HLA typing using PCR. M, DNA 1kb marker; C, positive controls for allele of interest; A, PCR with primers of internal control GAPDH (PCR product size = 576bp); B, PCR with primers of allele of interest; Allele of interest in a, HLA-DRB1*11 (PCR product size = 176bp); Allele of interest in b, HLA-DRB1*12 (PCR product size = 248bp); Lanes 1 to 17, Samples of aero-allergic patients.