Risk of relapse of ANCA-associated vasculitis among patients homozygous for the proteinase 3 gene Val119Ile polymorphism

Abstract

BackgroundThe frequency of proteinase 3 gene (PRTN3) polymorphisms in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is not fully characterised. We hypothesise that the presence of a PRTN3 gene polymorphism (single nucleotide polymorphism (SNP) rs351111) is relevant for clinical outcomes.MethodsDNA variant calling for SNP rs351111 (chr.19:844020, c.355G>A) in PRTN3 gene assessed the allelic frequency in patients with PR3-AAV included in the Rituximab in ANCA-Associated Vasculitis trial. This was followed by RNA-seq variant calling to characterise the mRNA expression. We compared clinical outcomes between patients homozygous for PRTN3-Ile119or PRTN3-Val119.ResultsWhole blood samples for DNA calling were available in 188 patients. 75 patients with PR3-AAV had the allelic variant: 62 heterozygous PRTN3-Val119Ile and 13 homozygous for PRTN3-Ile119. RNA-seq was available for 89 patients and mRNA corresponding to the allelic variant was found in 32 patients with PR3-AAV: 25 heterozygous PRTN3-Val119Ile and 7 homozygous for PRTN3-Ile119. The agreement between the DNA calling results and mRNA expression of the 86 patients analysed by both methods was 100%. We compared the clinical outcomes of 64 patients with PR3-AAV: 51 homozygous for PRTN3-Val119and 13 homozygous for PRTN3-Ile119. The frequency of severe flares at 18 months in homozygous PRTN3-Ile119was significantly higher when compared with homozygous PRTN3-Val119(46.2% vs 19.6%, p=0.048). Multivariate analysis identified homozygous PR3-Ile119as main predictor of severe relapse (HR 4.67, 95% CI 1.16 to 18.86, p=0.030).ConclusionIn patients with PR3-AAV, homozygosity for PRTN3-Val119Ile polymorphism appears associated with higher frequency of severe relapse. Further studies are necessary to better understand the association of this observation with the risk of severe relapse.

Evaluating Single-Nucleotide Polymorphisms in Inflammasome Proteins and Serum Levels of IL-18 and IL-1β in Kidney Interstitial Damage in Anti-Neutrophilic Cytoplasmic Antibody-Associated Vasculitis

“…Several authors studied the association of certain SNPs in the human leukocyte antigen (HLA) regions and found differences in frequency according to ANCA specificity (myeloperoxidase (MPO) or proteinase-3 (PR3)) [ 14 , 15 ]. Casal Moura et al found an association of rs351111, located in the PR3 gene, with a higher frequency of severe relapses in a cohort of 188 patients [ 16 ]. Certain TLR9 , protein tyrosine phosphatase non-receptor type 22 ( PTPN22 ), and IL2 receptor-A SNPs involved in lymphocyte activation pathways have also been associated with higher disease susceptibility, suggesting their pathophysiologic role [ 17 , 18 , 19 ].…”