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

## TL;DR

This study examines HLA-DRB1 alleles in antiphospholipid syndrome patients, finding specific alleles linked to disease risk and antibody presence.

## Contribution

Identifies novel HLA-DRB1 allele associations with APS and specific antiphospholipid antibodies in a Polish population.

## Key findings

- HLA-DRB1*15.01 is a risk allele for primary APS, while HLA-DRB1*07.01 is protective.
- Certain antiphospholipid antibodies are negatively associated with HLA-DRB1*15.01 carriers.
- APS and SLE subgroups show distinct HLA-DRB1 allele associations.

## Abstract

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⁣∗1.15 was identified as risk alleles for APS observed in patients with APS (odds ratio (OR): 2.06 (1.27, 3.23), p=0, 004), while HLA-DRB1⁣∗1.07 showed significant protective association (OR: 0.37 (0.14–0.76), p=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⁣∗01, but not for patients in primary APS group. Presence of antibodies anti-β2-glycoprotein-I (aβ2GPI) 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⁣∗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⁣∗15.01 allele and a protective association with HLA-DRB1⁣∗07.01.