| Abstract: | We have investigated polymorphism in the 5′-URR of the DQA1 gene by PCR-SSO method in a group of 55 Italian healthy individuals olygotyped for DRB1, DQA1, DQB1 genes and in 20 10th IHWS cell lines as controls. We used primers and oligos (X and Y box) supplied by 12th IHWS and a DIG-11-ddUTP/AMPPD method. We have detected eight QAP variants (1.1,1.2,1.3,1.4,2.1,3.1,4.1,4.2) in our samples. As far as the association of DR/DQ haplotype and QAP sequences, we observed cases of one to one relationship (DQA1*0201 and QAP2.1, DQA1*0301 and QAP3.1, DQA1*0401 and QAP4.2, DQA1*0501 and QAP4.1); cases in which the same QAP allele was present in different DQA1-DRB1 haplotypes (QAP1.2 with DQA1*0102 in DRB1*15-DQB1*0602 and DRB1*16-DQB1*0502 haplotypes or with DQA1*0103 in the DRB1*15-DQB1*0601 haplotypes; QAP1.3 linked to DQA1*0102, DQA1*0103 or DQA1*0104 in different haplotypes; QAP4.1 linked to DQA1*0501 in DRB1*11-DQB1*0301, DRB1*0301-DQB1*0201, DRB1*1303-DQB1*0301 haplotypes or to DQA1*0601 in DRB1*0803-DQB1*0301); cases where the same DQA1 allele is associated with different QAP sequences according to the DRB1 specificity (DQA1*0102 allele with QAP1.2 or QAP1.4 in DRB1*1302). Besides, we have observed that the QAP1.3, previously reported associated with DQA1*0101-DRB1*1401 haplotype, is really linked to DQA1*0104-DRB1*1401 haplotype. An intriguing data is that sometimes the same QAP is linked to different DQA1 alleles but to the same generic DRB1 allele: DRB1*02 haplotype includes always the QAP1.2 variant but can bring different DQA1 alleles (*0102 or *0103) and DRB1*08 haplotype has always the QAP4.2 variant with different DQA1 alleles (*0401 or *0601). The variability of linkage QAP-DQA1 can give further informations about HLA susceptibility in autoimmune diseases and in regulation of immune response in transplantation and oncology. |
