The Limitation of HLA Diversity as a Risk Factor for Pediatric-Onset Autoimmune Rheumatic Disease

Area of Science:

• Immunogenetics
• Rheumatology
• Autoimmunity

Background:

• Specific Human Leukocyte Antigen (HLA) allele homozygosity is linked to increased autoimmunity and severe disease phenotypes.
• The impact of overall reduced HLA diversity across multiple loci on autoimmunity risk remains largely undetermined.

Purpose of the Study:

• To investigate the association between Limitation of HLA Diversity (LoHLAD) across multiple loci and the risk of pediatric-onset autoimmune rheumatic diseases.
• To determine if LoHLAD acts as an allele-independent risk factor for autoimmunity.

Main Methods:

• A case-control study involving 279 cases with pediatric-onset autoimmune rheumatic diseases and 134 matched controls.
• Analysis of LoHLAD across five HLA loci (A, B, DQB1, DRB1, DRB3/4/5).
• LoHLAD defined by homozygosity at any locus or specific allele patterns at the HLA-DRB3/4/5 locus.

Main Results:

• The frequency of LoHLAD was significantly higher in cases (65.95%) compared to controls (30.60%), indicating a 4.39-fold increased risk (OR 4.39).
• Elevated LoHLAD frequencies were observed in both class I (OR 2.06) and class II (OR 4.74) HLA loci among cases.
• Significant associations were found at HLA-B (OR 8.63), HLA-DQB1 (OR 3.34), and HLA-DRB3/4/5 (OR 4.64) loci.

Conclusions:

• Limitation of HLA Diversity (LoHLAD) is a significant, allele-independent risk factor for pediatric-onset autoimmune rheumatic diseases.
• This finding highlights the importance of considering overall HLA diversity, not just specific alleles, in autoimmunity risk assessment.