No association of primary Sjögren's syndrome with Fcγ receptor gene variants.

The genetic background of primary Sjögren's syndrome (pSS) is partly shared with systemic lupus erythematosus (SLE). Immunoglobulin G Fc receptors are important for clearance of immune complexes. Fcγ receptor variants and gene deletion have been found to confer SLE risk. In this study, four Fcγ receptor single-nucleotide polymorphisms (SNPs) and one copy number variation (CNV) were studied. Swedish and Norwegian pSS patients (N=527) and controls (N=528) were genotyped for the Fcγ receptor gene variant FCGR2A H131R (rs1801274) by the Illumina GoldenGate assay. FCGR3A F158V (rs396991) was analysed in 488 patients and 485 controls, FCGR3B rs447536 was analysed in 471 patients and 467 controls, and FCGR3B rs448740 was analysed in 478 cases and 455 controls, using TaqMan SNP genotyping assays. FCGR3B CNV was analysed in 124 patients and 139 controls using a TaqMan copy number assay. None of the SNPs showed any association with pSS. Also, no FCGR3B CNV association was detected. The lack of association of pSS with Fcγ receptor gene variants indicates that defective immune complex clearance may not be as important in pSS pathogenesis as in SLE, and may point to important differences between SLE and pSS.

The point prevalence of clinically relevant primary Sjögren's syndrome in two Norwegian counties.

OBJECTIVE: Primary Sjögren's syndrome (PSS) is a chronic autoimmune inflammatory disease characterized by exocrine gland inflammation producing clinical symptoms such as dryness of the mouth and eyes. The reported prevalence of PSS is variable, probably because of different classification criteria used and selection bias. The aim of this study was to determine the prevalence of PSS in a well-defined Norwegian Caucasian population using the revised American-European Consensus Group (AECG) criteria. METHODS: Three hospitals and three private rheumatology practices provide all of the rheumatology services to the local population in Hordaland and Rogaland counties, which included 852 342 Caucasian inhabitants as of 1 January 2009. Patients on file fulfilling the new revised AECG criteria for PSS were included, and patients with incomplete data were invited to a screening visit. RESULTS: A total of 424 PSS patients were identified. Their mean age was 61.6 ± 13.2 years; 28 (7%) were men and 396 (93%) were women. The point estimate for the proportion of PSS was 0.050% [95% confidence interval (CI) 0.048-0.052]. CONCLUSION: The prevalence of PSS in this Norwegian population of Caucasians is lower than previously reported when less stringent criteria for identifying PSS were used, but is in line with more recent studies using the same criteria and methods as in this study.

Exocrine function in primary Sjögren syndrome: natural course and prognostic factors.

OBJECTIVES: Few studies have addressed the natural course of, or prognostic factors for the salivary and lacrimal function in primary Sjögren syndrome (SS). Except for the early stages, glandular function has been seemingly stable, and SS A antigen (SSA) seropositivity and hypocomplementemia may predict a decline in the van Bijsterveld score. The aim of the present study was to assess the natural course of the exocrine function in a larger cohort based on the American-European consensus criteria for SS, and to address possible predictive factors for a declining exocrine function. METHODS: We performed a retrospective cohort study. A total of 141 patients were investigated with the Schirmer I test and unstimulated whole saliva (UWS). Historical data regarding these tests and focus score were collected from the files of 111 patients. Median time from diagnosis to follow-up investigation was 5.0 years. RESULTS: Median UWS was unchanged during follow-up. Median Schirmer I test improved from 5.0 to 7.0 mm/5 min (p<0.05). Present Schirmer I test was associated with historical high IgG and IgA, positive SSA and SS B antigen (SSB) tests and high focus score, and present UWS with historical low C3/C4. Logistic regression identified high focus scores (odds ratio (OR) = 1.343), and low UWS (OR = 0.692) as factors predicting a 30% or more worsening of the Schirmer I test. High focus scores (OR = 1.488) predicted a 30% or more worsening of the UWS. CONCLUSION: We confirmed previous studies showing a stable or slightly improved exocrine function over time. High focus scores and low UWS were identified as independent predictors of a worsened exocrine function.