Identification of a novel non-coding mutation in C1qB in a Dutch child with C1q deficiency associated with recurrent infections.

Introduction: C1q deficiency is a rare genetic disorder that is strongly associated with development of systemic lupus erythematosus (SLE). Several mutations in the coding regions of the C1q genes have been described that result in stop-codons or other genetic abnormalities ultimately leading to C1q deficiency. Here we report on a Dutch boy suffering from recurrent infections with a complete C1q deficiency, without any SLE symptoms.

A genetic variant in osteoprotegerin is associated with progression of joint destruction in rheumatoid arthritis.

Introduction: Progression of joint destruction in rheumatoid arthritis (RA) is partly heritably; 45 to 58% of the variance in joint destruction is estimated to be explained by genetic factors. The binding of RANKL (Receptor Activator for Nuclear Factor κ B Ligand) to RANK results in the activation of TRAF6 (tumor necrosis factor (TNF) receptor associated factor-6), and osteoclast formation ultimately leading to enhanced bone resorption. This bone resorption is inhibited by osteoprotegerin (OPG) which prevents RANKL-RANK interactions.

Genetic studies on components of the Wnt signalling pathway and the severity of joint destruction in rheumatoid arthritis.

Background: Progression of joint destruction in rheumatoid arthritis (RA) is partly heritable; knowledge of genetic factors may increase our understanding of the mechanisms underlying joint destruction. The activity of the Wnt/β-catenin pathway influences osteoblast differentiation. Dickkopf-1 (Dkk-1) and sclerostin (Sost) are negative regulators and lipoprotein receptor-related protein-5 (LRP-5) and Kremen-1 are transmembrane receptors involved in this pathway.

Interaction analysis between HLA-DRB1 shared epitope alleles and MHC class II transactivator CIITA gene with regard to risk of rheumatoid arthritis.

HLA-DRB1 shared epitope (SE) alleles are the strongest genetic determinants for autoantibody positive rheumatoid arthritis (RA). One of the key regulators in expression of HLA class II receptors is MHC class II transactivator (CIITA). A variant of the CIITA gene has been found to associate with inflammatory diseases.

Novel genetic association of the VTCN1 region with rheumatoid arthritis.

Objective: Based upon findings in juvenile idiopathic arthritis, the genetic contribution of the VTCN1 region to rheumatoid arthritis (RA) susceptibility and anticitrullinated protein antibody (ACPA) status was investigated. VTCN1 is known to play a pivotal role in regulation of the immune system and, in soluble form, has previously been associated with higher disease activity.

Methods: Ten VTCN1 polymorphisms were genotyped in 1237 Dutch patients with RA and 1055 healthy controls.

Complement activation by (auto-) antibodies.

The complement system is a key part of the innate immune system and plays an important role in the clearance of pathogens and apoptotic cells upon its activation. It is well known that both IgG and IgM can activate complement via the classical pathway by binding of C1q to the Fc regions of these immunoglobulins. Recent advances have shown that also IgA is capable of activating the complement system.

Rheumatoid arthritis: Are ACPA-positive and ACPA-negative RA the same disease?

Seemingly contrasting genetic backgrounds in anti-citrullinated-protein antibody (ACPA)-positive and ACPA-negative rheumatoid arthritis (RA) support the notion that these are in fact two distinct disease subsets, with different underlying pathogenesis, that might need tailored treatment strategies.

Variants of gene for microsomal prostaglandin E2 synthase show association with disease and severe inflammation in rheumatoid arthritis.

Microsomal PGE synthase 1 (mPGES-1) is the terminal enzyme in the induced state of prostaglandin E(2) (PGE(2)) synthesis and constitutes a therapeutic target for rheumatoid arthritis (RA) treatment. We examined the role of the prostaglandin E synthase (PTGES) gene polymorphism in susceptibility to and severity of RA and related variations in the gene to its function. The PTGES gene polymorphism was analyzed in 3081 RA patients and 1900 controls from two study populations: Swedish Epidemiological Investigation of Rheumatoid Arthritis (EIRA) and the Leiden Early Arthritis Clinic (Leiden EAC).

PADI4 polymorphism predisposes male smokers to rheumatoid arthritis.

Objective: To elucidate the differential role of peptidyl arginine deiminase 4 (PADI4) polymorphism in rheumatoid arthritis (RA) between Asian and European populations, possible gene-environmental interactions among the PADI4 polymorphism, sex and smoking status were analysed.

Methods: Three independent sets of case-control samples were genotyped for single-nucleotide polymorphisms in PADI4; Japanese samples (first set, 1019 RA patients, 907 controls; second set, 999 RA patients, 1128 controls) using TaqMan assays and Dutch samples (635 RA patients, 391 controls) using Sequenom MassARRAY platform. The association of PADI4 with RA susceptibility was evaluated by smoking status and sex in contingency tables and logistic regression models.

Confirmation of STAT4, IL2/IL21, and CTLA4 polymorphisms in rheumatoid arthritis.

Objective: Recent advances have led to novel identification of genetic polymorphisms that are associated with susceptibility to rheumatoid arthritis (RA). Currently, 5 loci (HLA, PTPN22, TRAF1/C5, TNFAIP3, and STAT4) have been consistently reported, whereas others have been observed less systematically. The aim of the present study was to independently replicate 3 recently described RA susceptibility loci, STAT4, IL2/IL21, and CTLA4, in a large Dutch case-control cohort, and to perform a meta-analysis of all published studies to date and investigate the relevance of the findings in clinically well-defined subgroups of RA patients with or without autoantibodies.