Analysis of HLA DP, DQ, and DR allesles in adult Italian rheumatoid arthritis patients

We analyzed the distribution of DRB1, DQA1, DQB1, and DPB1 allelic variants in 48 rheumatoid arthritis (RA) patients, compared with 109 Italian random controls, using PCR amplification and hybridization with specific oligonucleotides. We confirm the previously reported increase of DR4 specificity, in comparison with healthy Italian individuals. In particular, we find a statistically significant positive association of DRB1^*0401 and DRB1^*0404 alleles with RA. However, when we compare the DR4⁺ groups, none of the DRB1^*04 alleles is increased in the RA group. By sequence analysis, performed on 10 patients, we demonstrate that the DRB1^*04 genes of RA show no difference from the DRB1^*04 sequences previously published. From the molecular analysis of the other DRB1 polymorphic variants, we find a trend of positive association of DRB1^*0101 in DR4-negative patients versus DR4-negative healthy controls and, in the group of DR4-negative and/or DR1-negative patients, a similar increase of DRB1^*06. Also, we observe in RA patients a statistically significant increase of DQA1^*0301 and DQB1^*0302 accompanied by a significant decrease of DQA1^*0201, DQA1^*0501 and DQB1^*0201. Finally, from the analysis of DPB1 gene, it can be assessed that the distribution of DPB1 alleles does not differ significantly between RA patients and healthy controls.