HLA-DRB1 and rheumatoid arthritis: Similarly, RA association of HLA-DRB1 alleles displayed good correlation between both methods (Spearman’s rank correlation coefficient r = 0.974) with the riskiest allele HLA-DRB*04:01 (ZDISH = 37.04, r2ped = 0.79, PDISH = 2.44 × 10−300; ZSNP2HLA = 40.99, PSNP2HLA = 3.03 × 10−367) and the most protective allele HLA-DRB*13:01 (ZDISH = −17.03, r2ped = 0.66, PDISH = 5.24 × 10−65; ZSNP2HLA = −17.38, PSNP2HLA = 1.21 × 10−67; Fig. 2B).