In addition to the association with the DRB1 allele, 23 out of 27 samples from patients with hepatitis were positive for HLA-DQA1*03:03 compared with 11 out of 64 samples from controls (allele frequency of 0.54 compared with 0.09, respectively, OR of 12.3 (5.1–30.7), P = 1.9 × 10−11). This evidence concerns the gene HLA-DRB1 and hepatitis A virus infection.