Genetic association of antinuclear antibodies with HLA in JIA patients: a Swedish cohort study.

Background: Juvenile Idiopathic Arthritis (JIA) is a complex autoimmune disease and the most common chronic rheumatological disease affecting children under the age of 16. The etiology of JIA remains poorly understood, but evidence suggests a significant genetic predisposition.

Methods: We analyzed a Swedish cohort of 329 JIA patients and 728 healthy adult controls using the Illumina OmniExpress array for genotyping. HLA alleles were imputed from GWAS data using the SNP2HLA algorithm.

Results: Case-control analysis yielded 12 SNPs with genome-wide significant association to JIA, all located on chromosome 6 within the MHC class II gene region. Notably, the top SNP (rs28421666) was located adjacent to HLA-DQA1 and HLA-DRB1. HLA-DRB1*08:01, HLA-DQA1*04:01, and HLA-DQB1*04:02 were the haplotypes most strongly associated with an increased risk of JIA in the overall cohort. When analyzing disease specific subtypes, these alleles were associated with oligoarthritis and RF-negative polyarthritis. Within the complex linkage disequilibrium of the HLA-DRB1-DQA1-DQB1 haplotype, our analysis suggests that HLA-DRB1*08 might be the primary allele linked to JIA susceptibility. The HLA-DRB1*11 allele group was also independently associated with JIA and specifically enriched in the oligoarthritis patient group. Additionally, our study revealed a significant correlation between antinuclear antibody (ANA) positivity and specific HLA alleles. The ANA-positive JIA group showed stronger associations with the HLA-DRB1-DQA1-DQB1 haplotype, HLA-DRB1*11, and HLA-DPB1*02, suggesting a potential connection between genetic factors and ANA production in JIA. Furthermore, logistic regression analysis reaffirmed the effects of HLA alleles, female sex, and lower age at onset on ANA positivity.

Conclusions: This study identified distinct genetic associations between HLA alleles and JIA subtypes, particularly in ANA-positive patients. These findings contribute to a better understanding of the genetic basis of JIA and provide insights into the genetic control of autoantibody production in ANA-positive JIA patients. This may inform future classification and personalized treatment approaches for JIA, ultimately improving patient outcomes and management of this disease.