A*33:01 (data not shown).