FCGR3A and Guillain-Barre syndrome: The data demonstrate that; (1) there are no differences in frequencies of SNPs and CNVs between all patients with GBS and controls, (2) duplications in FCGR3A are more frequent in GBS patients with an antecedent C. jejuni infection compared to controls, (3) more copies of FCGR3A are associated with severe disease and (4) genetic variation at the FCGR2/3 locus is not associated with ΔIgG serum concentrations.