Distribution of HLA‐DRB1 Alleles in Patients With Antiphospholipid Syndrome and Their Association With Antiphospholipid Antibodies Presence and Damage Indexes

Antiphospholipid syndrome (APS) is frequently coexisting with systemic lupus erythematosus (SLE) and the knowledge on its genetic background is essential. The objective of this work was to assess distribution of human leukocyte antigen (HLA)-DRB1 alleles in patients with APS with or without SLE in the context of Polish population data. The study was performed in a group of 112 patients with APS and healthy subjects to assess the distribution of HLA-DRB1 alleles in patients with APS and their association with clinical characteristics of patients with APS-antiphospholipid antibodies (aPLs) presence and disease activity/damage indexes. The distribution of HLA-DRB1 alleles showed significant differences between patients with APS and healthy subjects. Allelic variant HLA-DRB1<i>⁣</i> ^<i>∗</i> 1.15 was identified as risk alleles for APS observed in patients with APS (odds ratio (OR): 2.06 (1.27, 3.23), <i>p</i>=0, 004), while HLA-DRB1<i>⁣</i> ^<i>∗</i> 1.07 showed significant protective association (OR: 0.37 (0.14-0.76), <i>p</i>=0, 006). In subgroup of patients with coexisting SLE allelic variants above were not identified as risk or protective, while protective association was described for HLA-DRB1<i>⁣</i> ^<i>∗</i> 01, but not for patients in primary APS group. Presence of antibodies anti-<i>β</i> ₂-glycoprotein-I (a<i>β</i> ₂GPI) IgA and against domain 1, anti-phosphatidylserine/prothrombin (aPS/PT) and anticardiolipin antibody (aCL) IgA all the antibodies which were negatively associated with HLA-DRB1<i>⁣</i> ^<i>∗</i> 15.01 carriers, what was reported for the first time may be suitable in discussion about value of these antibodies in practice and scientific research. This study clearly shows that primary APS has a distinct HLA-DRB1 associations as compared with SLE with a strong positive association with HLA-DRB1<i>⁣</i> ^<i>∗</i> 15.01 allele and a protective association with HLA-DRB1<i>⁣</i> ^<i>∗</i> 07.01.