Systemic sclerosis (SSc) is a clinically heterogeneous autoimmune disease characterized by mutually exclusive autoantibodies directed against distinct nuclear antigens. We examinedHLAassociations in SSc and its autoantibody subsets in a large, newly recruited African American (AA) cohort and among European Americans (EA). In the AA population, the African ancestry-predominantHLA-DRB1*08:04andHLA-DRB1*11:02alleles were associated with overall SSc risk, and theHLA-DRB1*08:04allele was strongly associated with the severe antifibrillarin (AFA) antibody subset of SSc (odds ratio = 7.4). These African ancestry-predominant alleles may help explain the increased frequency and severity of SSc among the AA population. In the EA population, theHLA-DPB1*13:01andHLA-DRB1*07:01alleles were more strongly associated with antitopoisomerase (ATA) and anticentromere antibody-positive subsets of SSc, respectively, than with overall SSc risk, emphasizing the importance ofHLAin defining autoantibody subtypes. The association of theHLA-DPB1*13:01allele with the ATA+subset of SSc in both AA and EA patients demonstrated a transancestry effect. A direct correlation between SSc prevalence andHLA-DPB1*13:01allele frequency in multiple populations was observed (r= 0.98,P= 3 × 10−6). Conditional analysis in the autoantibody subsets of SSc revealed several associated amino acid residues, mostly in the peptide-binding groove of the class II HLA molecules. Using HLA α/β allelic heterodimers, we bioinformatically predicted immunodominant peptides of topoisomerase 1, fibrillarin, and centromere protein A and discovered that they are homologous to viral protein sequences from the Mimiviridae and Phycodnaviridae families. Taken together, these data suggest a possible link betweenHLAalleles, autoantibodies, and environmental triggers in the pathogenesis of SSc.

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Despite being able to describe a number of roles for PAs, these were highly variable. The lack of mandatory training and a clearly articulated role for PAs in New Zealand meant that in some cases PAs might be seen as little more than general retail assistants--a view not in line with their actual roles and practices. Attention to these issues may well help to resolve this, as will public education about the PA's role.

In the largest genetic study in AA patients with SSc to date, our findings corroborate the role of functional variants that aggregate in a fibrotic pathway and increase SSc susceptibility.