Association of copy number variation in Fc gamma receptor IIIb gene with risk of Graves' ophthalmopathy

Abstract

The functional polymorphism that explains the established association of Fc gamma receptor IIIb (FCGR3B) with Graves' disease (GD) and Graves' ophthalmopathy (GO) remains unidentified, but copy number variation (CNV) might be relevant. The aim of this study was to determine whether CNV for FCGR3B is associated with GD and GO. Genotype analysis involved 624 GD patients, including 397 without GO (GDnonGO) and 227 with GO (GDGO), and 227 healthy controls. The relative copy number (CN) ofFCGR3B was determined using a relative real-time quantitative polymerase chain reaction. Our findings indicated the distribution of the relative CN of FCGR3B significantly differed between the GDGO patients and the healthy controls (p = 0.02) but not between the total GD patients and the healthy control groups (p = 0.06). Individuals with less than 2 CN or more than 2 CN of FCGR3B were at significantly decreased risk of developing GDGO. In addition, GD patients with less than 2 copies of FCGR3B were at reduced risk for developing nodular hyperplasia and vitiligo, but at increased risk for myxedema. Our results suggest that CNV of FCGR3B is associated with the development or progression of GD in Taiwan Chinese population.