Association of a polymorphism of the Fcγ-receptor 2A (FCGR2A) gene with chronic periaortitis.

OBJECTIVES: Chronic periaortitis (CP) is an inflammatory disease associated in 20-60% of the cases with IgG4 related disease. Current evidence supports an autoimmune nature for CP. Fc gamma receptors (FcγRs) are involved in several immune system activities and are associated with autoimmunity in general. We explored the influence of genetic variants within this region on susceptibility to CP. METHODS: Genotyping of 4 candidate single nucleotide polymorphisms (SNPs) of the FCGR region was performed in CP patients and controls. RESULTS: One hundred and eighty-three cases and 181 controls were included. An association between the SNP rs1801274 of the FCGR2A and CP was detected (OR 1.6, 95%CI 1.18-2.16;corrected p-value, pcorr=0.0085). After stratification of the population according to clinical characteristics, the association was restricted to cases of idiopathic retroperitoneal fibrosis (OR 1.66, 95%CI 1.21-2.29;pcorr=0.028), without involvement of the thoracic aorta (OR 1.77, 95%CI 1.21-2.57;pcorr=0.043), with deep vein thrombosis at onset (OR 3.96, 95%CI 1.81-8.66;pcorr=0.0021) and with normal IgG4 levels (OR 2.67, 95%CI 1.39-5.12;pcorr=0.031). CONCLUSIONS: In the largest candidate gene approach study performed so far in CP, we demonstrated an association for CP with a gene hallmark of autoimmunity. The association appears restricted to typical cases of CP without increase of IgG4 levels.

Genetic Susceptibility to ANCA-Associated Vasculitis: State of the Art.

ANCA-associated vasculitis (AAV) is a group of disorders that is caused by inflammation affecting small blood vessels. Both arteries and veins are affected. AAV includes microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) renamed from Wegener's granulomatosis, and eosinophilic granulomatosis with polyangiitis (EGPA), renamed from Churg-Strauss syndrome. AAV is primarily due to leukocyte migration and resultant damage. Despite decades of research, the mechanisms behind AAV disease etiology are still not fully understood, although it is clear that genetic and environmental factors are involved. To improve the understanding of the disease, the genetic component has been extensively studied by candidate association studies and two genome-wide association studies. The majority of the identified genetic AAV risk factors are common variants. These have uncovered information that still needs further investigation to clarify its importance. In this review, we summarize and discuss the results of the genetic studies in AAV. We also present the novel approaches to identifying the causal variants in complex susceptibility loci and disease mechanisms. Finally, we discuss the limitations of current methods and the challenges that we still have to face in order to incorporate genomic and epigenomic data into clinical practice.