No Association between FC γ R3B Copy Number Variation and Susceptibility to Biopsy-Proven Giant Cell Arteritis.

Emma Dunstan,Catherine L Hill,Helen Chan,Alex W Hewitt,Maureen Rischmueller,Sue Lester,Rachel Black

doi:10.1155/2013/514914

Abstract

Objective. To determine the relationship between FCGR3B gene copy number variation (CNV) and biopsy proven giant cell arteritis (GCA). Methods. FCGR3B CNV was determined in 139 Australian biopsy proven GCA patients and 162 population matched controls, using a duplex qPCR assay and RNase P as the reference gene. Copy number was determined using Copy Caller software (v.1.0, Applied Biosystems, USA). CNV genotypes were classified into 3 groups (<2, 2, 3+) for analysis purposes, and analysis was performed using logistic regression. Results. All GCA patients had a positive temporal artery biopsy, and the most common presenting symptoms were visual disturbance and temporal headache. The mean age of patients at biopsy was 74 years (range 51–94) and 88/139 (63%) were female. The frequency of low (<2) FCGR3B copy number was comparable between GCA patients (9/139 = 6.5%) and controls (10/162 = 6.2%), as was the frequency of high (3+) FCGR3B copy number (15/130 (10.8%) in GCA patients versus 13/162 (8.0%) in controls). Overall there was no evidence that FCGR3B CNV frequencies differed between GCA patients and controls (χ 2 = 0.75, df = 2, P = 0.69). Conclusion. FCGR3B CNV is not associated with GCA; however, replicate studies are required.

Highlights

Giant cell arteritis (GCA), known as temporal arteritis, is a systemic inflammatory vasculitis which primarily affects medium to large extracranial arteries of the head and neck and can result in stroke and blindness
The most common Fc gamma receptor 3B (FCGR3B) gene copy number was 2 which was identified in 139/162 (86%) of controls and 114/138 (83%) of GCA patients (Table 2)
There was no evidence that the overall distribution of FCGR3B copy number variation (CNV) genotypes differed significantly between GCA patients and controls nor was there any evidence of a specific difference between GCA patient and controls for low (

Summary

Introduction

Giant cell arteritis (GCA), known as temporal arteritis, is a systemic inflammatory vasculitis which primarily affects medium to large extracranial arteries of the head and neck and can result in stroke and blindness. GCA typically affects people aged over 50 years and incidence rates increase with advancing age, peaking around 80 years of age [1]. GCA is 23 times more likely to affect females and is more commonly diagnosed in Caucasians than in any other ethnic background with the highest incidence observed in populations of Scandinavian descent [2]. Familial aggregation and established associations with HLA-DR4 provide evidence for a genetic component to GCA [3,4,5]. Multiple genetic association studies have been performed on a number of immune response genes. The majority of these studies have been performed on a single GCA cohort from north-western Spain and, to date, have failed to confirm any additional genetic associations

Methods

Results

Conclusion