HLA-DRB1 and systemic lupus erythematosus: We used the geno-PDT to assess genotypic risk for our class II and class III association signals: HLA-DRB1 and the SNP rs419788. In the case-control analysis for HLA-DRB1, ORs with 95% CI were calculated and Fisher's exact test employed to assess statistically significant differences between HLA-DRB1 genotypes in lupus probands and healthy controls.