HLA-DRB1 and acute lymphoblastic leukemia: Although the frequencies of the A*03, DRB1*03, and DRB1*04 alleles were observed to be higher (p=0.006, p=0.003, and p=0.002, respectively) in patients with ALL, the frequencies of A*23, B*13, B*40, and DRB1*13 (p=0.002, p=0.07, p=0.002, and p=0.003, respectively) were observed to be lower.